What people build with simoom

simoom is a library you build into a program, not a server you configure. That makes it a good fit where the HTTP layer has to be small, start fast, stay out of the way of the rest of the program, or be read line by line. Each page below describes the job, shows the code, gives the measured numbers and says plainly where simoom stops.

Six places simoom fits

Edge and IoT devices

A status API and live readings on a gateway with little RAM and a firmware image that has to stay small. TLS without a C toolchain.

215 KB for HTTP/1.1 http1 · sse · features · limits

Serverless functions

Scale to zero without paying for the HTTP layer on every cold start. The default build sat at 901 KB at rest in campaign 4.

0.94 ms to the first answer, first of 21 servers cold start · scale to zero · containers

CLI and desktop apps

An OAuth callback, a local dashboard, live updates over WebSocket or server-sent events, with no async runtime.

0 runtimes to set up defer · websocket · sse · windows

Integration engines

Webhooks and APIs all day, with slow calls sent off the loop and answered from the host's own threads. This is how Cameleer uses it.

33% less CPU per request than Cameleer's old server defer · blocking · offload pool · Cameleer

Audited environments

Every line from the TLS handshake to QUIC congestion control in one repository, under one licence. unsafe in one crate.

0 third-party crates std only · forbid(unsafe_code) · h2spec · HTTP Garden

HTTP/3 services

QUIC on the same port number as TLS, without quinn, rustls or nginx in front. In campaign 4 H2O answered 43% more HTTP/3 requests than simoom, and simoom 1.65x as many as quinn with h3.

54 of 58 interop pairs http3 · quic · tls · alt-svc

Where simoom does not fit

Some jobs need a product, not an engine. For these, pick something else.

Serving a website from files

simoom has no static-file server, no reverse proxy and no configuration file. nginx, Caddy and h2o do those jobs well.

A large web application framework

simoom has a router and a few optional helpers (cookies, CORS, multipart, auth). If you want extractors, middleware stacks and a big ecosystem, axum and actix-web are the better choice. See the comparisons.