FreshBooks API

Create or log into a FreshBooks account, then open the Developer hub. Select Apps → Create New App, enter the app name, application type, redirect URI(s), and any needed scopes, then save. FreshBooks issues a client_id and client_secret for the app. To call the API, send users through the FreshBooks OAuth 2.0 authorization code flow from the app's authorization URL, then exchange the returned code at https://api.freshbooks.com/auth/oauth/token for an access token and refresh token as described in the Authentication docs.