Short answer
What to know
Choose JSONPlaceholder when you need familiar REST resources and simulated POST, PUT, PATCH or DELETE requests. Choose Payloads when you need small immutable files, checksums or the same records in JSON, XML, CSV, YAML, NDJSON, MessagePack, CBOR and PDF.
The short comparison
| Need | Payloads | JSONPlaceholder |
|---|---|---|
| Read stable JSON | Yes | Yes |
| XML, CSV and binary formats | Yes | No; JSON API |
| Simulated write methods | No | Yes |
| Published byte checksums | Yes | Not its main contract |
| Large familiar REST resources | No; deliberately tiny | Yes |
| Runtime backend | No; static files | Yes |
Choose JSONPlaceholder for REST-shaped prototypes
JSONPlaceholder presents posts, comments, albums, photos, todos and users through familiar routes. Its guide demonstrates reads as well as simulated writes, which makes it convenient for tutorials and interfaces shaped around REST operations.
Choose Payloads for fixture and parser tests
Payloads is intentionally less API-like. Its versioned files are useful when the important property is a known response body, exact media type, cross-format equivalence or a checksum—not server behaviour.