Short answer

What to know

Choose Mockaroo when you need custom fields, generated records, large datasets or configurable mock routes. Choose Payloads when a tiny public fixture, stable URL, cross-format equivalence and no account or API key are more important than customization.

The short comparison

NeedPayloadsMockaroo
Use immediately without an accountYesWebsite generation is available; API access uses a key
Design custom fieldsNoYes
Generate many recordsNo; deliberately smallYes
Stable public fixture URLsYesSaved/generated workflows
MessagePack and CBOR fixturesYesNot documented API output formats
Programmable mock routesNoYes

Choose Mockaroo for data generation

Mockaroo is designed for specifying fields and generating realistic records. Its documented APIs can generate data from supplied or saved schemas, and its mock API product can model routes and request-dependent behaviour.

Choose Payloads for a fixed shared fixture

Payloads requires no setup because there is nothing to configure. The trade-off is that the dataset is fixed. That is useful for examples, regression tests and teams that want to refer to the same small input by URL.

Primary reference