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OAuth2 REST API
Clients, invoices, expenses, payments, projects, time entries, estimates, credit notes
OAuth2 authorization code flow. Access tokens expire in 1 hour; refresh tokens are long-lived. AccountID and BusinessID both required for full API coverage.
- Go to my.freshbooks.com/#/developer and click Create App.
- Set the Redirect URI to your app’s callback URL (e.g. https://yourdomain.com/FreshBooksCallback.aspx) and save.
- Copy your Client ID and Client Secret from the app page and paste them into Account Settings, then click Save Account.
- Click Connect FreshBooks in Account Settings — you will be redirected to FreshBooks to authorise. Upon return the AccountID and BusinessID are auto-populated.
Collect: Client ID · Client Secret · (AccountID & BusinessID are auto-discovered after Connect)