Steep review

Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026

Ruby teams that want type checks during development can use Steep to compare source code with declarations in RBS signature files. It is an open-source static type checker, not a general-purpose code analysis suite, and it does not require changes to the Ruby runtime. The fit is strongest for developers and teams already adopting RBS who want to identify type errors as part of their workflow; projects seeking security checks or broad code-quality analysis should look elsewhere.

Steep supports gradual typing features including generics, union types, nullable types, and flow-sensitive analysis. Developers configure source and signature paths in a Steepfile, then run checks from the command line. It can also generate prototype RBS declarations from Ruby code, including prototypes based on Sorbet RBI and runtime APIs. These capabilities make it useful both for checking existing signatures and for helping establish them, although signature configuration is part of the work rather than an automatic substitute for defining a type system.

The product is self-hosted and available on Linux, macOS, and Windows. Language-server features support editor integrations for Visual Studio Code, Sublime Text, Vim, and Neovim, while configurable Rake tasks include watch mode. Steep is free and open source, with community and documentation support. Choose it when RBS-based type checking and editor feedback are priorities; avoid it if you need hosted service delivery, autofix, security analysis, or a broader static-analysis tool.

Steep pros and cons

• Where it wins
  • Checks Ruby code against RBS, including generics and nullable types
  • Flow-sensitive checks help catch type errors during development
  • Editor language-server features and configurable Rake tasks
• Where it doesn't
  • Focused on type checking, not general code or security analysis
  • Requires configuring source and signature paths in a Steepfile
  • Self-hosted workflow with community and documentation support

Steep fact sheet, pricing and score →

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Last updated 7 Oct 2026 · How we research and update