Fishery vs YData Synthetic

Fishery is a free JavaScript library for preparing objects as test data and for other situations where JavaScript data needs setup. Its factories define defaults, and build() creates objects with supplied parameters layered over those defaults. TypeScript users can obtain typed factory parameters and return objects, while the library also works without TypeScript. Factories may define onCreate behavior for asynchronous work; create() then performs that work and returns a promise. Additional factory capabilities include sequences, transient parameters, associations, and hooks that run after building or creating objects. Developers can extend factories with reusable builder methods by subclassing Factory. The documentation describes using factories alongside other factories to build associated objects. Installation instructions cover npm and Yarn as development dependencies. The repository identifies Fishery as free software under the MIT license and says thoughtbot, inc. maintains and funds it. GitHub Issues is the listed channel for bug reports and change requests.

YData Synthetic has no write-up on Specifiction yet; its figures are above.