NestJS

Nestia is the NestJS integration layer built on top of typia. It replaces the usual class-validator + @nestjs/swagger setup with decorators that read your TypeScript interfaces directly — no DTO classes, no decorator soup.

It ships four packages:

Package	What it does
`@nestia/core`	Superfast NestJS decorators backed by typia (`@TypedBody`, `@TypedRoute`, `@TypedQuery`, …)
`@nestia/sdk`	Evolved SDK and Swagger generators that read NestJS controllers and emit type-safe client code
`@nestia/migrate`	Swagger → NestJS scaffolding
`nestia`	CLI for the above

Minimal controller


import { Controller } from "@nestjs/common";
import { TypedBody, TypedRoute } from "@nestia/core";
 
import type { IBbsArticle } from "@bbs-api/structures/IBbsArticle";
 
@Controller("bbs/articles")
export class BbsArticlesController {
  /**
   * Store a new content.
   *
   * @param input Content to store
   * @returns Newly archived article
   */
  @TypedRoute.Post()                          // ~200x faster, type-safe JSON.stringify
  public async store(
    @TypedBody() input: IBbsArticle.IStore,   // ~20,000x faster validator
  ): Promise<IBbsArticle> {
    /* … no DTO class. Plain interface works. */
  }
}

The decorators are interchangeable with the standard NestJS ones — same shape, same testing approach, much less boilerplate. @TypedBody validates with typia.assert and @TypedRoute serializes with typia.json.assertStringify.

Incremental adoption

You can add @TypedBody / @TypedRoute to a single route without touching the rest of the codebase. Specifically:

@TypedBody and @Body coexist on different routes of the same controller. Existing class-validator-decorated DTOs keep working; you migrate route by route.
The build still uses tsc — but it must be the ts-patch-patched tsc. Add the legacy setup (wizard or manual) once, and from then on your existing npm run build keeps the same shape. CI pipelines that run npm ci --ignore-scripts need an explicit npx ts-patch install after install — see the CI tip on the Legacy setup page.
@nestia/sdk runs alongside @nestjs/swagger during migration. The two generators emit different artifacts (typed client SDK vs Swagger JSON), so you can keep @nestjs/swagger until every controller is on @TypedRoute, then drop it.

SDK generation

@nestia/sdk reads the same controller files and emits a typed client SDK plus a Swagger document. The TypeScript types you wrote on the server become the request/response types on the client, automatically.

nestia-sdk-demo

Left: NestJS server code
Right: Client code using the generated SDK

Where to go next

Full Nestia docs: nestia.io
The underlying validator/serializer pair: assert · json.assertStringify
LLM agents that drive a Nestia backend: Agentica