nestia

nestia is a ttsc-powered toolkit for NestJS that turns your TypeScript controllers into type-safe SDKs, OpenAPI documents, E2E test scaffolding, and migration assets — generated at build time from the controller’s actual TypeScript signatures.

It builds on typia: every payload validator, every JSON serializer, every random fixture in a generated SDK uses typia’s compile-time transform. nestia shares the same ttsc plugin protocol and the same compilerOptions.plugins[] wiring.

Install


npm install -D ttsc @typescript/native-preview typia @nestia/core @nestia/sdk

That’s it. Both typia and @nestia/core ship the ttsc.plugin auto-discovery marker, so ttsc picks them up the moment they appear in dependencies / devDependencies — no compilerOptions.plugins[] entry needed.

Run ttsc --emit (or any ttsc / ttsx / unplugin bundler). The build replaces @nestia/core decorators with type-aware validators and serializers, and the nestia CLI consumes the same TypeScript types to generate SDKs and docs.

What it generates

A typical NestJS controller written for nestia:


import { TypedBody, TypedRoute } from "@nestia/core";
import { Controller } from "@nestjs/common";
 
@Controller("users")
export class UserController {
  @TypedRoute.Post()
  async create(@TypedBody() body: IUser.ICreate): Promise<IUser> {
    return /* ... */;
  }
}

Without any schema duplication you get:

Type-safe SDK — npx nestia sdk produces an npm-publishable client; await sdk.user.create(connection, body) is fully typed against the controller signature, including narrowed response types.
Swagger / OpenAPI — npx nestia swagger emits OpenAPI 3.1 (and Swagger 2.0) documents derived from the exact controller types, including typia tags (Format<"email">, Maximum<150>, …).
E2E test stubs — npx nestia e2e scaffolds Jest/E2E test files per route, calling the generated SDK.
Migration assets — npx nestia template, npx nestia setup — bootstrap pipelines and Swagger-to-controller migration.

The runtime decorators (@TypedBody, @TypedRoute.*, @TypedParam, @TypedQuery, …) replace the standard NestJS pipes with typia-generated validators — 20,000× faster than class-validator according to nestia’s benchmarks, and impossible to drift from the type because there is no parallel schema.

Why `ttsc`

@nestia/core is a TypeScript compiler transformer (it rewrites decorator calls at compile time), and typia is too. Stock tsc does not run user transformers; ttsc is one of the supported hosts. Both packages are auto-discovered from package.json (no compilerOptions.plugins[] entry needed) — ttsc resolves, builds, and caches each sidecar, then routes the TypeScript-Go AST through them in order.

The full pipeline runs everywhere ttsc runs — ttsc --emit, ttsx, the VS Code extension, every @ttsc/unplugin bundler adapter. One install; the transforms fire wherever NestJS code is compiled.

Combine with other ttsc plugins

nestia + typia compose because both are typia-aware (they share the typia compiler host under the hood). They also compose with @ttsc/lint, @ttsc/banner, @ttsc/paths, and @ttsc/strip in the same compilerOptions.plugins[] array. For combining unrelated executable transform hosts, see Plugin protocol → Combining plugins from different vendors.

Reference

nestia ships on its own release schedule with extensive docs.

Documentation: nestia.io
Source: github.com/samchon/nestia
E-Book: nestia.io/docs/pure — pure-TypeScript backend patterns with nestia.
Examples: github.com/samchon/nestia/tree/master/test — runnable E2E projects.