Get started

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 convention:

File	Content	When to use it
`/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`	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. 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);
GET https://api.fathomcharts.com/v1/instruments, with an API key: the instruments and their tick size (see Instruments);
GET https://api.fathomcharts.com/v1/offers, no authentication: the offers and their limits (see Limits);
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):

## 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).