Open Source Linters

Ultracite is a highly opinionated, zero-configuration linting and formatting preset designed primarily for modern JavaScript/TypeScript codebases. It is built on top of the Biome toolchain (written in Rust) and aims to deliver sub-second performance so that formatting and linting feel seamless, even on large projects. Because it comes pre-configured with sensible defaults for frameworks like React and Next.js, developers can adopt it with minimal setup—simply run npx ultracite init and start coding. The project emphasizes type-safety and best practices, enforcing stricter rules out of the box so that unsafe or sloppy patterns are discouraged. It also positions itself as “AI-ready,” meaning it’s designed to integrate smoothly into workflows where AI code generation (e.g., from Copilot, Claude Code, etc) is involved, ensuring consistent style across team-written and machine-written code.

PyChecker is a static analysis tool for finding bugs in Python source code. It finds problems that are typically caught by a compiler for less dynamic languages, like C and C++. It is similar to lint.

JCSC is a highly configurable checking tool for your Java source code. It checks the compliance to a defineable coding standard like naming conventions and code structure. Also signs of bad coding, potential bugs are found. JCSC is inspired by lint.

Transmogrify is a code analysis/manipulation tool for Java whose current focus is refactoring. There are also the beginnings of a lint tool and a code twiddler (makes changes to code that aren't refactorings).