# Celeris

> Celeris is a high-performance HTTP engine for Go. It replaces the standard net/http server with its own asynchronous I/O core — io_uring or epoll on Linux, with an automatic standard-library fallback everywhere else — while keeping a routing and middleware API you already know from Gin and Echo.

This is the goceleris.dev documentation site. Every page is plain, static HTML and crawling is welcome (see /robots.txt). For the entire documentation as one Markdown document, fetch https://goceleris.dev/llms-full.txt.

## Getting Started

- [Introduction](https://goceleris.dev/docs/introduction): What Celeris is, who it's for, and how the documentation is organized.
- [Getting started](https://goceleris.dev/docs/getting-started): Install Celeris, build and run your first server, and understand the request lifecycle.
- [Core concepts](https://goceleris.dev/docs/core-concepts): The Server, Context, handlers, the protocol x engine model, and async dispatch — the model behind everything else.

## Routing & Handlers

- [Routing](https://goceleris.dev/docs/routing): Register routes, path params and wildcards, groups, named routes and reverse URLs, and route-level options.
- [Handling requests](https://goceleris.dev/docs/request-handling): Read the method, path, query, headers, cookies, body, forms, and file uploads from the Context.
- [Binding and validation](https://goceleris.dev/docs/binding-and-validation): Deserialize JSON/XML request bodies into structs and validate input before using it.
- [Sending responses](https://goceleris.dev/docs/responses): Write JSON, XML, HTML, text, blobs, redirects, files, and negotiate content types.
- [Error handling](https://goceleris.dev/docs/error-handling): Return errors from handlers, map them to HTTP responses, centralize handling, and recover from panics.
- [Serving files and static assets](https://goceleris.dev/docs/static-files): Serve single files, directory trees, embedded filesystems, downloads, and static sites safely.

## Middleware

- [Middleware](https://goceleris.dev/docs/middleware): How middleware works in Celeris, the install model, ordering rules, and the full catalog.
- [Security middleware](https://goceleris.dev/docs/middleware-security): Security headers, CORS, CSRF protection, and reverse-proxy header trust.
- [Authentication middleware](https://goceleris.dev/docs/middleware-auth): HTTP Basic, API key, JWT (HMAC/RSA/ECDSA/JWKS), and server-side sessions.
- [Rate limiting and resilience](https://goceleris.dev/docs/middleware-traffic): Protect services under load with rate limiting, circuit breakers, timeouts, adaptive overload shedding, body limits, and request coalescing.
- [Compression, caching, and content](https://goceleris.dev/docs/middleware-content): Response compression, ETag conditional responses, response caching, Protocol Buffers, and OpenAPI docs.
- [URL rewriting and request preprocessing](https://goceleris.dev/docs/middleware-routing-helpers): Pre-routing middleware: reverse-proxy headers, redirects, regex rewrites, method override, and health checks.

## Real-Time

- [Streaming responses](https://goceleris.dev/docs/streaming): Incremental output with StreamWriter, detaching connections, hijacking, and the buffered Stream helpers.
- [Server-Sent Events](https://goceleris.dev/docs/sse): Stream events to browsers with the SSE middleware: heartbeats, slow-client policies, brokers, and Last-Event-ID replay.
- [WebSocket](https://goceleris.dev/docs/websocket): Build real-time WebSocket endpoints with the native, zero-dependency websocket middleware.

## Data & Integration

- [Stores and database drivers](https://goceleris.dev/docs/data-stores): The pluggable KV store interface, in-memory and Redis backends, and event-loop-colocated database drivers.
- [Using net/http handlers and middleware](https://goceleris.dev/docs/net-http-interop): Adapt existing net/http handlers and middleware, and mount Celeris under the standard library.

## Reference

- [Configuration reference](https://goceleris.dev/docs/configuration): Every Config field, its default, and what it does — timeouts, limits, protocol, engine, and callbacks.
- [Engines and the I/O model](https://goceleris.dev/docs/engines): io_uring, epoll, the adaptive controller, the std fallback, and how the engine relates to protocol and async dispatch.
- [Context API reference](https://goceleris.dev/docs/context-api-reference): A categorized index of every Context method for request reading, response writing, and connection control.

## Operations

- [Deployment and TLS](https://goceleris.dev/docs/deployment): Run Celeris in production: TLS termination, reverse proxies, health checks, containers, and tuning.
- [Graceful shutdown and zero-downtime restarts](https://goceleris.dev/docs/graceful-shutdown): Drain in-flight requests on shutdown and hand off the listening socket for zero-downtime deploys.
- [Observability](https://goceleris.dev/docs/observability): Logging, request IDs, metrics (built-in Collector, Prometheus, OpenTelemetry), and profiling.
- [Performance and high load](https://goceleris.dev/docs/performance): Get the most throughput, keep the hot path allocation-free, choose sync vs async, and survive extreme load.
- [Testing](https://goceleris.dev/docs/testing): Unit-test handlers and middleware with celeristest, and assert on responses.

## Benchmarks

- [Benchmarks dashboard](https://goceleris.dev/benchmarks): Interactive throughput, latency-at-SLO, tail latency, memory and CPU for Celeris vs competitor frameworks across languages, averaged over every cluster run per release.
- [Methodology](https://goceleris.dev/methodology): How the benchmark numbers are produced — the cluster, the two run modes (saturation and rated), the signals measured, and the fairness rules.

## Optional

- [Full documentation (one file)](https://goceleris.dev/llms-full.txt): Every doc page concatenated as Markdown.
- [Source — celeris](https://github.com/goceleris/celeris): The engine source on GitHub.