fitbit-metrics`.maxhogan.dev`

Convert Fitbit health data into Prometheus metrics.

Cloudflare Worker that exposes Fitbit health data as a Prometheus-compatible /metrics endpoint. Includes sleep, RHR, HR zone, HRV, skin temp, SpO2, calories, steps, distance, & floors. Built with Hono + TS.

Requirements

Prometheus
A Fitbit account

Steps

Authorize this app with your Fitbit account
Save the API token returned from step 1
Configure your Prometheus server to scrape /metrics using your saved API token (using Authorization: Bearer abcd1234-... header or ?token=abcd1234-...)

- job_name: fitbit
  scrape_interval: 15m
  scheme: https
  authorization:
    type: Bearer
    credentials: "abcd1234-..."
  static_configs:
    - targets: ["fitbit-metrics.maxhogan.dev"]

Metrics are cached for 12 hours on the server-side, so scrape_interval can be pretty aggressive if you want but updated data may be delayed.

Historical backfill (`?daysAgo=`)

/metrics returns the most recent 30 days by default. Pass ?daysAgo=N to shift the 30-day window N days further into the past — e.g. ?daysAgo=30 returns the 30 days before the default window, ?daysAgo=60 the 30 before that, and so on. This lets you backfill older history one window at a time. daysAgo defaults to 0 (the current behavior) and must be a non-negative integer. Historical windows (daysAgo>0) are immutable, so they're cached longer (7 days) than the current window.

Metrics

All metrics are Prometheus gauges, labeled by date (and additional labels where noted). Data covers the last 30 days per scrape.

Metric	Description	Labels
`fitbit_sleep_hours_asleep`	Total hours asleep	`date`
`fitbit_sleep_hours_in_bed`	Total hours in bed	`date`
`fitbit_sleep_efficiency`	Sleep efficiency score (0–100)	`date`
`fitbit_sleep_stage_minutes`	Minutes in each sleep stage	`date`, `stage`
`fitbit_resting_heart_rate`	Resting heart rate (bpm)	`date`
`fitbit_heart_rate_zone_minutes`	Minutes in each HR zone	`date`, `zone`
`fitbit_hrv_daily_rmssd`	Daily RMSSD HRV (ms)	`date`
`fitbit_hrv_deep_rmssd`	Deep-sleep RMSSD HRV (ms)	`date`
`fitbit_skin_temp_nightly_relative`	Skin temp deviation from baseline (°C)	`date`
`fitbit_spo2_avg`	Average SpO2 %	`date`
`fitbit_spo2_min`	Minimum SpO2 %	`date`
`fitbit_spo2_max`	Maximum SpO2 %	`date`
`fitbit_breathing_rate`	Breathing rate (breaths/min)	`date`
`fitbit_steps`	Daily step count	`date`
`fitbit_calories`	Daily calories burned	`date`
`fitbit_distance`	Daily distance (km)	`date`
`fitbit_distance_mi`	Daily distance (miles)	`date`
`fitbit_floors`	Daily floors climbed	`date`

Routes

Route	Auth	Description
`GET /authorize`	None	Starts Fitbit OAuth2 flow
`GET /callback`	Via state	OAuth2 callback, returns your API token
`GET /metrics`	Bearer	Prometheus scrape endpoint (`?daysAgo=N` for history)
`GET /purge`	Bearer	Clears the KV response cache for your account
`GET /doc`	None	OpenAPI 3.0 JSON spec
`GET /reference`	None	Scalar API reference UI
`GET /llms.txt`	None	Plain text README for LLMs

Development

Setup

npm install

Secrets

Variable	Description
`FITBIT_CLIENT_ID`	Fitbit app client ID
`FITBIT_CLIENT_SECRET`	Fitbit app client secret

npx wrangler secret put FITBIT_CLIENT_ID
npx wrangler secret put FITBIT_CLIENT_SECRET

Dev

npx wrangler dev

Deploy

npx wrangler deploy

fitbit-metrics.maxhogan.dev