Nestia review 2026: how this open-source NestJS SDK generator creates type-safe clients, Swagger docs and mock APIs automatically. Features and pricing inside.
Nestia is an open-source TypeScript toolkit that plugs into the NestJS backend framework and turns existing controller code into a fully type-safe client SDK, an accurate OpenAPI or Swagger document, and a working mock server, all generated automatically from the TypeScript types already in the project.
Created and maintained by Jeongho Nam (known online as samchon), a Seoul-based developer, Nestia is distributed as a family of npm packages rather than sold as a commercial product. It is closely paired with typia, the same author's high-performance runtime validation library, which Nestia uses under the hood for both validation and mock data generation.
Nestia's flagship capability is generating a strongly typed client SDK straight from NestJS controllers, giving frontend and backend TypeScript code a shared, always-current contract without hand-written API clients. It pairs this with automatic Swagger and OpenAPI document generation, an SDK-embedded mock simulator for frontend development before the backend is finished, and an automatic end-to-end test generator.
On the performance side, at nestia/core swaps out class-validator and class-transformer for typia-powered validation and serialization, which the project reports as vastly faster in benchmarks. Nestia also includes a migration tool that can convert existing Swagger documents into NestJS controller scaffolding, easing adoption for teams migrating from other frameworks.
Nestia is completely free and open source with no paid tiers, usage limits, or license fees; teams install the npm packages directly into their NestJS project. The project accepts voluntary financial support through GitHub Sponsors, but this does not gate access to any feature.
Because there is no commercial vendor behind Nestia, support comes from the open-source community, GitHub issues, and the maintainer's own documentation and blog posts rather than a dedicated support contract or SLA.
Yes, Nestia is fully open source and free to use; there are no paid tiers.
Nestia is purpose-built for NestJS and works alongside its Express or Fastify adapters.
Nestia generates its SDK from existing NestJS REST controllers and OpenAPI conventions, while tRPC requires building procedures in a tRPC-specific router; Nestia can also emit standard Swagger documents.
Nestia is created and maintained by Jeongho Nam (samchon), a developer based in Seoul, South Korea, alongside open-source contributors.
Yes, at nestia/core replaces class-validator and class-transformer with typia-based validation and serialization for significant performance gains.
Yes, its SDK-embedded mockup simulator returns realistic random data that conforms to your DTO types, so frontend teams can develop against a fake backend.
Yes, Nestia includes a migration tool that can convert Swagger and OpenAPI documents into NestJS controllers and DTOs.