TypeSpec

Design APIs

Design your data up front and generate schemas, API specifications, client / server code, docs, and more.

import "@typespec/http";

using Http;

model Store {
  name: string;
  address: Address;
}

model Address {
  street: string;
  city: string;
}

@route("/stores")
interface Stores {
  list(@query filter: string): Store[];
  read(@path id: Store): Store;
}

openapi: 3.0.0
info:
  title: (title)
  version: 0.0.0
tags: []
paths:
  /stores:
    get:
      operationId: Stores_list
      parameters:
        - name: filter
          in: query
          required: true
          schema:
            type: string
      responses:
        '200':
          description: The request has succeeded.
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/Store'
  /stores/{id}:
    get:
      operationId: Stores_read
      parameters:
        - name: id
          in: path
          required: true
          schema:
            $ref: '#/components/schemas/Store'
      responses:
        '200':
          description: The request has succeeded.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Store'
components:
  schemas:
    Address:
      type: object
      required:
        - street
        - city
      properties:
        street:
          type: string
        city:
          type: string
    Store:
      type: object
      required:
        - name
        - address
      properties:
        name:
          type: string
        address:
          $ref: '#/components/schemas/Address'

import "@typespec/json-schema";

using JsonSchema;

@jsonSchema
namespace Schemas;

model Person {
  name: string;
  address: Address;
  @uniqueItems nickNames?: string[];
  cars?: Car[];
}

model Address {
  street: string;
  city: string;
  country: string;
}

model Car {
  kind: "ev" | "ice";
  brand: string;
  @minValue(1900) year: int32;
}

$schema: https://json-schema.org/draft/2020-12/schema
$id: schema.yaml
$defs:
  Address:
    $schema: https://json-schema.org/draft/2020-12/schema
    $id: Address
    type: object
    properties:
      street:
        type: string
      city:
        type: string
      country:
        type: string
    required:
      - street
      - city
      - country
  Car:
    $schema: https://json-schema.org/draft/2020-12/schema
    $id: Car
    type: object
    properties:
      kind:
        anyOf:
          - type: string
            const: ev
          - type: string
            const: ice
      brand:
        type: string
      year:
        type: integer
        minimum: 1900
        maximum: 2147483647
    required:
      - kind
      - brand
      - year
  Person:
    $schema: https://json-schema.org/draft/2020-12/schema
    $id: Person
    type: object
    properties:
      name:
        type: string
      address:
        $ref: Address
      nickNames:
        type: array
        items:
          type: string
        uniqueItems: true
      cars:
        type: array
        items:
          $ref: Car
    required:
      - name
      - address

import "@typespec/protobuf";

using Protobuf;

@package({
  name: "addressbook",
})
namespace AddressBook;

enum PhoneType {
  MOBILE: 0,
  HOME: 1,
  WORK: 2,
}

model PhoneNumber {
  @field(1) number: string;
  @field(2) type: PhoneType;
}

model Person {
  @field(1) name: string;
  @field(2) id: int32;
  @field(3) email: string;
  @field(4) phones: PhoneNumber[];
  @field(5) last_updated: WellKnown.Timestamp;
}

// Generated by Microsoft TypeSpec

syntax = "proto3";

package addressbook;

import "google/protobuf/timestamp.proto";

enum PhoneType {
  MOBILE = 0;
  HOME = 1;
  WORK = 2;
}

message PhoneNumber {
  string number = 1;
  PhoneType type = 2;
}

message Person {
  string name = 1;
  int32 id = 2;
  string email = 3;
  repeated PhoneNumber phones = 4;
  google.protobuf.Timestamp last_updated = 5;
}

Why TypeSpec

API-First for developers

With TypeSpec, remove the handwritten files that slow you down, and generate standards-compliant API schemas in seconds.

Lightweight language for defining APIs

Inspired by TypeScript, TypeSpec is a minimal language that helps developers describe API shapes in a familiar way.

Learn more →

Easy integration with your toolchain

Write TypeSpec, emit to various formats and integrate with their ecosystems.

Multi-protocol support

TypeSpec's standard library includes support for OpenAPI 3.0, JSON Schema 2020-12 and Protobuf.

Learn more →

~ /my-project tsp init
 
? Select a template    Empty project
>   REST API

Productivity

Streamline your OpenAPI workflow

Benefit from a huge ecosystem of OpenAPI tools for configuring API gateways, generating code, and validating your data.

Generate OpenAPI from TypeSpec

Learn more →

main.tsp
openapi.yaml

import "@typespec/http";

using Http;

model Pet {
  name: string;
  age: int32;
}

model Store {
  name: string;
  address: Address;
}

model Address {
  street: string;
  city: string;
}

@route("/pets")
interface Pets {
  list(@query filter: string): Pet[];
  create(@body pet: Pet): Pet;
  read(@path id: string): Pet;
}

@route("/stores")
interface Stores {
  list(@query filter: string): Store[];
  read(@path id: string): Store;
}

openapi: 3.0.0
info:
  title: (title)
  version: 0.0.0
tags: []
paths:
  /pets:
    get:
      operationId: Pets_list
      parameters:
        - name: filter
          in: query
          required: true
          schema:
            type: string
      responses:
        '200':
          description: The request has succeeded.
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/Pet'
    post:
      operationId: Pets_create
      parameters: []
      responses:
        '200':
          description: The request has succeeded.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Pet'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/Pet'
  /pets/{id}:
    get:
      operationId: Pets_read
      parameters:
        - name: id
          in: path
          required: true
          schema:
            type: string
      responses:
        '200':
          description: The request has succeeded.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Pet'
  /stores:
    get:
      operationId: Stores_list
      parameters:
        - name: filter
          in: query
          required: true
          schema:
            type: string
      responses:
        '200':
          description: The request has succeeded.
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/Store'
  /stores/{id}:
    get:
      operationId: Stores_read
      parameters:
        - name: id
          in: path
          required: true
          schema:
            type: string
      responses:
        '200':
          description: The request has succeeded.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Store'
components:
  schemas:
    Address:
      type: object
      required:
        - street
        - city
      properties:
        street:
          type: string
        city:
          type: string
    Pet:
      type: object
      required:
        - name
        - age
      properties:
        name:
          type: string
        age:
          type: integer
          format: int32
    Store:
      type: object
      required:
        - name
        - address
      properties:
        name:
          type: string
        address:
          $ref: '#/components/schemas/Address'

Ecosystem

Ensure data consistency

Define common models to use across your APIs, use the JSON schema emitter to get the JSON schema for your types and use them to validate your data.

JSON schema emitter reference

Learn more →

main.tsp
common.tsp

import "./common.tsp";

namespace MyOrg.Accounts;

using MyOrg.Types;

model Account {
  id: id;
  firstName: string;
  lastName: string;
  createdAt: utcDateTime;

  // Use imported type by name only when using `using`
  ssn: ssn;

  // Or use the fully qualified name
  email: MyOrg.Types.email;

  balance: Amount;
}

model Amount {
  value: decimal128;
  currency: Currency;
}

// Create your own error types by extending the Error type
model AccountError is Error<"duplicate-account" | "invalid-account">;

op createAccount(account: Account): Account;

op charge(accountId: id, amount: Amount): void | AccountError;

namespace MyOrg.Types;

@format("uuid")
scalar uuid extends string;

// Defined a standard id type that all models can use
scalar id extends uuid;

@pattern(".+\\@.+\\..+")
scalar email extends string;

@pattern("^\\d{3}-\\d{2}-\\d{4}$")
scalar ssn extends string;

/**
 * Standard error response
 */
model Error<T extends string> {
  code: T;
  message: string;
  details?: Record<string>;
  timestamp: utcDateTime;
}

enum Currency {
  USD,
  EUR,
  GBP,
  CAD,
  JPY,
}

Tooling

Full language support in VS Code and Visual Studio

TypeSpec provides built-in support for many common editor features such as syntax highlighting, code completion, and more.

Check out our available tooling

Learn more →

Extensibility

Generate assets in many formats

TypeSpec is built around extensibility - you can write your own emitter or add custom metadata using a new decorator.

Getting started with writing a library

Learn more →

extern dec group(target: TypeSpec.Reflection.Model, name: valueof string);

import { DecoratorContext, EmitContext, Model, resolvePath } from "@typespec/compiler";

export async function $onEmit(context: EmitContext) {
  const outputDir = resolvePath(context.emitterOutputDir, "hello.txt");
  await context.program.host.writeFile(outputDir, "hello world!");
}

const groupKey = Symbol.for("my-library/group");
export function $group(context: DecoratorContext, target: Model, value: string) {
  context.program.stateMap(groupKey).set(target, value);
}

Start your TypeSpec journey

Install the TypeSpec CLI or check out the playground to get started.

Get Started Try it out

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	13
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