For developers. Just want to ask Claude about your training, with no code? Start with Your Garmin data in Claude instead.

In my first post I introduced garminconnect-js , a typed, zero-dependency Garmin Connect client for Node. This series is the hands-on version: four posts that take you from an empty folder to an app that reads and writes Garmin data.

This first part covers the foundation everything else stands on:

Signing in, including two-factor (MFA) codes

Keeping the session, so you sign in once and not on every run

Reading data, and what "no data" looks like

Handling errors properly

By the end you'll have a small command-line script that prints last night's sleep and HRV.

Written against garminconnect-js 0.10.0 . Every snippet here type-checks against that version.

What you need

Node 18 or newer ( node --version )

A Garmin Connect account with some data in it.…