# Use with an LLM

The whole documentation is available as Markdown, the format AI assistants and coding agents (Claude, ChatGPT, Claude Code, Cursor, Codex…) read best. Point them at it: they write your integration from the current API, not from memory.

## On every page

At the top of each documentation page:

- **Copy page** copies the page as Markdown, ready to paste into a conversation;
- **Markdown** opens the Markdown version of the page;
- **Open in Claude** and **Open in ChatGPT** start a conversation that reads the page, so you can ask your questions right away.

## llms.txt

Two files at the root of the site follow the [llms.txt](https://llmstxt.org) convention:

| File                                                       | Content                                                                                                              | When to use it                           |
| ---------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------- | ---------------------------------------- |
| [`/llms.txt`](https://fathomcharts.com/llms.txt)           | Index: every page with a one-line summary, linking to its Markdown version, plus the machine-readable API references | Let the agent pick the pages it needs    |
| [`/llms-full.txt`](https://fathomcharts.com/llms-full.txt) | The whole English documentation in a single file, indicator pages included                                           | Load everything into the context at once |

## Markdown pages

Append `.md` to the address of any documentation page to get its Markdown version:

```bash
curl https://fathomcharts.com/en/docs/quickstart.md
```

Agents that send `Accept: text/markdown` (Claude Code, Cursor…) get the Markdown directly at the usual address:

```bash
curl -H "Accept: text/markdown" https://fathomcharts.com/en/docs/quickstart
```

French pages work the same way: [`/docs/demarrage-rapide.md`](https://fathomcharts.com/docs/demarrage-rapide.md.md). Links between Markdown pages point to Markdown pages, so an agent can follow them.

## Machine-readable references

Beyond the documentation, the API describes itself:

- `GET https://api.fathomcharts.com/v1/indicators`, no authentication: every indicator with the JSON Schemas of its parameters and of its data (see [Indicators](https://fathomcharts.com/en/docs/indicators.md));
- `GET https://api.fathomcharts.com/v1/instruments`, with an API key: the instruments and their tick size (see [Instruments](https://fathomcharts.com/en/docs.md#instruments));
- `GET https://api.fathomcharts.com/v1/offers`, no authentication: the offers and their limits (see [Limits](https://fathomcharts.com/en/docs/limits.md));
- `https://api.fathomcharts.com/docs/json`, no authentication: the OpenAPI 3.1 description of the REST API.

## Instructions for your coding agent

Paste this block into the `AGENTS.md` file of your project (read by Codex, Cursor and most agents) or into `CLAUDE.md` (Claude Code):

```md
## Fathom Charts API

- Before writing code against the Fathom Charts API, read the documentation index https://fathomcharts.com/llms.txt and the Markdown pages it links to. Do not rely on memory.
- Indicator parameters and data shapes: the JSON Schemas of GET https://api.fathomcharts.com/v1/indicators.
- Use the TypeScript SDK `@fathom-charts/sdk` for real-time streams and history pagination.
- The API key comes from the `FATHOM_CHARTS_API_KEY` environment variable, server-side only: never in code that runs in a browser.
```

## Good to know

- The Markdown pages are generated from the same source as the HTML pages, with every release: they always say the same thing.
- Never paste an API key into a conversation with an assistant: give it the name of the environment variable instead (see [Authentication](https://fathomcharts.com/en/docs/authentication.md)).