Trestle RETS
Trestle's legacy Real Estate Transaction Standard interface, documented as compliant with RETS 1.8. RESO no longer updates the RETS specification, but Trestle continues to serve it for customers who cannot move to the Web API. Login is POST /trestle/rets/login; the service is session-less and supports either HTTP Basic with a Base64-encoded client_id:client_secret or an OAuth2 bearer token obtained with scope=rets. Digest authentication is explicitly not supported.