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Ruby debug

github.com

Free plan LinuxSelf-hosted
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Spec score 7.3 #20 of 27 in Debuggers

What it is

Ruby debug is a free, BSD-2-Clause open-source debugger for Ruby MRI 2.7 and later, delivered for Linux and self-hosted use. Its console evaluates Ruby expressions, inspects program state, controls execution, sets conditional and exception breakpoints, and enables tracing. The debugger can record execution and replay it by stepping backward through the log. Remote sessions work over UNIX domain sockets or TCP/IP, allowing a console to attach to a running program. An IRB console adds autocompletion, multiline input, and commands including `show_source` and `show_doc`. The `rdbg` command launches Ruby scripts and commands such as Rails, Rake, and RSpec under debugging. Frontends are described for VS Code and Chrome DevTools; VS Code requires the vscode-rdbg extension. Installation uses `gem install debug` or a Gemfile entry. The project reports no performance penalty when not stepping and with no breakpoints set. It warns that remote messages are unencrypted and that `debug/open_nonstop` can expose access without stopping the program.

Spec sheet

Purpose
The library provides debugging functionality for Ruby (MRI) 2.7 and later.Read 9 Oct 2026 · github.com
Debugger controls
Its console can evaluate Ruby expressions, inspect program state, control execution, set breakpoints, and activate tracing.Read 9 Oct 2026 · github.com
Editor integrations
The README describes debugger frontends for VS Code and Chrome DevTools; VS Code use requires the vscode-rdbg extension.Read 9 Oct 2026 · github.com
Install
The README says to install it with `gem install debug` or add `gem "debug", ">= 1.0.0"` to a Gemfile.Read 9 Oct 2026 · github.com
IRB console
It can use IRB as the debug console, adding autocompletion, multiline input, and IRB commands such as `show_source` and `show_doc`.Read 9 Oct 2026 · github.com
License and support
The repository displays a BSD-2-Clause license and invites bug reports and pull requests, while describing the debugger as not mature.Read 9 Oct 2026 · github.com
Performance
The project says it has no performance penalty when not stepping and no breakpoints are set.Read 9 Oct 2026 · github.com
Recording and replay
The debugger can record execution and replay it by stepping backward through the execution log.Read 9 Oct 2026 · github.com
Remote access risk
The README warns that `debug/open_nonstop` can create a vulnerability because it opens debugging access without stopping the program.Read 9 Oct 2026 · github.com
Remote debugging
It supports remote debugging over UNIX domain sockets or TCP/IP, with a console that can attach to a running debuggee.Read 9 Oct 2026 · github.com
Ruby program use
The `rdbg` command can launch Ruby scripts or commands such as Rails, Rake, and RSpec under the debugger.Read 9 Oct 2026 · github.com
Security limitation
The README warns that debugger-to-debuggee messages are not encrypted and advises care when using remote debugging.Read 9 Oct 2026 · github.com

Plans and prices

debug (open-source gem) Free Ruby MRI 2.7 and later · BSD-2-Clause license Read 9 Oct 2026 · github.com

Every Ruby debug plan and price →

Strong points and limits

Strong points

  • Supports conditional and exception breakpoints
  • Records execution for backward replay
  • Remote debugging uses UNIX sockets or TCP/IP
  • IRB adds completion and multiline input
  • No stated penalty when idle without breakpoints

Limits

  • Project describes the debugger as not mature
  • Remote debugger messages are not encrypted
  • `debug/open_nonstop` can expose debugging access
  • VS Code requires the vscode-rdbg extension

Who it suits

It suits Ruby developers working with MRI 2.7 or later who need console inspection, remote sessions, recording and replay, or editor frontends. It is also suitable for users who prefer an open-source gem.

Verdict

Ruby debug provides a broad Ruby debugging console with remote operation, replay, and integrations. Its open-source licensing and free price are paired with explicit maturity and remote-security warnings.

Where Specifiction places it

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