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Type-safe HTML templating language for Go with compile-time safety
Elysia is a Bun-first TypeScript web framework with end-to-end type safety, sub-millisecond cold starts and Eden Treaty for typed clients with zero codegen. We rate it 86/100 — the best backend framework for Bun in 2026.
Elysia is a Bun-first TypeScript web framework that pairs an Express-like chainable API with end-to-end type safety, TypeBox validation and a JIT-compiled router that benchmarks at over 2.5 million requests per second. We rate it 86/100 — if your team has already committed to Bun (or is willing to), Elysia is the most ergonomic, type-safe and fastest backend framework available in 2026, with the only meaningful trade-off being a smaller community than Hono.
Elysia is an open-source TypeScript web framework created by SaltyAom and first released on . It is purpose-built around Bun's runtime APIs — using Bun's HTTP server, file system primitives and hot reload directly — and it ships under the MIT license on GitHub at elysiajs/elysia, where it has crossed 18,200+ stars as of with the most recent release being v1.4.28.
The pitch is straightforward: most TypeScript backend frameworks force you to choose between speed (Fastify, raw Bun.serve), portability (Hono runs everywhere), or developer experience (Nest, tRPC). Elysia argues you do not have to choose. Its chainable API derives compile-time types from runtime schemas using TypeBox, then exposes those types to your client through Eden Treaty — giving you Express-style routing with the safety of tRPC and benchmark numbers that beat both. It is also the framework Bun itself recommends in its official ecosystem docs.
t namespace exposes JSON-schema-compliant validators for body, query, params, headers and response. Schemas double as runtime guards and TypeScript types — one source of truth.@elysiajs/openapi plugin generates a complete OpenAPI 3.1 document and Swagger UI from your route definitions automatically — no decorators, no extra annotations.onStart, onRequest, onParse, derive, onError, etc.) and user-defined macros make it possible to encapsulate cross-cutting concerns without the middleware-stack ergonomics tax.@elysiajs/node adapter lets you run the same Elysia code on Node.js if you cannot ship Bun in production, at a roughly 30–40% performance cost compared to native Bun.Sentiment is unusually warm for a backend framework, especially among developers migrating from Express. On Dev.to, the most-read switchover post praises Elysia for "less boilerplate, cleaner code, and direct response returns instead of req/res/next" — a recurring theme. On Reddit's r/node and r/bun, the most upvoted threads highlight Eden Treaty as the killer feature: several developers describe it as "tRPC without the codegen step" and the closest thing TypeScript has to a Phoenix LiveView equivalent for type safety between client and server.
The recurring complaints are honest and worth weighing. The biggest one is the Bun lock-in: every comparison piece in 2026 — from Encore's Elysia-vs-Hono breakdown to PkgPulse's framework roundups — flags that Hono's portability across Node, Deno, Cloudflare Workers and AWS Lambda still makes it the safer multi-runtime pick. Hono's GitHub star count (~90k) is roughly 5× Elysia's, which means more StackOverflow answers, more community plugins and more tutorials when something goes wrong. A separate critique on Dev.to from a long-time user notes that Elysia's documentation is "friendly for newbies but lacks the depth a seasoned developer might crave," especially around plugin internals and advanced macro patterns.
Elysia is fully open source under the MIT license. There is no paid tier, no usage cap, no enterprise upsell and no telemetry collected by the project. You self-host on Bun (or on Node.js via the official adapter) on any provider you like.
| Plan | Price | Key Limits |
|---|---|---|
| Open Source (only tier) | $0 forever | Unlimited routes, requests, deployments. MIT license. Community support via Discord and GitHub Issues. Pay only your own infrastructure. |
For comparison, equivalent typed-API stacks on managed runtimes (e.g., Vercel Functions + tRPC at scale, or Encore Cloud's hosted tier) start in the tens of dollars per month and scale into hundreds. Elysia + Bun on a $5 Hetzner box can comfortably handle most early-stage SaaS workloads.
Best for: Backend engineers and full-stack TypeScript teams who have already adopted Bun (or are greenfield enough to adopt it), small-to-mid SaaS teams who want one source of truth between server and client without a separate tRPC or OpenAPI codegen step, and performance-sensitive APIs (real-time, edge-adjacent, high-RPS endpoints) where every millisecond of framework overhead matters.
Not ideal for: Teams locked into Node.js LTS for compliance reasons, multi-runtime projects that need to deploy the same codebase to Cloudflare Workers, Deno Deploy and AWS Lambda (Hono is the better pick here), or large enterprise teams that prioritize community size, vendor support and the volume of available StackOverflow answers over raw DX.
Pros:
Cons:
The two closest alternatives are Hono — broader runtime support across Node, Bun, Deno, Cloudflare Workers and AWS Lambda, with a much larger community but slightly less ergonomic type inference — and Encore, which adds infrastructure-as-code and a managed cloud control plane on top of a typed API surface. tRPC remains the dominant choice for Next.js teams who want typed RPC without changing backend frameworks. For raw Bun performance with no framework at all, the standard Bun.serve is always an option.
Yes, with a clear caveat. If you have already committed to Bun, or you are starting a greenfield TypeScript backend in 2026, Elysia is the framework we would reach for first. The combination of Eden Treaty's typed client, TypeBox-driven validation, automatic OpenAPI, and Bun-native performance is unmatched in the current ecosystem and is the closest TypeScript has come to a Phoenix-like full-stack typed experience. The 86/100 rating reflects two real deductions: Bun lock-in (which limits its addressable market today) and a community still growing into Hono's footprint. For teams unwilling to bet on Bun, Hono remains the safer multi-runtime pick. For everyone else, Elysia is genuinely a joy to ship with.
@elysiajs/node adapter also lets you run the same code on Node.js, and integrations exist for Vercel, Netlify and Cloudflare Workers.
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