name: encore-api
description: Create type-safe API endpoints with Encore.ts.

Encore API Endpoints

Instructions

When creating API endpoints with Encore.ts, follow these patterns:

1. Import the API module

import { api } from "encore.dev/api";

2. Define typed request/response interfaces

Always define explicit TypeScript interfaces for request and response types:

interface CreateUserRequest {
  email: string;
  name: string;
}

interface CreateUserResponse {
  id: string;
  email: string;
  name: string;
}

3. Create the endpoint

export const createUser = api(
  { method: "POST", path: "/users", expose: true },
  async (req: CreateUserRequest): Promise<CreateUserResponse> => {
    // Implementation
  }
);

API Options

Parameter Types

Path Parameters

// Path: "/users/:id"
interface GetUserRequest {
  id: string;  // Automatically mapped from :id
}

Query Parameters

import { Query } from "encore.dev/api";

interface ListUsersRequest {
  limit?: Query<number>;
  offset?: Query<number>;
}

Headers

import { Header } from "encore.dev/api";

interface WebhookRequest {
  signature: Header<"X-Webhook-Signature">;
  payload: string;
}

Request Validation

Encore validates requests at runtime using TypeScript types. Add constraints for stricter validation:

import { api, Min, Max, MinLen, MaxLen, IsEmail, IsURL } from "encore.dev/api";

interface CreateUserRequest {
  email: string & IsEmail;                    // Must be valid email
  username: string & MinLen<3> & MaxLen<20>;  // 3-20 characters
  age: number & Min<13> & Max<120>;           // Between 13 and 120
  website?: string & IsURL;                   // Optional, must be URL if provided
}

Available Validators

Validation Error Response

Invalid requests return 400 with details:

{
  "code": "invalid_argument",
  "message": "validation failed",
  "details": { "field": "email", "error": "must be a valid email" }
}

Raw Endpoints

Use api.raw for webhooks or when you need direct request/response access:

export const stripeWebhook = api.raw(
  { expose: true, path: "/webhooks/stripe", method: "POST" },
  async (req, res) => {
    const sig = req.headers["stripe-signature"];
    // Handle raw request...
    res.writeHead(200);
    res.end();
  }
);

Error Handling

Use APIError for proper HTTP error responses:

import { APIError, ErrCode } from "encore.dev/api";

// Throw with error code
throw new APIError(ErrCode.NotFound, "user not found");

// Or use shorthand
throw APIError.notFound("user not found");
throw APIError.invalidArgument("email is required");
throw APIError.unauthenticated("invalid token");

Common Error Codes

Static Assets

Serve static files (HTML, CSS, JS, images) with api.static:

import { api } from "encore.dev/api";

// Serve files from ./assets under /static/*
export const assets = api.static(
  { expose: true, path: "/static/*path", dir: "./assets" }
);

// Serve at root (use !path for fallback routing)
export const frontend = api.static(
  { expose: true, path: "/!path", dir: "./dist" }
);

// Custom 404 page
export const app = api.static(
  { expose: true, path: "/!path", dir: "./public", notFound: "./404.html" }
);

Guidelines

• Always use import not require
• Define explicit interfaces for type safety
• Use expose: true only for public endpoints
• Use api.raw for webhooks, api for everything else
• Throw APIError instead of returning error objects
• Path parameters are automatically extracted from the path pattern
• Use validation constraints (Min, MaxLen, etc.) for user input