Puma

puma.io · checked 7 Oct 2026

#24 · Web Server Software

Visit puma.io ↗ Alternatives Puma vs OpenLiteSpeed

How it plugs in

—Public API

NoOpen source

YesFree tier

Signal on Web Server Software6.0#24 of 36

Puma is a fast, concurrent HTTP 1.1 server designed for Ruby/Rack applications.

Pricing

PumaOpen-source Ruby/Rack web server · BSD 3-Clause licenseFree

As puma.io lists them, checked 7 Oct 2026.

Near it

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Runs on

Web
Windows
Mac
Linux
iOS
Android

Facts

Website: puma.io
Price: Free tier
Free trial: No
Concurrency: Puma serves requests in separate threads and can use pre-forked worker processes in cluster mode.
Deployment: The deployment guide says Puma can be used as a development server, though most users run it in production deployments.
Founded: 2011
Frameworks: Puma is the default server for Ruby on Rails and can also run Sinatra applications.
Integrations: The documentation lists community plugins for exporting metrics to Prometheus and sending metrics to StatsD.
License: Puma is licensed under the BSD 3-Clause license.
Monitoring: Puma includes a built-in status and control app, and its docs describe using process monitors such as systemd or rc.d.
Ruby implementations: Puma works with MRI Ruby and JRuby, and the documentation also names TruffleRuby as a truly parallel Ruby implementation.
Security support: The security policy supports the latest release in the 8.x and 7.x series and marks all other releases unsupported.
SSL requirement: Puma supports SSL sockets when OpenSSL development files are installed; without them, it installs but does not allow SSL connections.
Standalone: Puma supports SSL, zero-downtime rolling restarts, and a built-in request bufferer, allowing deployment without a reverse proxy.
Vulnerability reporting: The security policy directs vulnerability reports to GitHub or Evan Phoenix.

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