Is YJIT enabled by default?

Yes. Apps on Ruby 4 run with YJIT enabled — up to 30% speedup compared to Ruby 3.3.

How do I configure Rails or Puma?

Use START=bundle exec puma -C config/puma.rb in squarecloud.app . Bundler resolves gems automatically before start.

Yes. Run your main app with a subdomain and a separate background app for Sidekiq, or both in the same process via the Puma plugin.

Which exact Ruby version runs?

Ruby 4 , with security patches applied automatically. We standardized on major 4 only because YJIT matured, the garbage collector became concurrent, and ractors finally deliver real parallelism — idiomatic apps run up to 40% faster than the 3.x line. We don't keep older majors in parallel to guarantee security-patch SLAs and operational simplicity.

Ruby 4 with Bundler built-in

Run Sinatra, Rails, or your favorite scripts. YJIT enabled — apps up to 30% faster.

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Why run on Square Cloud

Everything optimized, production-ready.

YJIT enabled

Apps up to 30% faster than previous Ruby versions.

Automatic Bundler

Detects Gemfile and installs gems before start.

Rails, Sinatra, Hanami, Roda, Grape

All major frameworks supported.

Sidekiq and workers

Native background processing, configurable via START=.

Ideal use cases

Where this runtime shines on our platform.

Rails 7 and Hotwire web apps

Full-stack or API-mode hosting with Turbo, Stimulus, and import maps in production.

Lightweight APIs with Sinatra and Roda

Minimal Ruby microservices with superior performance, simple deploys, and low overhead.

Discord bots with discordrb

Ruby bot hosting with auto-restart, real-time logs, and gem management.

Sidekiq and Resque workers

Robust async processing with Redis, smart retries, and monitoring dashboards in production.

Scrapers and web automation

Data collection with mechanize, nokogiri, httparty, and Watir in automated workflows.

E-commerce with Spree and Solidus

Open-source Ruby e-commerce platforms with customizable checkout and integrated payment gateways.

Available versions

Pick the track that best fits your project.

Current version

Single stable toolchain

Technical specs

Everything you need to configure your app.

Accepted extensions: .rb
Dependency file: Gemfile
RUNTIME= aliases: ruby

Minimal config

Create a squarecloud.app file at your project root:

squarecloud.appRuby

MEMORY=512
DISPLAY_NAME=Meu App
VERSION=recommended
MAIN=app.rb

Frequently asked questions about Ruby Hosting

Ruby 4, YJIT, Bundler, and Rails.

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Ruby 4 with Bundler built-in

Run Sinatra, Rails, or your favorite scripts. YJIT enabled — apps up to 30% faster.

Get started See plans