Our Principle

Design for Humans

Our goal is to design an ergonomic, sensible, and productive framework that even beginners can use easily

Designed to avoid unnecessary complexity and type complexity for you to focus on building

A framework that feels just like JavaScript

typescript

import { Elysia, file } from 'elysia'

new Elysia()
	.get('/', 'Hello World')
	.get('/image', file('mika.webp'))
	.get('/stream', function* () {
		yield 'Hello'
		yield 'World'
	})
	.ws('/realtime', {
		message(ws, message) {
			ws.send('got:' + message)
		}
	})
	.listen(3000)

21x

faster than Express

6x

faster than Fastify

Elysia Bun
2,454,631 reqs/s
Gin Go
676,019
Spring Java
506,087
Fastify Node
415,600
Express Node
113,117
Nest Node
105,064

Measured in requests/second. Result from TechEmpower Benchmark Round 22 (2023-10-17) in PlainText

Your code, Your Runtime

Elysia is optimized for Bun,

but not vendor lock-in to Bun

Elysia is built on Web-Standard

allowing you to run Elysia anywhere

Best in Class Type Safety

Bring your own Validator

With support for Standard Schema

Elysia offers a robust built-in validation, but you can also bring your favorite validator, like Zod, Valibot, ArkType, Effect , and more

With seamless support for type inference, and OpenAPI. You will feel right at home.

import { Elysia
, t
 } from 'elysia'


new Elysia
()
	// Try hover body  ↓
	.post
('/user', ({ body
 }) => body
, {
		body
: t
.Object
({
			name
: t
.Literal
('SaltyAom'),
			age
: t
.Number
(),
			friends
: t
.Array
(t
.String
())
		})
	})

import { Elysia
 } from 'elysia'
import { z
 } from 'zod'

new Elysia
()
	// Try hover body  ↓
	.post
('/user', ({ body
 }) => body
, {
		body
: z
.object
({
			name
: z
.literal
('SaltyAom'),
			age
: z
.number
(),
			friends
: z
.array
(z
.string
())
		})
	})

import { Elysia
 } from 'elysia'
import * as v
 from 'valibot'

new Elysia
()
	// Try hover body  ↓
	.post
('/user', ({ body
 }) => body
, {
		body
: v
.object
({
			name
: v
.literal
('SaltyAom'),
			age
: v
.number
(),
			friends
: v
.array
(v
.string
())
		})
	})

import { Elysia
 } from 'elysia'
import { type
 } from 'arktype'

new Elysia
()
	// Try hover body  ↓
	.post
('/user', ({ body
 }) => body
, {
		body
: type
({
			name
: '"Elysia"',
			age
: 'number',
			friends
: 'string[]'
		})
	})

import { Elysia
 } from 'elysia'
import { Schema
 } from 'effect'

new Elysia
()
	// Try hover body  ↓
	.post
('/user', ({ body
 }) => body
, {
		body
: Schema
.standardSchemaV1
(
			Schema
.Struct
({
				name
: Schema
.Literal
('Elysia'),
				age
: Schema
.Number
,
				friends
: Schema
.Array
(Schema
.String
)
			})
		)
	})

Say hello to your actual API with OpenAPI

We take OpenAPI documentation seriously

With deep integration with OpenAPI schema
Elysia can generate API documentation out of the box

Elysia deeply integrates with OpenAPI to generate beautiful API documentation out of the box
With Elysia OpenAPI Type Gen, Elysia uses TypeScript types and turns them into OpenAPI schema automatically
You can try out the API directly from the API documentation
Describe your API with a built-in schema, or bring your own validator that supports OpenAPI documents
Model is seamlessly supported out of the box, and integrated with runtime to ensure accuracy

Item 1 of 5

OpenAPI features, all in 1 line

Just 1 line of code, you get a full-fledged API documentation effortlessly

And with OpenAPI Type Gen, Elysia can turn TypeScript types into an API documentation (like FastAPI but from TypeScript types)

OpenAPIWith Type Gen

typescript

import { Elysia } from 'elysia'
import { openapi } from '@elysiajs/openapi'

new Elysia()
	.use(openapi())
	.listen(3000)

typescript

import { Elysia } from 'elysia'
import { openapi, fromTypes } from '@elysiajs/openapi'

export const app = new Elysia()
	.use(
		openapi({
			references: fromTypes()
		})
	)

11.88ms

POST /character/:id/chat

Playback

Request

Validation

Transaction

Upload

Sync

For DevOps

OpenTelemetry

Elysia has 1st party support for OpenTelemetry. Instrumentation is built-in, so you can easily monitor your services regardless of the platform.

typescript

import { treaty
 } from '@elysiajs/eden'
import type { App
 } from './server'

const api
 = treaty
<App
>('api.elysiajs.com')

const { data
 } = await api
.profile
.patch
({
    age
: 21
})

For Frontend

End-to-end Type Safety

Like tRPC, Elysia provides type-safety from the backend to the frontend without code generation. The interaction between frontend and backend is both type-checked at compile and runtime.

Test with Confidence

Type safe with auto-completion

Elysia provides a type-safe layer to interact with and test your server, from routes to parameters.

With auto-completion, you can easily write tests for the server without any hassle.

typescript

import { treaty
 } from '@elysiajs/eden'
import { app
 } from './index'
import { test
, expect
 } from 'bun:test'

const server
 = treaty
(app
)

test
('should handle duplicated user', async () => {
	const { error
 } = await server
.user
.put
({Argument of type '{ username: string; }' is not assignable to parameter of type '{ username: string; password: string; }'.
  Property 'password' is missing in type '{ username: string; }' but required in type '{ username: string; password: string; }'.
	    username
: 'mika',
	})

	expect
(error
?.value
).toEqual
({
		success
: false,
		message
: 'Username already taken'
	})
})

What people say about

Elysia

Aqueel

@AqueelMiq

Jetfuel on bun at X! @shlomiatar who built the framework has an eye for picking the right tools for the job.

Shlomi Atar

@shlomiatar

also a shoutout to @saltyAom and the phenomenal Elysia js that is powering our server driven UI. Incredible work.

htmx.org

@htmx_org

htmx works great w/ @bunjavascript, @elysiaJS and @tursodatabase btw

Marc Laventure

@MarcLaventure

both engineering+monetary contributions are paramount for OSS we proudly sponsor dozens of projects: @elysiaJS @LitestarAPI @honojs @daveshanley @kevin_jahns @MarijnJH & help maintain repos+contribute to OSS at blistering cadence. it's @scalar's ethos to be a catalyst for OSS

Jarred Sumner

@jarredsumner

You can use Express with Bun, but often we see people using Elysia, Hono, or Bun.serve() directly.

Runyasak Ch. 💚

@runyasak

Started using @elysiaJS to create a Discord Bot and found the type system beautifully easy. DX is fantastic and coding is fun! Use @DrizzleORM with PostgreSQL. So much easier than I've used before. ElysiaJS has proved to me that great performance and DX can live together. 😎

Herrington Darkholme

@hd_nvim

Was introduced to @elysiaJS today and it looks pretty solid. end-to-end type safety/guard/swapper are killer features of the modern web! (and it's fast)

scalar.com

@scalar

so excited to be part of the amazing @elysiaJS community!

José Donato 🦋

@josedonato__

handling tables with ~350k rows like it's nothing. Working on allowing @ag_grid server side row model when connecting a custom backend to @openbb_finance Terminal Pro. Backend in @elysiaJS + @bunjsproject.

Bewinxed

@Bewinxed

Elysia single handedly carrying js backends I have been using it almost exclusively for all my projects

MikroORM

@MikroORM

I've been playing a bit with @bunjavascript and @elysiaJS, need to do a few more tweaks before the release, but next version should work more natively with bun when it comes to TS support detection, e.g. the CLI works without ts-node installed.

Because of You

Elysia is not owned by an organization, driven by volunteers, and community. Elysia is possible by these awesome sponsors.

Gold Sponsors 💛

Silver Sponsors 🤍

Generous Sponsors 💞

Individual Sponsors 💕

Thank you for making Elysia possible

We can only develop Elysia full-time thanks to your support.

With love from our community

Got more questions?

Just Ask!

Can I use Zod with Elysia?

Elysia validates incoming request data (params, query, body, headers, cookies, response) before your handler runs.

It ships with a built‑in schema builder (Elysia.t) based on TypeBox, but it also natively supports any “Standard Schema” library – that includes Zod, Valibot, Yup, Joi, ArkType, Effect‑Schema, and many more.

The first production ready, and most loved Bun framework

Trusted by team at

Elysia Bun

Gin Go

Spring Java

Fastify Node

Express Node

Nest Node

Your code, Your Runtime

Elysia is optimized for Bun,

but not vendor lock-in to Bun

Elysia is built on Web-Standard

allowing you to run Elysia anywhere

Best in Class Type Safety

OpenAPI features, all in 1 line

What people say about

Because of You

San Francisco Compute Company

Bun

Scalar

CodeRabbit

Better Auth

Comp AI

Jarred Sumner

Phoomparin Mano

Got more questions?

The first production ready,
and most loved Bun framework