Open-source alternatives to Validator

Recast is a JavaScript AST parser and printer designed for automated code refactoring. It converts source code into abstract syntax trees that can be modified and then printed back into source code. The project focuses on formatting-preserving transformations, storing original whitespace and indentation metadata within syntax tree nodes to reconstruct code without losing its original layout. It also generates character-level source maps to maintain precise correspondences between original input and transformed output. The toolkit includes utilities for syntax tree manipulation using a visito

Commonmark.js is a library designed to parse and render text formatted according to the CommonMark specification. It functions as a document processing pipeline that converts plain text into structured HTML or an abstract syntax tree, enabling developers to programmatically inspect, modify, and transform document elements. The library distinguishes itself through its strict adherence to standardized parsing rules, ensuring consistent and predictable output across different software environments. It provides a robust framework for document tree manipulation, allowing users to traverse, insert,

This project is a backend service that implements the Language Server Protocol to provide IDE-integrated intelligence for PHP development. It functions as a static analysis tool that parses source code to enable advanced editor features, including autocompletion, symbol navigation, and definition resolution. The server distinguishes itself through its ability to operate within isolated containers and remote development environments. By utilizing a virtual file system abstraction and flexible communication protocols, it maintains project-wide symbol indexing and code analysis even when files a

Semistandard is a static analysis tool and automated code formatter designed to enforce consistent JavaScript syntax and formatting standards across a codebase. It functions as a linter that identifies deviations from established style rules and provides automated corrections to resolve formatting errors without manual intervention. The tool is distinguished by its specific focus on semicolon usage, ensuring that all statements adhere to a uniform syntax standard. It provides comprehensive style management by verifying code against predefined rules and blocking non-compliant submissions withi

WordPress Coding Standards is a collection of rules for the PHP CodeSniffer engine designed to enforce consistent coding conventions and best practices within PHP projects. It functions as a specialized static analysis tool that scans source code to identify style violations, security vulnerabilities, and potential bugs before execution. By integrating into development workflows, it ensures that code adheres to official project conventions, maintaining readability and consistency across large-scale plugin and theme development. The project distinguishes itself through deep domain-specific val

syn is a Rust syntax tree parser and token stream converter. It serves as a toolkit for procedural macro development, providing a framework to parse Rust source code into structured syntax trees for analysis and transformation. The project enables the manipulation of Rust abstract syntax trees through specialized visitor and folder patterns for traversing and mutating nodes. It provides a bidirectional mapping that allows developers to convert token streams into structured trees and print those trees back into tokens for code generation. The library covers a broad range of syntax analysis ca

PHP_CodeSniffer is a static analysis tool, coding standard linter, and command-line validator for PHP. It scans files and directories to detect and report formatting errors and language-specific coding violations without executing the code. The project functions as an automated code formatter capable of correcting detected style and formatting violations to bring source code into compliance with defined standards. It uses token-based lexical analysis to match code patterns against rule sets, ensuring consistency across a codebase. The tool provides comprehensive capabilities for recursive fi

Standard is a suite of static analysis tools for JavaScript, comprising a linter, formatter, and a predefined style guide. It functions as a static code analyzer that scans source code for style violations and potential errors without executing the program. The project provides an automatic code fixer that rewrites source code to resolve formatting issues and enforce syntax consistency. It implements a standardized set of rules for JavaScript formatting and syntax to ensure a uniform appearance across different projects. The system covers a wide range of static analysis capabilities, includi

This project is a CSS linter and static analysis tool designed to identify syntax errors, logic flaws, and problematic patterns in Cascading Stylesheets. It functions as a command line validator that verifies code quality and enforces consistent styling and coding standards without requiring a web browser. The analyzer distinguishes itself by incorporating web accessibility auditing to detect patterns that hinder users with disabilities. It also performs browser compatibility checking to identify non-standard hacks and missing vendor prefixes, and provides performance optimization analysis to

Utopia is a development platform for building React components through a visual interface that synchronizes changes directly with underlying source code. It functions as an AST-based code editor and a visual component editor, using abstract syntax tree manipulation to update files while preserving the original formatting and structure. The project features an in-browser module bundler that compiles and executes JavaScript modules directly within the browser to provide immediate feedback without server-side build steps. It also includes a pull request preview tool for inspecting and validating

Vulture is a static analysis tool and linter designed to find unused variables, functions, and classes in Python source code. It operates as a dead code detector and unused code finder that scans source files to identify unreachable expressions and imports without executing the code. The tool employs a confidence-based heuristic scoring system to assign probability values to detections, helping to distinguish truly unused symbols from potential false positives. It further assists in pruning dead logic by sorting detected unused classes and functions by line count to prioritize the removal of

HCL is a configuration language implementation designed for parsing, evaluating, and encoding structured settings through the use of blocks and attributes. It functions as a configuration AST parser and a schema-based decoder that maps attributes and blocks to internal data structures using predefined rules. The project includes an expression evaluation engine that resolves dynamic values and cross-references through multi-phase processing of variables and functions. It also provides a configuration file formatter to standardize the layout and indentation of source code for consistent visual

Nearley is a JavaScript parser toolkit used to define context-free grammars and generate corresponding parsers. It features an EBNF grammar compiler that transforms language definitions written in extended Backus-Naur Form into executable JavaScript code, utilizing an Earley parser implementation to process any context-free grammar. The toolkit distinguishes itself by its ability to handle left-recursion and ambiguity without failing, allowing it to identify and return multiple valid derivations for a single input string. It also includes a grammar fuzzing generator to produce random strings

This project is an IntelliJ IDE plugin that provides an integrated development environment for Rust. It serves as a build system orchestrator and debugger interface, offering comprehensive language analysis, syntax highlighting, and intelligent code editing assistance. The plugin integrates with a language server to provide real-time type inference and code navigation. It includes a dedicated static analysis tool for detecting code duplicates, analyzing memory leaks, and measuring test coverage. The toolset covers toolchain management and Cargo integration for dependency and manifest handlin

node-jscs is a JavaScript linter and code style checker designed to analyze source code and enforce consistent coding standards. It functions as a static analysis tool that identifies patterns in JavaScript code to ensure adherence to defined style guides. The project provides capabilities for both JavaScript code linting and automated code formatting. It can check source code for style violations and automatically correct those errors to align the codebase with a specified set of formatting rules.

Clean-CSS is a Node.js CSS optimizer that functions as a minifier, bundler, and post-processor. It is designed to decrease total stylesheet volume by removing whitespace, comments, and redundant code. The project provides a pipeline for applying custom transformations and browser compatibility adjustments. It allows for the programmatic modification of CSS rules and values through a plugin system and the use of custom optimization plugins. The tool covers a broad range of asset optimization capabilities, including stylesheet bundling, import rule inlining, and relative URL rebasing. It also

Traceur is a JavaScript syntax transpiler that transforms modern and next-generation language features into compatible versions for older runtime environments. It functions as a compiler that translates proposed language standards and upcoming syntax into current versions to maintain cross-engine compatibility. The project operates as an asynchronous code transformer, converting async functions and generators into promise-based state machines. It includes a functional tail-call optimizer that wraps recursive functions in trampolines to prevent stack overflows and an ECMAScript polyfill engine

CodeQL is a semantic code analysis engine and vulnerability scanning tool that treats source code as data. It utilizes a static analysis query language to define complex patterns and security vulnerabilities within a code graph database. The system represents source code as a relational database, enabling the execution of structural queries and data flow analysis. This approach allows for the detection of security flaws and coding errors across large-scale repositories. The tool provides capabilities for automated code auditing, static analysis security testing, and custom vulnerability dete

Shellharden is a shell script hardening tool and linter designed to improve the security and reliability of Bash scripts. It functions as an automated utility that rewrites scripts to follow industry standards for quoting and security practices. The project provides an optimizer and standardizer that replaces unsafe patterns and aliases with safer functional equivalents. It includes a syntax highlighter that uses visual markers and colorization to indicate vulnerabilities and areas where quoting corrections are required. The tool covers a broad range of capabilities including automated safet

CodeMirror is a browser-based code editor framework and modular extension system used to embed full-featured text editors into web pages. It functions as a syntax tree parsing engine and a language server protocol client, enabling structural language analysis and deep integration with external programming language services. The project is distinguished by its modular architecture, which uses a system of extensions and compartments for dynamic reconfiguration at runtime. It supports real-time collaborative editing and state synchronization through an operational transformation framework, allow

Emmet is a markup code generator and web development productivity toolkit. It serves as an expansion engine that converts shorthand abbreviations and CSS-like selectors into full HTML, XML, and other markup structures. The project features a dedicated CSS shorthand expansion engine that transforms concise property codes into full style declarations, including the automatic generation of vendor prefixes and gradients. It distinguishes itself by offering a programmable expansion process through custom snippet definitions, abbreviation alias mapping, and script-based extensibility. The toolkit

Asciidoctor is a Ruby-based text processing engine and command-line toolchain designed to convert AsciiDoc content into structured publishing formats, including HTML5 and DocBook 5. It functions as a static content publishing toolchain that transforms raw source files into formatted documents. The system utilizes a pluggable converter interface and template-driven output, allowing the default conversion logic to be overridden via custom converters or templates. This enables the generation of specific document structures and the export of content into various publishing formats for diverse dis

This project is a formal markdown specification standard that provides a detailed markup syntax definition and a definitive set of rules for parsing plain text into consistent HTML output. It establishes a standardized grammar for structural blocks and inline elements to ensure uniform rendering across different software implementations. The specification is supported by a parser conformance suite and a reference implementation in C and JavaScript to verify that implementations adhere to the standard. It includes a system for implementation verification that compares transformed input strings

cel-go is a Go implementation of the Common Expression Language, providing a type-safe engine for the evaluation of non-Turing complete, side-effect-free expressions. It functions as an embedded expression engine that converts human-readable strings into type-checked abstract syntax trees to ensure safe execution. The system utilizes a compile-once evaluate-many model, parsing and validating expressions into cached programs for repeated execution across different datasets. It further distinguishes itself as a partial state evaluator, using commutative logic to compute results and return resid

graphql-go is a schema-first GraphQL library and server implementation for Go. It provides a query execution engine and schema parser that converts schema definition strings into executable structures and validates resolver signatures. The library also includes a streaming implementation for real-time GraphQL subscriptions using channels within resolvers. The project distinguishes itself through parallel resolver execution to reduce request latency and the use of buffer-pool memory management to lower garbage collection overhead. It enables the creation of cloneable schema instances from a sh

Goja is a JavaScript engine and ECMAScript compliant interpreter implemented entirely in Go. It serves as an embedded scripting engine that allows Go applications to execute JavaScript code and integrate a programmable scripting layer without relying on Cgo or external native dependencies. The project functions as a bridge between Go and JavaScript, enabling bidirectional data exchange and function invocation. It allows Go hosts to expose native structs, slices, and maps as JavaScript objects and arrays, while providing mechanisms to export script values and functions back into native Go type

markdown-js is a JavaScript markdown parser and converter that transforms markdown text into HTML output. It functions as both a library and a command line interface tool for converting documents. The project is centered on an abstract syntax tree representation, allowing markdown to be parsed into a structured tree for programmatic inspection and modification before the final rendering process. This intermediate representation enables custom markup processing and document transformations. The toolset covers programmatic document parsing, static site generation, and CLI-based file processing