Postman Echo vs US Street Address

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.

Smarty's US Street API is a CASS-certified single/batch address validator: it corrects, standardizes, and appends ZIP+4, county, carrier route, and delivery-point-validation (DPV) data to a US postal address, flagging vacant, undeliverable, or CMRA (commercial mail receiving agency) addresses along the way. Requests can be sent as GET query parameters or as a JSON/XML batch of up to 100 addresses per POST, and responses are returned in the same format. It shares an account and API key with Smarty's other address-data products, including US Autocomplete and US Extract.