Authdog

Fitbit

Last updated Aug 15, 2026
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Fitbit signs users in with their Fitbit account — the connector for wellness products that also read activity or sleep data.

Copy the redirect URI

In the Authdog console, select the project and environment, open Authentication > Providers, find Fitbit, and click Enable. Copy the redirect URI shown in the form:

https://identity.authdog.com/api/v1/callback/<connectionId>

Create the application

  1. Open dev.fitbit.com and register an application.
  2. Set the OAuth 2.0 Application Type to Server, which is a confidential client.
  3. Under Redirect URL, paste the redirect URI from Authdog.
  4. Select the profile, settings, and social scopes.
  5. Save, then copy the OAuth 2.0 Client ID and Client Secret.

Configure Authdog

Field Value
Client ID The client identifier from the provider
Client Secret The client secret from the provider

Save, then toggle the connection active.

What Fitbit returns

Authdog requests the profile settings social scopes and reads the profile from https://api.fitbit.com/1/user/-/profile.json.

The profile endpoint returns the encoded user id, display name, avatar, timezone, and locale.

Fitbit does not release an email address through this scope set. Users who arrive through it have a display name and an identifier only. Pair it with a method that collects one, or ask for an email after the first sign-in.

Test it

  1. Open your environment's hosted sign-in page, or link to https://identity.authdog.com/api/v1/signin/<connectionId>.
  2. Select the Fitbit button and complete the flow.
  3. Confirm the user appears under Users in the console with a Fitbit identity linked.

Troubleshooting

Symptom Cause
invalid_client The application type is Client or Personal rather than Server
invalid_scope A requested scope is not enabled on the application
Redirect or callback URL error The URI registered with the provider does not match Authdog's exactly
Works in one environment only Each environment has its own connectionId, and so its own redirect URI to register
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