Zod vs Yup: Which Schema Validation Library?
Zod is a TypeScript-first validator that infers static types from schemas; Yup is an established, mature object schema library.
Zod is designed TypeScript-first: define a schema once and infer the static type automatically, with a clean chainable API and a fast-growing ecosystem (tRPC, React Hook Form, OpenAPI tooling). Yup predates Zod, is widely used (notably with Formik), and is solid, but its TypeScript inference is weaker and bolted on. Zod wins on type inference, DX, and momentum; Yup wins as a familiar choice in existing Formik-based stacks.
| Zod | Yup | |
|---|---|---|
| TypeScript | First-class inference | Weaker, retrofitted |
| API | Chainable, modern | Chainable, mature |
| Ecosystem | Large, growing fast | Established |
| Static types | Inferred (z.infer) | Manual / partial |
| Best for | TypeScript-first projects | Existing Formik/Yup stacks |
Use case and types
Zod suits TypeScript projects wanting one source of truth: a schema that also produces the static type, with rich integrations. Yup suits teams already using it (often via Formik) or JS-first projects where its maturity is enough. For new TypeScript work, Zod's inference is a decisive advantage.
Testing and CI
Both validate inputs deterministically and unit test cleanly. Either runs on managed runners, where faster runners shorten validation and form-logic test suites.
The verdict
Building TypeScript-first with inferred types and modern integrations: Zod. Maintaining a Formik/Yup stack or JS-first project: Yup is fine. For new TypeScript projects, Zod is the recommended default.