ESLint vs RuboCop
Which should you use? A side-by-side look at what each one does, who it suits, what it costs, how hard it is to set up, and where each falls short.
Open source · MIT
A JavaScript linter that finds and reports problematic code patterns, with rules you can configure.
Open source · MIT
A Ruby linter and auto-formatter that checks code against the community Ruby style guide.
The short answer
Choose ESLint if you need…
- JavaScript developers who want automatic checks on their code
- Teams that want consistent rules enforced in a shared configuration
- Projects that need to customize which code patterns are flagged
- Developers working with React who add a React-specific plugin on top
Choose RuboCop if you need…
- Ruby developers who want consistent style across a project
- Teams that want an automated check on code style during development
- Maintainers of Ruby projects who want to follow the community Ruby Style Guide
- People who want to upgrade or clean up an existing Ruby codebase
Side-by-side
| ESLint | RuboCop | |
|---|---|---|
| Type | Dev tool | Dev tool |
| Price | Free and open source | Free and open source |
| Licence | MIT | MIT |
| GitHub stars | 27.6k | 12.9k |
| Setup difficulty | Intermediate | Beginner |
| How you get it | Install with a package manager | Install with a package manager |
| Main language | JavaScript | Ruby |
| Last code update | 4 days ago | 4 days ago |
What each one is
ESLint
ESLint is a tool that scans JavaScript (ECMAScript) code and reports patterns that may be problems or bad practice. It works by parsing code into a syntax tree and checking it against rules, and every rule is a pluggable piece you can turn on, off, or adjust. Developers use it to catch mistakes and keep code style consistent across a project.
RuboCop
RuboCop is a static code analyzer for Ruby, sometimes called a linter, and a code formatter. Out of the box it enforces many guidelines from the community Ruby Style Guide. Besides reporting problems, it can automatically fix many of them, and most of its behavior can be changed through configuration options.
Best for
ESLint
- JavaScript developers who want automatic checks on their code
- Teams that want consistent rules enforced in a shared configuration
- Projects that need to customize which code patterns are flagged
- Developers working with React who add a React-specific plugin on top
RuboCop
- Ruby developers who want consistent style across a project
- Teams that want an automated check on code style during development
- Maintainers of Ruby projects who want to follow the community Ruby Style Guide
- People who want to upgrade or clean up an existing Ruby codebase
Strengths
ESLint
- Highly pluggable: every rule is a plugin and rules can be added at runtime, per the README
- Mature and widely used, with an MIT license and about 27,600 GitHub stars
- Clear three-level severity model (off, warn, error) that controls the exit code
RuboCop
- Enforces many rules from the community Ruby Style Guide with little setup
- Can automatically correct many issues it reports
- Highly configurable and stable between minor versions, according to the README
Not ideal for
ESLint
- People who only want code formatting; the README says Prettier is the formatter and ESLint is a linter
- Users of experimental or non-standard syntax without a suitable parser, since ESLint officially supports only the latest final ECMAScript standard
- Environments that cannot run a supported Node.js version (^20.19.0, ^22.13.0, or >=24)
RuboCop
- Non-Ruby projects, since it only analyzes Ruby code
- People who do not want to maintain a configuration file, because many aspects of its behavior are set through configuration options
- Projects on Ruby versions outside the supported runtimes (MRI 2.7+ or JRuby 9.4+), since the README lists these as the officially supported implementations
Trade-offs
ESLint
- Requires a supported Node.js version and, for TypeScript type definitions, TypeScript 5.3 or later
- Does not lock dependency versions by design, so behavior can change as dependencies update
- Parser officially supports only the latest final ECMAScript standard; newer experimental syntax may need other parsers
RuboCop
- Configuration is extensive, so tuning it for a project takes effort
- The README notes that the project is financially supported through donations and sponsorships, so its development pace depends on funding
- Supported runtimes are limited to MRI 2.7+ and JRuby 9.4+ per the README
Getting started
ESLint
Install and configure ESLint
npm init @eslint/config@latestRun ESLint on a file
npx eslint yourfile.jsFrequently asked questions
What is the difference between ESLint and RuboCop?
ESLint: A JavaScript linter that finds and reports problematic code patterns, with rules you can configure. RuboCop: A Ruby linter and auto-formatter that checks code against the community Ruby style guide. ESLint suits javascript developers who want automatic checks on their code, while RuboCop suits ruby developers who want consistent style across a project.
Are ESLint and RuboCop free?
ESLint: Free and open source. RuboCop: Free and open source.
Which is easier to set up, ESLint or RuboCop?
RuboCop is easier to get started with (rated beginner); ESLint is rated intermediate and usually needs more setup.
Is ESLint or RuboCop more popular?
ESLint has more GitHub stars (27.6k) than RuboCop (12.9k). Popularity isn't the same as fit — check which one matches your use case above.
What are other alternatives to ESLint and RuboCop?
Other options people compare them with include typescript-eslint, Prettier, standard, lint-staged.
Keep comparing
Built from our catalogue entries for both products: open-source details come from each project's README (AI-assisted, refreshed weekly) and GitHub data; AI-tool details are editorial. Spotted something wrong? Let us know from either product's page.