RuboCop is a Ruby code style checking and code formatting tool. It aims to enforce the community-driven Ruby Style Guide.

Code style checking for RSpec files. A plugin for the RuboCop code style enforcing & linting tool.

Reek is a tool that examines Ruby classes, modules and methods and reports any code smells it finds.

a code metric tool for rails codes, written in Ruby.

Ruby Style Guide, with linter & automatic code fixer

RubyCritic is a tool that wraps around various static analysis gems to provide a quality report of your Ruby code.

Flay analyzes code for structural similarities. Differences in literal values, variable, class, method names, whitespace, programming style, braces vs do/end, etc are all ignored. Making this totally rad.

Flog reports the most tortured code in an easy to read pain report. The higher the score, the more pain the code is in.

prettier plugin for the Ruby programming language

Fails your build if code quality thresholds are not met

A code linting tool for Chef Infra cookbooks.

Code metrics from Flog, Flay, Saikuro, Churn, Reek, Roodi, Code Statistics, and Rails Best Practices. (and optionally RCov)

Sandi Metz rules checker

Knows how to calculate the SkunkScore for a set of Ruby modules

Roodi parses your Ruby code and warns you about design issues you have based on the checks that is has configured

Static analysis Lint-type tool to improve your OO Ruby code

tailor parses Ruby files and measures them with some style and static analysis "rulers". Default values for the Rulers are based on a number of style guides in the Ruby community as well as what seems to be common. More on this here http://wiki.github.com/turboladen/tailor. tailor's goal is to help you be consistent with your code, throughout your project, whatever style that may be.

metrics and CI are for A students.

Keep bad code out of your projects. Your idea of bad code, no one elses. Outlaw defines an example based DSL for demonstrating anti-patterns and builds a rule for each anti-pattern that it alerts the user to violations when encountered in a project's codebase during scanning. Outlaw is a work in progress and contributions, suggestions and forks are welcome. Outlaw was a personal project for Mendicant University, Session 10 in Jan '12

Computes the CRAP metric for Ruby source code

A simple measure of dependency freshness

Calculates ABC metric for Ruby 1.9. Just like Flog but much more dull.

JSLint JavaScript checker wrapped in a Ruby gem for easier use

Calculates code complexity as a measure of paths through code execution. CI integration and beautiful output options.