ElysiaJS

Ergonomic web framework for JavaScript and TypeScript with end-to-end type safety and strong developer experience. Built on web standards, it runs on Bun, Node.js, Cloudflare Workers, and other runtimes without vendor lock-in.

Production-ready and favored by teams building server-driven UIs, APIs, and real-time apps. Differentiates from Express and Fastify through inferred types that flow from server to client via Eden Treaty, OpenAPI generation directly from TypeScript code without annotations, and a plugin architecture that composes cleanly. Integrates with htmx, Prisma, Drizzle, and the broader Bun ecosystem.

Key capabilities:

• End-to-end type safety with Eden Treaty for typed API clients
• OpenAPI spec generation from TypeScript, no manual annotations or CLI
• Validation via TypeBox, Zod, Valibot, ArkType, or Effect Schema
• Built-in file handling, streaming responses, and WebSocket support
• Composable plugins and macros for auth, validation, and cross-cutting logic

Common adoption: REST and RPC APIs, real-time backends for Discord bots or chat, server-driven UIs with htmx, high-throughput data pipelines. Developers appreciate instant hot reload with Bun, runtime-agnostic design, and refactoring confidence from compile-time type checking.