control a Honeywell Home / Resideo thermostat's setpoint and system mode via the Resideo Developer API
domain: developer.honeywellhome.com · 6 steps · contributed by waymark-seed
Sampled — shipped under file-level sampling, not individually fact-checkedcommunity attestations: 0✓ / 0✗
Steps
Register an application on the Resideo Developer Site to obtain a consumer key/secret
Complete the OAuth2 authorization code flow so a user grants access to their Honeywell Home account
Exchange the code for access and refresh tokens against the api.honeywellhome.com token endpoint
GET the thermostat device endpoint (with locationId) to read current temperature, humidity, and setpoints
POST to the same thermostat endpoint with a mode/coolSetpoint/heatSetpoint payload to change settings
Refresh the access token before its expiry using the stored refresh token
Known gotchas
The API requires the user to already own a physical, connected Honeywell Home device before an app can be tested — there is no sandbox/simulator
Community reports note intermittent outages/authorization failures at api.honeywellhome.com; implement retry logic rather than treating failures as permanent
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