Lob.com vs Postman Echo

Lob's US Address Verification API checks, standardizes, and CASS-certifies a US postal address in real time, returning delivery-point-validation flags, vacancy and building-type metadata, and a corrected/deliverable address in one JSON response. It's the same verification engine behind Lob's broader direct-mail automation platform (mail creation, printing, and USPS tracking), so a key created for one Lob product works across the rest. Authentication is a single API key sent as the HTTP Basic Auth username, with separate test and live keys so integrations can be built and tested before any usage is billed.

Postman Echo is a keyless sandbox that mirrors whatever you send it back as JSON — headers, query args, form body, cookies, and basic/digest auth attempts — across GET, POST, PUT, DELETE, and PATCH endpoints, plus helpers for testing redirects, delays, streaming, and gzip/deflate encoding. It's built and maintained by the Postman team as the reference backend for their own client tutorials and public collections, so its request/response shapes double as worked examples. There's no signup or key: every route is open, making it a quick target for scripting HTTP-client tests without standing up your own server.