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)

Bring your own Validator

With support for Standard Schema

Elysia offers a robust built-in validation, but you can also bring your favorite validator, lik Zod, Valibot, ArkType, Effect , etc.

With seamless support for type inference, and OpenAPI. You will feels 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
)
			})
		)
	})

Best in Class Type Safety

Your own documentation in 1 line

It's not magic

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

Scalar documentation generated by Elysia using Elysia OpenAPI plugin

typescript

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

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

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 on 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 on compile and runtime.

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

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 says 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.