Ruby debug
What it is
Ruby debug is a free, open-source debugger for Ruby MRI 2.7 and later. Its console evaluates Ruby expressions, inspects program state, controls execution, sets conditional or exception breakpoints, and activates 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 such as show_source and show_doc. The rdbg command launches Ruby scripts and commands including Rails, Rake, and RSpec under the debugger. 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 says there is no performance penalty when not stepping and no breakpoints are set. The gem costs nothing and uses the BSD-2-Clause license.
For and against
For
- Supports backward execution replay
- Offers conditional and exception breakpoints
- Remote debugging uses UNIX sockets or TCP/IP
- IRB adds completion and multiline input
- No penalty when idle without breakpoints
Against
- Debugger messages are not encrypted
- Nonstop remote access can create a vulnerability
- Project describes the debugger as not mature
- VS Code requires vscode-rdbg extension
The verdict
Ruby debug provides broad console controls, recording and replay, and remote attachment for supported Ruby versions. Its encryption and remote-access warnings require careful deployment.
Who it suits
It is for Ruby developers debugging MRI 2.7-or-later programs locally or remotely. Users of VS Code or Chrome DevTools can use the described frontends.
Plans and prices
debug (open-source gem)
Ruby MRI 2.7 and later · BSD-2-Clause license
Read 9 Oct 2026 · github.com
On the record
- Debugger controls
- Its console can evaluate Ruby expressions, inspect program state, control execution, set breakpoints, and activate tracing.github.com · read 9 Oct 2026
- Editor integrations
- The README describes debugger frontends for VS Code and Chrome DevTools; VS Code use requires the vscode-rdbg extension.github.com · read 9 Oct 2026
- Install
- The README says to install it with `gem install debug` or add `gem "debug", ">= 1.0.0"` to a Gemfile.github.com · read 9 Oct 2026
- IRB console
- It can use IRB as the debug console, adding autocompletion, multiline input, and IRB commands such as `show_source` and `show_doc`.github.com · read 9 Oct 2026
- 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.github.com · read 9 Oct 2026
- Performance
- The project says it has no performance penalty when not stepping and no breakpoints are set.github.com · read 9 Oct 2026
- Purpose
- The library provides debugging functionality for Ruby (MRI) 2.7 and later.github.com · read 9 Oct 2026
- Recording and replay
- The debugger can record execution and replay it by stepping backward through the execution log.github.com · read 9 Oct 2026
- Remote access risk
- The README warns that `debug/open_nonstop` can create a vulnerability because it opens debugging access without stopping the program.github.com · read 9 Oct 2026
- Remote debugging
- It supports remote debugging over UNIX domain sockets or TCP/IP, with a console that can attach to a running debuggee.github.com · read 9 Oct 2026
- Ruby program use
- The `rdbg` command can launch Ruby scripts or commands such as Rails, Rake, and RSpec under the debugger.github.com · read 9 Oct 2026
- Security limitation
- The README warns that debugger-to-debuggee messages are not encrypted and advises care when using remote debugging.github.com · read 9 Oct 2026
