baseinc/next-rest-framework

Next REST Framework

Type-safe, self-documenting APIs for Next.js

Table of contents
Overview
Features
- Lightweight, type-safe, easy to use
Installation
Getting started
- Create docs handler
  - App Router:
  - Pages Router:
- Create endpoint
  - REST
  - RPC
API reference
CLI
Changelog
Contributing
License

Overview

Next REST Framework is an open-source, opinionated, lightweight, easy-to-use set of tools to build type-safe, self-documenting APIs with Next.js. Building OpenAPI specification-compliant APIs can be cumbersome and slow but Next REST Framework makes this easy with auto-generated OpenAPI documents and docs using TypeScript and object schemas.

This is a monorepo containing the following packages / projects:

The primary next-rest-framework package
An example application for live demo and local development

Features

Lightweight, type-safe, easy to use

Designed to work with TypeScript so that your requests and responses are strongly typed.
Supports API endpoints using both RESTful and RPC principles.
Object-schema validation with Zod. The object schemas are automatically converted to JSON schema format for the auto-generated OpenAPI specification.
Auto-generated and extensible openapi.json spec file from your business logic.
Auto-generated Redoc and/or SwaggerUI documentation frontend.
Works with Next.js Middleware and other server-side libraries, like NextAuth.js.
Supports both Next.js App Router and Pages Router, even at the same time.
Fully customizable and compatible with any existing Next.js project.

Installation

npm install next-rest-framework

Getting started

Create docs handler

To get access to the auto-generated documentation, initialize the docs endpoint somewhere in your codebase. You can also skip this step if you don't want to expose a public API documentation.

App Router:

// src/app/api/route.ts

import { docsRoute } from 'next-rest-framework';

export const { GET } = docsRoute();

Pages Router:

// src/pages/api.ts

import { docsApiRoute } from 'next-rest-framework';

export default docsApiRoute();

This is enough to get you started. Now you can access the API documentation in your browser. Calling this endpoint will automatically generate the openapi.json OpenAPI specification file, located in the public folder by default. You can also configure this endpoint to disable the automatic generation of the OpenAPI spec file or use the CLI command npx next-rest-framework generate to generate it. You can also create multiple docs endpoints for various use cases. See the full configuration options of this endpoint in the Docs handler options section.

Create endpoint

REST

App Router:

// src/app/api/todos/route.ts

import { TypedNextResponse, route, routeOperation } from 'next-rest-framework';
import { z } from 'zod';

const TODOS = [
  {
    id: 1,
    name: 'TODO 1',
    completed: false
  }
];

// Example App Router route handler with GET/POST handlers.
export const { GET, POST } = route({
  getTodos: routeOperation({
    method: 'GET',
    // Optional OpenAPI operation documentation.
    openApiOperation: {
      tags: ['example-api', 'todos', 'app-router']
    }
  })
    // Output schema for strictly-typed responses and OpenAPI documentation.
    .outputs([
      {
        status: 200,
        contentType: 'application/json',
        schema: z.array(
          z.object({
            id: z.number(),
            name: z.string(),
            completed: z.boolean()
          })
        )
      }
    ])
    .handler(() => {
      // Type-checked response.
      return TypedNextResponse.json(TODOS, {
        status: 200
      });
    }),

  createTodo: routeOperation({
    method: 'POST',
    // Optional OpenAPI operation documentation.
    openApiOperation: {
      tags: ['example-api', 'todos', 'app-router']
    }
  })
    // Input schema for strictly-typed request, request validation and OpenAPI documentation.
    .input({
      contentType: 'application/json',
      body: z.object({
        name: z.string()
      })
    })
    // Output schema for strictly-typed responses and OpenAPI documentation.
    .outputs([
      {
        status: 201,
        contentType: 'application/json',
        schema: z.string()
      },
      {
        status: 401,
        contentType: 'application/json',
        schema: z.string()
      }
    ])
    .middleware(
      // Optional middleware logic executed before request validation.
      (req) => {
        if (!req.headers.get('authorization')) {
          // Type-checked response.
          return TypedNextResponse.json('Unauthorized', {
            status: 401
          });
        }
      }
    )
    .handler(async (req) => {
      const { name } = await req.json(); // Strictly-typed request.

      // Type-checked response.
      return TypedNextResponse.json(`New TODO created: ${name}`, {
        status: 201
      });
    })
});

The TypedNextResponse ensures that the response status codes and content-type headers are type-checked. You can still use the regular NextResponse if you prefer to have less type-safety.

Pages Router:

// src/pages/api/todos.ts

import { apiRoute, apiRouteOperation } from 'next-rest-framework';
import { z } from 'zod';

const TODOS = [
  {
    id: 1,
    name: 'TODO 1',
    completed: false
  }
];

// Example Pages Router API route with GET/POST handlers.
export default apiRoute({
  getTodos: apiRouteOperation({
    method: 'GET',
    // Optional OpenAPI operation documentation.
    openApiOperation: {
      tags: ['example-api', 'todos', 'pages-router']
    }
  })
    // Output schema for strictly-typed responses and OpenAPI documentation.
    .outputs([
      {
        status: 200,
        contentType: 'application/json',
        schema: z.array(
          z.object({
            id: z.number(),
            name: z.string(),
            completed: z.boolean()
          })
        )
      }
    ])
    .handler((_req, res) => {
      // Type-checked response.
      res.status(200).json(TODOS);
    }),

  createTodo: apiRouteOperation({
    method: 'POST',
    // Optional OpenAPI operation documentation.
    openApiOperation: {
      tags: ['example-api', 'todos', 'pages-router']
    }
  })
    // Input schema for strictly-typed request, request validation and OpenAPI documentation.
    .input({
      contentType: 'application/json',
      body: z.object({
        name: z.string()
      })
    })
    // Output schema for strictly-typed responses and OpenAPI documentation.
    .outputs([
      {
        status: 201,
        contentType: 'application/json',
        schema: z.string()
      },
      {
        status: 401,
        contentType: 'application/json',
        schema: z.string()
      }
    ])
    // Optional middleware logic executed before request validation.
    .middleware((req, res) => {
      if (!req.headers.authorization) {
        res.status(401).json('Unauthorized'); // Type-checked response.
      }
    })
    .handler((req, res) => {
      const { name } = req.body; // Strictly-typed request.
      res.status(201).json(`New TODO created: ${name}`); // Type-checked response.
    })
});

All of above type-safe endpoints will be now auto-generated to your OpenAPI spec and exposed in the documentation:

Client

To achieve end-to-end type-safety, you can use any client implementation that relies on the generated OpenAPI specification, e.g. openapi-client-axios.

RPC

You can also define your APIs with RPC route handlers that also auto-generate the OpenAPI spec. The RPC endpoints can be consumed with the type-safe API client for end-to-end type safety.

App Router:

// src/app/api/rpc/route.ts

import { rpcOperation, rpcRoute } from 'next-rest-framework';
import { z } from 'zod';

const TODOS = [
  {
    id: 1,
    name: 'TODO 1',
    completed: false
  }
];

const todoSchema = z.object({
  id: z.number(),
  name: z.string(),
  completed: z.boolean()
});

// Example App Router RPC handler.
const { POST, client } = rpcRoute({
  getTodos: rpcOperation()
    // Output schema for strictly-typed responses and OpenAPI documentation.
    .outputs([
      {
        schema: z.array(todoSchema)
      }
    ])
    .handler(() => {
      // Type-checked response.
      return TODOS;
    }),

  getTodoById: rpcOperation()
    .input(z.string())
    .outputs([
      {
        schema: z.object({
          error: z.string()
        })
      },
      {
        schema: todoSchema
      }
    ])
    .handler((id) => {
      const todo = TODOS.find((t) => t.id === Number(id));

      if (!todo) {
        // Type-checked response.
        return { error: 'TODO not found.' };
      }

      // Type-checked response.
      return todo;
    }),

  createTodo: rpcOperation()
    // Input schema for strictly-typed request, request validation and OpenAPI documentation.
    .input(
      z.object({
        name: z.string()
      })
    )
    // Output schema for strictly-typed responses and OpenAPI documentation.
    .outputs([{ schema: todoSchema }])
    .handler(async ({ name: _name }) => {
      // Create todo.
      const todo = { id: 2, name: _name, completed: false };

      // Type-checked response.
      return todo;
    }),

  deleteTodo: rpcOperation()
    .input(z.string())
    .outputs([
      { schema: z.object({ error: z.string() }) },
      { schema: z.object({ message: z.string() }) }
    ])
    .handler((id) => {
      // Delete todo.
      const todo = TODOS.find((t) => t.id === Number(id));

      if (!todo) {
        // Type-checked response.
        return {
          error: 'TODO not found.'
        };
      }

      // Type-checked response.
      return { message: 'TODO deleted.' };
    })
});

export { POST };

export type AppRouterRpcClient = typeof client;

Pages Router:

// src/pages/api/rpc.ts

import { rpcApiRoute } from 'next-rest-framework';

// Example Pages Router RPC handler.
const handler = rpcApiRoute({
  // ...
  // Exactly the same as the App Router example.
});

export default handler;

export type RpcClient = typeof handler.client;

The RPC routes will also be included in your OpenAPI spec now. Note that the rpcOperation definitions can be also be placed outside the rpcRouteHandler if you do not want to expose them as public APIs as long as they're called server-side.

Client

The strongly-typed RPC operations can be called inside inside React server components and server actions like any functions:

'use server';

import { client } from 'app/api/rpc/route';

export default async function Page() {
  const todos = await client.getTodos();

  const createTodo = async (name: string) => {
    'use server';
    return client.createTodo({ name });
  };

  // ...
}

For client-rendered components you can use the strongly-typed rpcClient or use server actions from the above example:

'use client';

import { useState } from 'react';
import { rpcClient } from 'next-rest-framework/rpc-client';
import { type RpcClient } from 'app/api/rpc/route';

const client = rpcClient<RpcClient>({
  url: 'http://localhost:3000/api/rpc'
});

export default function Page() {
  // ...

  useEffect(() => {
    client
      .getTodos()
      .then(() => {
        // ...
      })
      .catch(console.error);
  }, []);

  const createTodo = async (name: string) => {
    'use server';
    return client.createTodo({ name });
  };

  // ...
}

The rpcClient calls can also be easily integrated with any data fetching framework, like React Query or RTKQ.

API reference

Docs handler options

The following options can be passed to the docsRouteHandler (App Router) and docsApiRouteHandler (Pages Router) functions for customizing Next REST Framework:

Name	Description
`deniedPaths`	Array of paths that are denied by Next REST Framework and not included in the OpenAPI spec. Supports wildcards using asterisk `` and double asterisk `` for recursive matching. Example: `['/api/disallowed-path', '/api/disallowed-path-2/', '/api/disallowed-path-3/**']` Defaults to no paths being disallowed.
`allowedPaths`	Array of paths that are allowed by Next REST Framework and included in the OpenAPI spec. Supports wildcards using asterisk `` and double asterisk `` for recursive matching. Example: `['/api/allowed-path', '/api/allowed-path-2/', '/api/allowed-path-3/**']` Defaults to all paths being allowed.
`openApiObject`	An OpenAPI Object that can be used to override and extend the auto-generated specification.
`openApiJsonPath`	Path that will be used for fetching the OpenAPI spec - defaults to `/openapi.json`. This path also determines the path where this file will be generated inside the `public` folder.
`autoGenerateOpenApiSpec`	Setting this to `false` will not automatically update the generated OpenAPI spec when calling the docs handler endpoints. Defaults to `true`.
`docsConfig`	A Docs config object for customizing the generated docs.
`suppressInfo`	Setting this to `true` will suppress all informational logs from Next REST Framework. Defaults to `false`.

Docs config

The docs config options can be used to customize the generated docs:

Name	Description
`provider`	Determines whether to render the docs using Redoc (`redoc`) or SwaggerUI `swagger-ui`. Defaults to `redoc`.
`title`	Custom title, used for the visible title and HTML title.
`description`	Custom description, used for the visible description and HTML meta description.
`faviconUrl`	Custom HTML meta favicon URL.
`logoUrl`	A URL for a custom logo.

REST

Route handler options

The following options cam be passed to the routeHandler (App Router) and apiRouteHandler (Pages Router) functions to create new API endpoints:

Name	Description	Required
`GET \| PUT \| POST \| DELETE \| OPTIONS \| HEAD \| PATCH`	A Method handler object.	`true`
`openApiPath`	An OpenAPI Path Item Object that can be used to override and extend the auto-generated specification.	`false`

Route operations

The route operation functions routeOperation (App Router) and apiRouteOperation (Pages Router) allow you to define your API handlers for your endpoints. These functions accept an OpenAPI Operation object as a parameter, that can be used to override the auto-generated specification. Calling this function allows you to chain your API handler logic with the following functions.

Name	Description
`input`	A Route operation input function for defining the validation and documentation of the request.
`outputs`	An Route operation outputs function for defining the validation and documentation of the response.
`handler`	A Route operation-handler function for defining your business logic.
`middleware`	A Route operation middleware function that gets executed before the request input is validated.

Route operation input

The route operation input function is used for type-checking, validation and documentation of the request, taking in an object with the following properties:

Name	Description	Required
`contentType`	The content type header of the request. When the content type is defined, a request with an incorrect content type header will get an error response.	`false`
`body`	A Zod schema describing the format of the request body. When the body schema is defined, a request with an invalid request body will get an error response.	`false`
`query`	A Zod schema describing the format of the query parameters. When the query schema is defined, a request with invalid query parameters will get an error response.	`false`

Calling the route operation input function allows you to chain your API handler logic with the Route operation outputs, Route operation middleware and Route operation handler functions.

Route operation outputs

The route operation outputs function is used for type-checking and documentation of the response, taking in an array of objects with the following properties:

Name	Description	Required
`status`	A status code that your API can return.	`true`
`contentType`	The content type header of the response.	`true`
`schema`	A Zod schema describing the format of the response data.	`true`

Calling the route operation outputs function allows you to chain your API handler logic with the Route operation middleware and Route operation handler functions.

Route operation middleware

The route operation middleware function is executed before validating the request input. The function takes in the same parameters as the Next.js Route Handlers and API Routes handlers.

Calling the route operation middleware function allows you to chain your API handler logic with the Handler function.

Route operation handler

The route operation handler function is a strongly-typed function to implement the business logic for your API. The function takes in strongly-typed versions of the same parameters as the Next.js Route Handlers and API Routes handlers.

RPC

RPC route handler options

The rpcRouteHandler (App Router) and rpcApiRouteHandler (Pages Router) functions allow the following options as the second parameter after passing your RPC operations.

Name	Description	Required
`openApiPath`	An OpenAPI Path Item Object that can be used to override and extend the auto-generated specification.	`false`
`openApiOperation`	An OpenAPI Path Item Object that can be used to override and extend the auto-generated specification.	`false`

RPC operations

The rpcOperation function allows you to define your API handlers for your RPC endpoint. Calling this function allows you to chain your API handler logic with the following functions.

Name	Description
`input`	An RPC operation input function for defining the validation and documentation of the operation.
`outputs`	An RPC operation outputs function for defining the validation and documentation of the response.
`handler`	An RPC operation handler function for defining your business logic.
`middleware`	An RPC operation middleware function that gets executed before the operation input is validated.

RPC operation input

The RPC operation input function is used for type-checking, validation and documentation of the RPC call. It takes in a A Zod schema as a parameter that describes the format of the operation input. When the input schema is defined, an RPC call with invalid input will get an error response.

Calling the RPC input function allows you to chain your API handler logic with the RPC operation outputs, RPC middleware and RPC handler functions.

RPC operation outputs

The RPC operation outputs function is used for type-checking and documentation of the response, taking in an array of objects with the following properties:

Name	Description	Required
`schema`	A Zod schema describing the format of the response data.	`true`
`name`	An optional name used in the generated OpenAPI spec, e.g. `GetTodosErrorResponse`.	`false`

Calling the RPC operation outputs function allows you to chain your API handler logic with the RPC operation middleware and RPC operation handler functions.

npx next-rest-framework generate to generate the openapi.json file.
npx next-rest-framework validate to validate that the openapi.json file is up-to-date.

The next-rest-framework validate command is useful to have as part of the static checks in your CI/CD pipeline. Both commands support the following options:

Name	Description
`--skipBuild <boolean>`	By default, `next build` is used to build your routes. If you have already created the build, you can skip this step by setting this to `true`.
`--distDir <string>`	Path to your production build directory. Defaults to `.next`.
`--timeout <string>`	The timeout for generating the OpenAPI spec. Defaults to 60 seconds.
`--configPath <string>`	In case you have multiple docs handlers with different configurations, you can specify which configuration you want to use by providing the path to the API. Example: `/api/my-configuration`.
`--debug <boolean>`	Inherit and display logs from the `next build` command. Defaults to `false`.

Next REST Framework

Table of contents

Lightweight, type-safe, easy to use

App Router:

Pages Router:

REST

App Router:

Pages Router:

Client

App Router:

Pages Router:

Client

REST

RPC

About

Languages