Build on your Fitaio data

A REST API with personal keys, and an MCP server so AI assistants can read your training and log for you. Free, like the app.

Quickstart

Create a key, make your first request, page through workouts, log one.

MCP server

22 tools, 14 read and 8 write, for Claude, ChatGPT, Cursor and VS Code.

API reference

Every endpoint, parameter and schema, generated from the OpenAPI document.

Get a key

Open Fitaio, go to Settings, then Developer (or open the Developer screen in the web app).
Create a key with read or read and write scope. You can hold up to 10.
Copy it once. Keys look like fitaio_ followed by 40 characters. Revoke any key from the same screen.

Authenticate

Send the key as a bearer token:

curl https://fitaio.app/api/v1/me \
  -H "Authorization: Bearer fitaio_YOUR_KEY"

The api-key: fitaio_YOUR_KEY header works as well, so tools written for Hevy’s API can point here unchanged.

Key facts

Base URL	`https://fitaio.app/api/v1`
Format	JSON, `snake_case` fields
Units	kilograms, centimetres, kilocalories, grams
Time	RFC 3339 in UTC for timestamps, `YYYY-MM-DD` for days
Pagination	`limit` 1 to 100 (default 25) and `next_cursor`
Limits	120 requests a minute per key, 300 per IP, request bodies up to 256 KB
Errors	`{ "error": { "code", "message", "details" } }`

What you can reach

Resource	Path	What it holds
Me	`/me`	The account behind the key.
Workouts	`/workouts`	Logged sessions with exercises and sets; create, update, delete, count and change events.
Routines	`/routines`	Reusable single-day templates.
Training plans	`/plans`	Weekly plans, one active at a time.
Exercises	`/exercises`	The catalogue, one exercise, and your history per exercise.
Body	`/body/weight`	Weight and body-fat logs, tape measurements.
Nutrition	`/nutrition`	Daily calories and macros by day.
Supplements	`/supplements`	Schedule and daily ticks.
Goals	`/goals`	Body goals; the newest is current.
Stats	`/stats/training`	Training totals by muscle group, personal records, body trend.

Not in v1

Meal plans, progress photos, community and the AI coach are app-only for now. Deleting a workout produces no event; poll /workouts/events for updates.