cronometer-api-mcp
Hosted version for Claude.ai, ChatGPT, and Grok coming soon. Join the waitlist →
An MCP (Model Context Protocol) server for Cronometer nutrition tracking, built on the reverse-engineered mobile REST API.
Unlike cronometer-mcp, which takes a comprehensive GWT-RPC approach against Cronometer's web backend, this server talks to the same JSON REST API used by the Cronometer Android app -- with clean payloads and stable, versioned endpoints.
Features
- Food log -- diary entries with food names, amounts, meal groups
- Nutrition data -- daily macro/micro totals and nutrition scores with per-nutrient confidence
- Food search -- search the Cronometer food database, get detailed nutrition info
- Diary management -- add/remove entries, copy days, mark days complete
- Custom foods -- create foods with custom nutrition data
- Macro targets -- read weekly schedule and saved templates
- Fasting -- view history and aggregate statistics
- Biometrics -- weight, body fat, heart rate, and other tracked metrics over a date range
Quick Start
1. Install uv
curl -LsSf https://astral.sh/uv/install.sh | sh
2. Set credentials
export CRONOMETER_USERNAME="your@email.com"
export CRONOMETER_PASSWORD="your-password"
Optional: override the account timezone
Diary entries are stamped in your Cronometer account's timezone, which the server reports at login. If that zone is wrong (for example, an older build had reset it) you can force a specific IANA zone without changing your account settings:
export CRONOMETER_ACCOUNT_TZ="America/Los_Angeles"
When set, this takes precedence over both the value reported at login and any cached session, so it also overrides a stale cached timezone.
3. Configure your MCP client
uvx downloads and runs the server on demand -- no separate install step.
OpenCode (opencode.json)
{
"$schema": "https://opencode.ai/config.json",
"mcp": {
"cronometer": {
"type": "local",
"command": ["uvx", "cronometer-api-mcp"],
"environment": {
"CRONOMETER_USERNAME": "{env:CRONOMETER_USERNAME}",
"CRONOMETER_PASSWORD": "{env:CRONOMETER_PASSWORD}"
},
"enabled": true
}
}
}
Claude Desktop (claude_desktop_config.json)
{
"mcpServers": {
"cronometer": {
"command": "uvx",
"args": ["cronometer-api-mcp"],
"env": {
"CRONOMETER_USERNAME": "your@email.com",
"CRONOMETER_PASSWORD": "your-password"
}
}
}
}
Available Tools
Food Log & Nutrition
| Tool | Description |
|---|---|
get_food_log | Diary entries for a date, each enriched with food name, source, serving measure/count, and that food's per-entry nutrient contribution, plus an energy_summary (target/consumed/remaining kcal) and a nutrition_summary of consumed totals for every tracked nutrient |
get_daily_nutrition | Consumed macro and micronutrient totals for every nutrient tracked in Cronometer |
get_nutrition_scores | Category scores (Vitamins, Minerals, etc.) with per-nutrient consumed amounts and confidence levels |
Food Search & Details
| Tool | Description |
|---|---|
search_foods | Search the Cronometer food database by name |
get_food_details | Full nutrition profile and serving sizes for a food |
Diary Management
| Tool | Description |
|---|---|
add_food_entry | Log a food serving to the diary |
remove_food_entry | Remove one or more diary entries |
add_custom_food | Create a custom food with specified nutrition |
copy_day | Copy all entries from the previous day |
mark_day_complete | Mark a diary day as complete or incomplete |
Targets & Tracking
| Tool | Description |
|---|---|
get_macro_targets | Weekly macro schedule and saved target templates |
get_fasting_history | Fasting history within a date range |
get_fasting_stats | Aggregate fasting statistics |
list_biometrics | List trackable biometric metrics and their units |
get_biometrics | Biometric time series (e.g. weight, body fat) within a date range |
All date parameters use YYYY-MM-DD format and default to today when omitted.
Transport
stdio only. For remote/hosted use, the stdio server is wrapped by
supergateway (see Dockerfile),
which owns the HTTP listener and exposes MCP streamable-HTTP at /mcp. The
server has no built-in authentication — any remote deployment must sit
behind an authenticating gateway or reverse proxy.
Development
For local development, copy .env.example to .env and fill in your credentials:
cp .env.example .env
# edit .env
uv run cronometer-api-mcp
The CLI auto-loads .env on startup (dev convenience only). Real environment variables always win over .env, so production deployments and MCP client env blocks are unaffected.
How It Works
This server communicates with mobile.cronometer.com -- the same REST API used by the Cronometer Android/Flutter app. The API was reverse-engineered through:
- Static analysis of
libapp.so(Dart AOT snapshot) from the APK to discover endpoint names - Traffic interception via Frida + mitmproxy to capture exact request/response formats
- Trial-and-error against the live API to confirm payload shapes
The API uses two protocols:
- v2 (
POST /api/v2/*) -- JSON-body auth, used for most operations (food search, diary read/write, nutrition, fasting, macros, biometrics) - v3 (
DELETE /api/v3/user/{id}/*) -- Header-based auth (x-crono-session), used for diary entry deletion
Python API
You can use the client directly:
from cronometer_api_mcp.client import CronometerClient
from datetime import date
client = CronometerClient()
# Search for foods
results = client.search_food("chicken breast")
# Get food details
food = client.get_food(results[0]["id"])
# Log a serving
client.add_serving(
food_id=food["id"],
measure_id=food["defaultMeasureId"],
grams=200,
)
# Get today's diary
diary = client.get_diary()
# Get nutrition scores
scores = client.get_nutrition_scores()
License
MIT