From idea to a tool
SL

Vibe coding for non-programmers

If you can describe what you need, you can build a working tool with AI: a calculator, an automation, a data overview or a small web app. You do not need to know how to program.

This guide covers how to start, what it costs, what not to leave to the model, and how to publish the result.

Seven examples to start with

Each example replaces something you now do by hand: scrolling listings, copying into spreadsheets, switching between tabs. Under each description is a sentence you can start with.

  • Listing finder

    Every morning you get a list of new listings compared against the market price; an alert only when a deal is actually good.

    "Find me new e-MTBs under €1,600, and tell me which ones are actually a good buy and why."

    Details →
  • Collecting data from the web

    Several public sources become one clean table, chart or overview — no copying between tabs by hand.

    "Every week, read these three pages and make me one table of prices by supplier."

    Details →
  • Personal recommendations

    Films, books or music suggested from your own favourites, not general popularity.

    "Here is a list of films I liked. Suggest five similar ones I have not seen."

  • Travel plan

    Sights, cheap connections and real distances between stops, fitted to your actual itinerary.

    "Here is my Lisbon itinerary. Add cheap transport between stops and flag it if opening hours do not line up."

  • Web portfolio and CV

    From old references, images and one visual reference comes a web page and a one-page A4 CV.

    "I have an old CV and project photos in this folder. Build me a simple portfolio that works on a phone."

    Details →
  • Surf alert

    Waves, wind and tide get checked for you; a message arrives only when conditions fall within your limits.

    "Every evening check tomorrow's forecast, and only message me if the swell is over a metre with offshore wind."

  • Meal plan and shopping list

    From your preferences, what you already have and your budget comes a menu and one merged shopping list.

    "Make me a two-week menu from these recipes and one shopping list, ordered by aisle."

If you have ten minutes
  1. Pick one thing you currently do by hand, or open several apps to do.
  2. Tell the AI what you have, what you want, and show an example.
  3. Ask for a first working version, try it, and fix concrete mistakes.

That is enough for a first project. Git, models, context and deployment come later.

1What vibe coding is

Andrej Karpathy (OpenAI co-founder, former head of AI at Tesla) defined the term on 6 February 2025 in a single post:

“There's a new kind of coding I call “vibe coding”, where you fully give in to the vibes, embrace exponentials, and forget that the code even exists. […] I “Accept All” always, I don't read the diffs anymore. When I get error messages I just copy paste them in with no comment, usually that fixes it. […] I'm building a project or webapp, but it's not really coding — I just see stuff, say stuff, run stuff, and copy paste stuff, and it mostly works.”

Simon Willison (co-creator of Django and a long-running blogger on working with LLMs) drew the line between that and real work:

“If an LLM wrote the code for you, and you then reviewed it, tested it thoroughly and made sure you could explain how it works to someone else — that's not vibe coding, it's software development.”

In October 2025 he coined a name for the disciplined version: vibe engineering — “seasoned professionals accelerate their work with LLMs while staying proudly and confidently accountable for the software they produce”. This guide teaches that: the agent writes the code, you stay accountable for the result.

How an agent works

A coding agent is a program that reads your files, edits them, runs commands, and reads its own errors — in a loop, until the task is done:

request inspect & plan edit run & test result error → fix
The agent sees the result of its own work and fixes errors itself. You review the final result.

This loop is what makes the method useful: the model runs the code and sees the result instead of guessing.

2What you can build and what you cannot

The method is reliable where you can check the result yourself. Where you cannot, you need an additional review.

Usually works well

  • Internal tools — for you or your team
  • Calculators and converters
  • Data processing and analysis
  • Scripts for repetitive chores
  • Dashboards over your own data
  • Prototypes and landing pages
  • Firmware and electronics prototypes*
  • Format conversions and reports

Do not trust without review

  • Products for outside users
  • User accounts and passwords
  • Personal data (GDPR)
  • Database access rights
  • Payments and financial data
  • Anything reachable from the internet
  • Architecture of a larger system
Working is not the same as safe

An LLM or a coding agent can produce a complete software product. What you must not do is assume it is secure, correct and production-ready merely because it runs, or because the agent finished. The model routinely overlooks security gaps — password handling, personal data, database permissions — and proposes architecture that is hard to maintain later.

For authentication, payments, personal and health data, and anything publicly exposed, require testing, code review and an expert check of the key risks before it goes into use.

The quickest gains come from automating your own tasks, for yourself or inside a company, where you know the users and the scope of the risk.

* For firmware and electronics the method is very useful for prototypes, but do not assume correctness in safety-critical, high-voltage, medical or other systems where a fault causes physical harm.

An example that shows the difference

LDFcalc is a recipe calculator for composite filament: from the chosen matrix (PLA, PA6, PC), the fibre type and length, and the machine batch capacity, it computes the mass and volume of every component for a target carbon- or glass-fibre volume fraction. It was built with a single prompt. It saves roughly ten manual calculations per project.

Why it works: the task has a clearly defined input, a known formula, and a verifiable output. No user accounts, no database, no personal data. You can check the result with a pencil. This is the kind of task where the method works best.

The counter-example: the same page with customer logins, saved quotes, and payment would need a security review the model does not reliably perform. The first version would probably work, so the flaws would stay hidden.

“Internal” does not automatically mean “safe”

An internal tool removes some of the risk, not all of it. You have to know where the data goes. Distinguish three cases: a local model (data stays on the machine), the provider's API or app (content goes to the cloud), and a cloud agent (your code and files execute at the provider).

For sensitive data, check your organisation's rules and the actual data flow, not just whether you call the tool “internal”. See chapter 16.

Where the limit is in practice

The Stack Overflow 2025 survey names the same problem most often — 66% of developers cite solutions that are “almost right, but not quite”. That is why verification is part of the method, not an add-on. Who verifies determines the scope: for an internal tool it is enough that you check the output; for a public product you need someone who can read the code.

3What people build

Analyses of Reddit posts (r/vibecoding, r/ClaudeAI, r/ChatGPTCoding) show most of the activity around internal tools, prototypes, landing pages, and personal projects — not large products. The most-mentioned tools are Claude Code and Codex; a common route is a fast prototype in a browser tool (Lovable, Bolt), then a move to Claude Code or Codex for serious work (mention analysis).

Karpathy builds a web app

The author of the term used the method to build a real app, MenuGen: “You take a picture of a menu and it generates images for all the menu items.” He is not a web developer; Cursor and Claude wrote the code. His write-up is more useful than the app:

“I didn't even spend all that much work in the code editor itself. I spent most of it in the browser, moving between tabs and settings and configuring.”

Writing code is no longer the bottleneck. The bottleneck is glue work — auth, payments, keys, domains, settings. The model cannot do that for you, because it needs your account and your decision.

Simon Willison's 230+ tools

Willison publicly maintains tools.simonwillison.net: more than 230 small web tools, nearly all built with an LLM. The most instructive part is the colophon: each tool lists its commit messages, and many link to the full transcript of the conversation with the model. The code is open on GitHub. If you want to see how something was actually made, this is the best free material available.

The official use-case catalog

Anthropic’s catalog of sensible use cases for non-coding tasks lists tasks where an LLM helps. It is organised by role (engineering, data, research, marketing, finance, HR, legal). Examples such as “Build a daily briefing across your tools”, “Analyze patterns in user feedback”, and “Forecast & scenario modeling” come with concrete steps.

4The author's projects

I built these projects in my spare time as a mechanical engineer, with no programming background. All links work.

Tools You Can Use Right Away

Physical and Interactive Projects

More Ambitious Experiments

What they have in common

In none of them was programming the goal in itself — the code was a tool for a concrete problem. They are instruments, games, a workshop, tourism, and safety at sea, and all of them are internal tools where the author is both the user and the tester. None has user accounts, payments, or personal data. That is exactly the territory where the method works best (see chapter 2).

5At work and for your career

The chapter starts with a portfolio and CV because they make a good first project: the result is immediately visible and useful. Everyday work tasks and examples by profession follow.

Portfolio and CV

You give the agent your references, a few images and an example page you like. After a few rounds of corrections you have a web portfolio and a PDF CV from the same source. You see the result in the browser immediately, a correction is one sentence, and the finished thing is a link you can send to an employer or a client.

Why it suits a first project:

  • The result is visible and verifiable. You open the page and know within a second whether it is good. You can check a result like that yourself (chapter 2).
  • You already have the content. An old CV, LinkedIn, project descriptions, photos of your work. You invent nothing — the agent rearranges and typesets.
  • You can paste a visual reference. A screenshot of a page you like, or a link to it. “Make it more like this” works far better than “make it prettier”.
  • One source, two products. The same data gives you a web page with a public link, and printing that page to PDF gives you a one-page CV.
  • Maintenance is one sentence. Six months later: “add this project and update the date.” No Word, no re-breaking the layout.
The portfolio and CV prompt — ready to copy

Put the old CV, the images and the descriptions in one folder first, start the agent in it, and paste the text below.

I have an old CV, project descriptions and a few photos in this
folder. Build me a simple personal portfolio from this that works
well on a phone and that I can also print as a one-page A4 CV.

Do not invent any data - use only what is in the folder. First review
the material and pick the 3 to 6 best projects, then show me the
proposed structure before you start writing code.

For the look, use the attached reference (a link or a screenshot) -
take the proportions and the calm, not the content. One typeface,
one accent colour, light and dark theme.

After every version, take a screenshot at 390 px and 1440 px wide and
show it to me. At the end, add @media print so the page prints on one
A4 sheet with no navigation.

After two or three rounds of corrections (“the heading is too big”, “put the projects in a grid”, “the print breaks onto a second page”) it is done. Deploying is covered in chapter 15 and is free.

Whatever the CV says has to be true

An agent will polish prose to the point where the content drifts from the truth. Read and confirm every claim, number and date yourself before you publish. And do not publish your home address, date of birth or scanned documents — a public page is public (chapter 16).

Seven typical tasks

  • Building other people’s software. You find an open-source tool that almost does what you need. The agent downloads it, compiles it (turns the source code into a program the computer can actually run), adds your patch, and writes down what it changed. This used to mean a week of reading someone else’s build instructions.
  • Programs for small devices. Firmware is a program that runs directly on a device with no operating system, the same way the program in a washing machine or a thermostat does. An ESP32 is a cheap microcontroller, a computer the size of a postage stamp costing about €5, with Wi-Fi built in. Example task: “Have an ESP32 read a temperature sensor every 10 s and save the readings to CSV.” The agent writes the program and tells you which sensor wire goes to which pin (the pinout).
  • Literature review. Selecting papers, extracts of methods and results, comparison tables with citations. Open and check the citations, because the model can get them wrong.
  • Measurements and reports. A script reads the raw exports from an instrument, removes errors and duplicate rows, plots charts, and drafts a commentary. You approve the conclusions.
  • Scripts for small chores. Renaming 400 files by pattern, merging PDFs, Excel formulas and macros, converting between formats. Chores that were never worth looking for a tool for.
  • Single-purpose apps. A tally counter with big buttons for counting events during a measurement, a sample-entry form, a protocol timer. Each takes about half an hour.
  • Metrics. A script reads the weekly export and plots the key indicators (KPIs) on one page that management can read too.

Find your profession

The professions below have little to do with computing at first glance. The same rule applies to each: take a task you currently do by hand that has a verifiable result. Hover over a tile or tap it to reveal the description.

Health, law, finance: the tool does not decide

In regulated professions, build administrative and research tooling only. Health and other sensitive personal data belong in an approved environment: the tool should run locally, with no cloud and no identifying data in the files. No such tool may take part in diagnosis, dosing, legal advice or a credit decision. See chapter 16.

Everyday life and hobbies

The method does not distinguish between work and free time — the seven ideas above apply just as well to hobbies. Here are a few life situations they didn't cover.

  • Running and cycling

    Turning GPX files into a weekly summary: distance, elevation, pace by segment, compared with the same route last month.

  • Home and bills

    An energy-use tracker from monthly readings; service reminders; a payback calculator for a heat pump; a contractor-quote comparator.

  • Parent

    A feed and sleep log with big buttons, no login; a clothing-size tracker; appointment reminders; a monthly album from a photo folder.

  • Hobbies and workshop

    A schedule for a tournament or club; a materials-stock tracker for the workshop; a timer and log for a personal project built in stages.

What code should do and what the model should do

Deterministic work stays plain code — collection, filtering, computation. That way you can check and repeat the result at any time.

Use the model for unstructured text — summaries, borderline classification, explanations, extraction from free text. And verify every number that matters before it enters a report.

Tools the agent already knows: DuckDB (analytical SQL over local files, no server), Polars or pandas for tables, Jupyter for exploration, Streamlit for a colleague-facing interface.

6Getting started: three decisions

Three steps to a first working result. The following chapters explain them in more detail.

  1. Choose a provider

    Test ChatGPT, Claude, and Gemini on three or four of your own tasks: one writing task, one data task, one document or screenshot, and one small coding task. Use the free tiers.

    Pick the one whose answers you most often keep without major repair. Do not decide by leaderboards — see Choosing a Model.

  2. Choose a way of working

    For questions and short transformations, use chat. For a task across several files, Work/Cowork. For a project that must be edited and run, a coding agent. For recurring chores, a schedule.

    Detail in Ways of Working and Tools.

  3. Start working

    Write clearly what you want and how. A reliable result also needs a check. A good first request answers four questions:

    • What it should do — the function, in one sentence.
    • What goes in and what comes out — inputs, outputs, units, formats.
    • How it should look and behave — no login, works on a phone, works offline.
    • What it must not do — no database, no external libraries, no user accounts.

    An example of such a request — this is how LDFcalc was made:

    I work out recipes for composite filament and want to stop doing the
    maths by hand every time. Build me one simple web page where I enter
    the matrix (PLA, PA6 or PC), the fibre type (carbon or glass), its
    length and the machine batch capacity; the target fibre fraction
    should recalculate the mass and volume of every component live, with
    no "calculate" button.
    
    Make it one page, no login and no database, and it should work on a
    phone and offline. Keep the material densities visible and let me
    edit them if I need to.

    Then verify the result. For a calculator, work one case out by hand. For data processing, compare a few rows against a known answer. If you cannot verify the output, the task is not specified correctly yet.

How to choose a first project

Take a task you currently do by hand that has a verifiable result: a calculation, a conversion, a report, a list. Do not start with user accounts, payments, or a “platform”. Your first project should be something you will use this week.

Free official courses, if you prefer guided teaching: Claude Academy (Claude 101 → Claude Code in Action), OpenAI Academy, Google AI Essentials, GitHub Skills.

7Ways of working and tools

You can use the same model in four ways. Product names change, the ways stay. The way you work also affects the result: which tools the model has and how much of your project it can see.

ModeWhat It DoesUse It For
Chat Answers, writes, analyzes uploaded files. You coordinate. Questions, drafts, short scripts, explaining unfamiliar code.
Knowledge-work agent
(ChatGPT Work, Claude Cowork)
Completes a bounded knowledge-work task across selected files and connected tools. Reports, document review, tidying folders, repetitive office work.
Coding agent
(Claude Code, Codex)
Runs locally on your machine. Reads and edits files, runs commands, tests, and builds. Anything that is a project: apps, scripts, firmware, data processing.
Scheduled or triggered task Fires on its own at an agreed time and sends you the result. Daily reviews, watching listings and prices, morning briefings.

What a coding agent can do

You use Claude Code and Codex in a terminal, a code editor or a desktop app. Both also have a web mode where the code runs at the provider. When the agent works in a folder on your machine:

  • It reads your files. It sees what you have instead of guessing from a description.
  • It runs commands (builds, tests, scripts) and reads their output.
  • It fixes its own errors until the test passes.
  • It works with Git: it sees history, saves and compares versions.
  • The project can be larger than the context, because the agent reads files as needed. You can also put manuals as PDFs, old scripts and templates in the folder; the agent finds what it needs.
  • You see every change as a diff and can reject or revert it, instead of copying code out of a chat.
  • It is included in the subscription (chapter 9).
Local execution is not a local model

The agent runs on your machine, but the files it reads, the command output and your messages are sent to the model provider. The data does not stay only on your disk.

Check the retention and data-usage settings (Claude Code: data usage). If the data must not leave your machine, you need a local model (chapter 16).

Anthropic recommends giving the agent a way to check its own work: a test, a build or a screenshot to compare. “It's the difference between a session you watch and one you walk away from.” (Claude Code best practices)

Skills — saved procedures

Instructions you use again and again can be saved as a skill: a folder with a SKILL.md file where the procedure is written once. The agent uses it when relevant, or you invoke it directly with /skill-name.

Unlike CLAUDE.md, a skill loads only when used, so long instructions take no context until you need them (documentation). Examples: a release procedure, a review checklist, style rules, a report format.

Listing finder

Prompt for the listing finder

The prompt below is ready to copy. Replace only the contents of the square brackets. It works the same for Bolha, Avto.net, property portals and second-hand equipment listings.

Every day at 8.00 check bolha.com for: [WHAT YOU WANT].

HARD FILTERS (no exceptions)
- price: [FROM]-[TO] EUR
- location: within [X] km of [PLACE], or shipped
- age / year / condition: [...]
- exclude listings containing: faulty, for parts, damaged,
  replica, not working, [YOUR OWN WORDS]

WHAT COUNTS AS A GOOD DEAL
- compare against other active listings for the same model
- rate the price as: below market / market / above market, and by how many %
- account for condition, age, included accessories and distance
- if the price is far below market, flag that explicitly as suspicious

THE REPORT
- only listings that are NEW since the last check, never repeat ones I saw
- at most 5, ranked by value for money
- for each: title, price, location, how old the listing is, link
- one sentence: why it stands out
- one sentence: what to watch out for (missing photos, vague
  description, a common fault on this model, price too low)
- at the end: how today compares with last week

RULES
- if there is nothing new worth seeing, just write "nothing new"
- never invent a price or a detail that is not in the listing
- always include the original link

Clear limits keep the number of matches down, and asking only for new listings stops repeats. The most important line is the ban on inventing details: without it the model tends to fill gaps. For the first few days compare the report with the original listings and adjust the criteria.

Scheduled tasks — two real prompts2 examples

A scheduled task needs no code. You describe it in plain words, even very briefly:

every day at 8.00 search bolha for e-mtb and give me a curated list
of current best offers, what makes them stand out and what I should
be careful about and how they compare to other current and past offers

The pattern is useful for publicly reachable sources that the chosen tool may and can open — Bolha, Avto.net, property portals, tenders, flight prices. Sites behind a login or CAPTCHA, or that forbid automated access, will need a different source or an official integration. The second real prompt, which produced Ljubljana Bulletin:

create a retro-looking ljubljana bulletin for tourist in style of
new york times that scrapes events from xx.dsd, yy.com, ztz.com websites,
curates them and publishes them daily

Anthropic gives developers the same advice: “find the simplest solution possible, and only increasing complexity when needed” (Building effective agents). Build an application only when a scheduled task is no longer enough.

8Choosing a model

Public benchmarks say little about your work. Take three or four tasks you actually do and give them to several models. Keep the one whose answers you most often use without edits.

ChatGPT, Claude and Gemini

The table summarises published comparisons and user experience, not a test of my own. Use it as a starting point.

ProviderGood atWeaker atPick it if
ChatGPT The most features in one app: images, voice, connections to other services, Codex. Consistency on long agent sessions; the product changes often. You want one subscription for everything and often work with images or speech.
Claude Code and long documents; Claude Code as a coding agent. No image generation; long sessions use up limits quickly. You mostly build projects or work with text.
Gemini Large PDFs, video and images; built into Gmail, Drive and Docs; a large free tier. Quality varies between modes; interfaces need more direction. You already work in Gmail, Drive and Docs.

Which model tier

Every provider has models in three tiers. The names change; the price gap between tiers is often fivefold or more.

  • Small model (Haiku, mini): summaries, sorting, simple conversions and short, well-scoped coding tasks. Not the first choice for hard debugging.
  • Default model (Sonnet, main GPT, Gemini Pro): where most users get their work done. Start here.
  • Most capable model (Fable/Opus, Deep Think): large rewrites, hard reasoning, tasks where the default fails repeatedly. Slower, and it uses up limits faster; your plan says by how much.
When to switch to a more expensive model

When the default fails on a clearly specified task. Switch back once the hard part is done. Cost per token is not cost per correct result: a cheap model that needs five attempts costs more than an expensive one that succeeds in one (Claude Code cost analysis).

Market and pricesSeptember 2026
Prices are approximate

Monthly web-subscription prices for the EU excluding VAT, checked September 2026. These are not API prices and can differ from App Store or Google Play prices. SuperGrok and Mistral Vibe are listed in dollars because they publish no euro price.

Names, plans and limits change faster than this page. The provider's official price list applies: Anthropic, OpenAI, Google.

ProductGood AtWeaknessesPrice
ChatGPT / GPT‑5.6 General work, code, documents, images, tools, voice. Fast product churn; limits under heavy agent use. Plus ~€23–25/mo
Pro ~€200/mo
Claude / Sonnet 5 Codebases, prose, long documents, Claude Code. Verbose; long sessions use up limits fast. Pro ~€18/mo
Max 5× ~€100/mo
Claude / Fable 5.1 Large migrations, hardest tasks, long unattended work. Slow; uses up limits faster than the default. Max 20× ~€200/mo
Gemini / 3.1 Pro Large PDFs, media, Gmail/Drive/Docs, long context. Quality varies by mode. AI Pro ~€22/mo
Gemini / Deep Think Hardest reasoning; explores several approaches at once. Slow; tied to an expensive plan. AI Ultra from ~€100/mo
Grok 4.5 Code, live web and X, images and video in one product. Uneven reliability; fewer tools around it. SuperGrok $30/mo
Mistral Vibe EU hosting, fast general work, chat and agent combined. Less consistent on the hardest reasoning. Pro $14.99/mo
DeepSeek V4 Cheap reasoning and code; open weights. Data is processed outside the EU; not for confidential work. Free; API metered
Qwen 3.7 Multilingual work, open models, the Qwen Code agent. Thinner English documentation. Free / local
M365 Copilot Excel, Word, Outlook, and organizational data. The advantage is the Office integration, not the model. from ~€20/user/mo

Other useful tools: Perplexity (cited search; open and check the citations), NotebookLM (answers strictly from uploaded sources), Elicit and Consensus (academic literature), Lovable and Bolt (browser prototypes, nothing to install).

9Subscription vs API

Beginners often pay API rates for work their subscription already covers. The difference is in what you pay for.

SubscriptionRecommended to startAPI
What you pay forA person using the provider's app.Every call from your code, metered by tokens.
The billA fixed monthly amount. You know it in advance.Variable; grows with usage. A runaway loop gets expensive.
LimitsUsage limits within a period.Pay as you go; beyond your budget there are also rate limits, quotas and per-model limits.
What you need to startJust an account. No setup.A key, a payment method, and code that calls it.
Use it forWork inside the provider's app and a coding agent.The model as part of your own software: your own interfaces, batch processing, evaluation, version pinning, integrations.
How much a subscription saves

In one published heavy-use account, a $200/month subscription replaced usage that would have cost roughly $1,588 at list API rates , roughly an eightfold difference (Product Compass; CloudZero reports similar figures).

That is not a rule for everyone: for occasional use the API can be cheaper. For daily work with an agent the subscription is almost always cheaper.

To start, I recommend a subscription, for four reasons:

  • The price is known in advance. You pay a fixed monthly amount. On the API every attempt costs money, so you count calls while learning.
  • No surprise bills. At the start you try and revert the most. On a subscription only the plan limits hold you back; on the API this is the most expensive phase.
  • Nothing to set up. You need no API keys, so you cannot accidentally publish one on GitHub.
  • The coding agents are included. Claude Code and Codex use the most tokens, so that is where the price gap is widest.

You need the API when the model becomes part of your own software: your own app, automatic processing of larger amounts of data, or use of one exact model version.

A subscription does not cover the API. ChatGPT Plus and the OpenAI API are separate accounts with separate billing; the same holds for Claude.

The coding agents, however, are included in the subscription:

  • Codex is included in ChatGPT plans, with limits that differ between plans. Access on Free and Go is currently time-limited; check when you sign up (OpenAI: Using Codex with your ChatGPT plan).
  • Claude Code is included in the relevant Claude plans (Pro, Max and business plans); check the current limits with Anthropic.

10The context window

Most good practices for working with an agent follow from one constraint:

“Most best practices are based on one constraint: Claude's context window fills up fast, and performance degrades as it fills.”

The context window is everything the model considers at once for the current task: your messages, its replies, the contents of files it read, and command output. It is measured in tokens — chunks of text, roughly three quarters of a word.

During a longer session the amount of history grows until the system compacts, summarises or truncates it. A single debugging session can use tens of thousands of tokens. Compaction loses detail, so the model later forgets early instructions. So keep unrelated tasks apart and write important rules into project files and tests.

How to manage context6 rules
  • Start a new session when a task is done. The model carries the whole long conversation into every following answer.
  • Collect your remarks and send them at once. Ten messages with one remark each use more tokens than one message with ten, because each re-sends the whole history.
  • Put standing rules in AGENTS.md or CLAUDE.md instead of repeating them. Save longer procedures as a skill, which loads only when used.
  • Send excerpts. The diff, the filename and the part of the log with the error, not the full output.
  • Clear between unrelated tasks. In Claude Code that is /clear; elsewhere, a new conversation.
  • Use subagents for investigation. A subagent reads many files in its own context and returns only a summary, so your context stays free.

Subscription plans meter usage in tokens, so saving context also saves your limits. A cluttered context is a common reason an agent starts doing worse mid-session.

11Workflow

Ten steps from idea to a published tool. The first three are preparation and have the most influence on the result.

Ten steps10 steps
  1. One-page brief

    Write down who will use the tool, what problem it solves, what goes in and out, the constraints and when the work is done. Add what the tool will not do. Template: PROJECT-BRIEF.md.

  2. Sketch the flow

    Sketch screens and data flow in Excalidraw. Write the structure in Mermaid so it stays in the project next to the code.

  3. Project instructions

    Write a short AGENTS.md or CLAUDE.md: stack, commands, key files, forbidden changes. Include only what the model cannot tell from the code.

  4. Plan before editing

    Anthropic recommends four phases: explore, plan, implement, commit. The agent first only reads and proposes a plan; it writes code after you approve. One exception: “If you could describe the diff in one sentence, skip the plan.”

  5. One complete example

    First get one full example working from input to output, with real data. A real file has odd dates and decimal commas; a test file does not.

  6. Run and verify

    The agent runs the build and tests; you check the output: a screenshot for the interface, a known answer for data, one hand calculation for a calculator.

  7. Specific corrections

    Say what is wrong, what must stay the same and how you will check it is fixed. “Make it nicer” is not enough.

  8. Save the working state

    Commit before a larger change and after each working feature. Without Git, make a dated copy of the folder.

  9. Publish early

    Online you see errors you do not see on your own machine: wrong paths, missing settings, the layout on a phone.

  10. Notes for next time

    Write down what works, what remains and how to run the tool. Start the next session from that note, not by continuing the old conversation.

12Prompting and good practices

No special phrases are needed. Explain the task as you would to a colleague: what you want, what you already have, what must not change and how you will both know the result is good.

Example: "The pricing table on this page is unreadable on a phone — rows squeeze together and the numbers get cut off. Keep every price and description, and change only the table layout below 480 px. Don't touch anything else. When you're done, show me a screenshot at 375 px."

A weak and a good correction2 examples

Weak: “Still ugly, make it nicer.” The model reinterprets the whole design. Better:

Keep all text and links. Remove cards and gradients.
One 760 px column, white background, blue only for links.
No horizontal overflow at 390 px (exception: the table).
Run it and show the changed files.

Which language to write in

Models understand Slovenian and answer fluently. Even so, the language you write in matters, for two reasons.

1. A smaller language costs far more tokens. The tokenizer was built mostly on English text. An English word is often one token; the same word in another language is often three or four, and accented letters are frequently tokens of their own. Oxford research found the same text can be up to 15 times longer in tokens across languages — considerably more expensive for the same content in some languages (Petrov et al., 2023). Your context window therefore fills faster and your limits run out sooner.

2. The model saw technical material almost exclusively in English. Documentation, library names, error messages and developer discussions are English. Written about in another language, the model translates as it goes and more often invents terms or gets grammar wrong.

In practice

Write technical instructions in English and ask for the output in your language. End the prompt with “answer in Slovenian”.

Do not translate error messages. Paste them unchanged; the model recognises them in their original form.

For everyday writing, summaries and questions, any well-supported language is fine. The difference shows in long technical sessions.

Good practices4 rules

Handling context (when to clear, how to batch corrections) is in chapter 10. Here are four more practices.

  • Have the agent read the project first. Then it does not write code for files and functions that do not exist.
  • Use the more expensive model only when the default fails on a clearly specified task.
  • A test is a lasting instruction. A rule written as a test holds in every later session.
  • Undo a wrong direction right away. More work on a wrong assumption only produces a more complicated mistake.

Review checklist: REVISION-CHECKLIST.md. Vendor guides: Anthropic, Google, Prompting Guide.

13Five common failures

Condensed from Avoid common failure patterns in Claude Code best practices. Each has a simple fix.

Five failures and their fixes5 failures
  1. Every task in one session

    You start one task, ask something unrelated, then return. Context is full of irrelevant information. Fix: /clear between unrelated tasks.

  2. Correcting in circles

    The model gets it wrong, you correct, it is still wrong. Context is polluted with failed approaches. Fix: after two failed corrections, start fresh with a better prompt.

  3. An overlong CLAUDE.md

    If the instruction file is too long, the model ignores part of it. For each line, ask: “Would removing this cause Claude to make mistakes?” If not, cut it.

  4. Trust without checking

    The model returns a solution that looks right but misses edge cases. The fix: “If you can't verify it, don't ship it.”

  5. Unbounded exploration

    You ask it to “investigate” with no limit. It reads many files and fills the context. Fix: scope the task narrowly, or use a subagent.

14Git

Git records project history locally. GitHub keeps a remote copy. Git is not required, but it is the fastest way back to a working version when an agent breaks several files at once.

A commit is a saved snapshot with a description. A branch is a parallel line of work. Push and pull synchronize with the remote copy (more on branches).

Basic commands6
  • .gitignorelist of files that stay out of history
  • git statuswhich files have changed
  • git diffreview changes before the commit
  • git add filenamechoose files for the next commit
  • git commit -m "..."save a snapshot
  • git pushsend to the remote copy
Why not git add .

git add . adds every file, including ones you did not notice: .env with keys, data exports, large files. Once a key is in the history on GitHub, deleting it is not enough; you have to replace it.

Write a .gitignore first, then add files by name (git add filename). Use git add . only once your .gitignore is in place and you have read git status.

Graphical client: GitHub Desktop. Learning: Learn Git Branching, GitHub Skills.

15Publishing to the web

This is how this page and every project above is published: push the repository to GitHub (it can be private) and, in Cloudflare Pages, connect the repository. Each push publishes a new version and each branch gets its own preview address. The *.pages.dev address works immediately, a custom domain is optional.

Build settings:

What the project isBuild settings
Plain HTML/CSS/JS
the files are ready as they are
Framework preset None, empty build command, output directory / or the folder holding the site.
A framework
Astro, Vite, React, Svelte…
Pick the framework preset; Cloudflare usually detects it. Astro, for example: command npm run build, output dist. For the rest see the framework guides.
OptionForNote
GitHub Pagesstatic sites, docsthe repo is public on the free plan
Cloudflare Pagesstatic and frontend from Gitlarge free tier, including private repos
Cloudflare WorkersAPIs, cron, secretsfree, then usage-based
Vercel / Netlifyfrontend frameworks, previewscheck the commercial limits
Supabasedatabase, auth, storagecheck who can read the data
Raspberry Pi / VPSprivate dashboards, scrapersmaintenance, backups, and failures are yours

An agent is a program with permissions

A coding agent can read files, run commands and open web pages. What it is allowed to do matters more for security than which model you use.

  • Give the agent only the permissions the task needs.
  • Read commands before you approve them.
  • Block reading of secrets: .env, private keys, certificates and credential files.
  • Review an unfamiliar repository first. Installing packages runs someone else's code.
  • What the agent reads is not a command. A web page or document can contain hidden instructions for the agent (prompt injection).
  • Run risky things separately: in a sandbox, a container or under a separate user.

Permission settings in Claude Code: security, permissions, configuration.

Security when publishing

Do not store API keys in code that runs in the browser or in a public repository. A server function should hold the key (encrypted secrets). Agents often write keys straight into the code, so review the diff before every commit.

16Sensitive data

Before you put personal, business or health data into a chat or project:

  • Check your organisation's rules and the provider's terms, including whether data is used to train models.
  • Where you can, anonymise the data or use a made-up sample with the same structure.
  • Do not send more than the task needs.

The strongest protection is a local model with no cloud connection. Run one with Ollama or LM Studio. Lower level: llama.cpp. Browser interface: Open WebUI.

A small local model is enough for classification, extraction, and summaries. For harder reasoning and long agent work, cloud models are still considerably better. Do not take the word “local” on trust: a local interface can still call web search, cloud embeddings, or telemetry. Check the settings and the network traffic.

17Glossary

LLM (large language model)
A model that builds text from learned patterns, not from a database of facts, so check facts.
Token
A chunk of text, roughly three quarters of an English word. Usage is measured in tokens.
Context window
Everything the model currently considers: messages, files, command output. It accumulates during a session until the system compacts or truncates it. See the section.
Coding agent
A program that reads and edits files locally, runs commands, and fixes its own errors — Claude Code, Codex.
Skill
A saved procedure in a SKILL.md file that loads only when used.
Subagent
A separate session with its own context that does the research and returns only a summary.
Prompt
The instruction you give the model. A good prompt clearly describes the task, the input and the result you want.
Diff
The list of changes between two versions of a file. Review it before you accept a change.
Multimodality
Input and output beyond text: images, PDFs, audio, video.
Commit
A saved snapshot of the project in Git, with a description of the changes. See the section.
Subscription vs API
A subscription pays for a person in the app; the API pays for calls from your code, by usage. See the section.

18Sources and further reading

Sources are also linked in the text. Checked September 2026. For prices and names, the provider's page applies.

Courses (free, official)6 sources
Working with agents and skills6 sources
Pricing, plans and choice4 sources
The term and first-hand accounts6 sources
Measurements3 sources
Tools4 sources