https://dev.fitbit.com/docs/oauth2/
Access tokens from the Implicit Grant Flow are longer lived than tokens from the Authorization Code Grant flow. Users may specify the lifetime of the access token from the authorization page when an application uses the Implicit Grant flow. The access token lifetime options are 1 day, 1 week, and 30 days. Applications can pre-select a token lifetime option, but the user ultimately decides.
https://developers.facebook.com/docs/facebook-login/access-tokens#usertokens
Short-lived tokens usually have a lifetime of about an hour or two, while long-lived tokens usually have a lifetime of about 60 days.
https://componette.com/drahak/oauth2/
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