Open-source alternatives to Lark

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

Unified is a syntax tree processing engine and content ecosystem designed to parse, transform, and serialize text content. It functions as a plugin-based content pipeline that converts raw text into structured abstract syntax trees using plain JavaScript objects for programmatic inspection and modification. The project distinguishes itself through a modular architecture that enables cross-ecosystem translation, allowing syntax trees to be converted between different specifications such as HTML and Markdown. It utilizes a system of immutable processor cloning and shared state containers, ensur

Jison is a JavaScript parser generator that implements the LALR parsing algorithm. It creates tools to analyze custom programming languages by converting structured input into tokens and trees. The project functions as a Bison-compatible generator, accepting grammars in a format compatible with the Bison parser generator to produce JavaScript parsers. It covers the requirements for compiler frontend development, including the implementation of domain-specific languages and syntax analysis tooling. Its capabilities extend to custom language parsing and the generation of parsers via a command

TSDoc is a documentation standard and specification for writing structured comments in TypeScript code. It provides a portable system for defining metadata, tags, and cross-references within source code to ensure consistent parsing and rendering across different tooling. The project includes a doc comment parser that converts comments into a structured syntax tree and a validator that enforces syntax consistency. It allows for the definition of custom documentation tags through external configuration files and supports multiple syntax validation modes to assist with specification compliance.

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

go-ast-book is a collection of educational and technical resources focused on abstract syntax tree analysis, compiler development, and static code verification. It provides guides and manuals for parsing, traversing, and analyzing Go source code to extract semantic meaning. The project serves as a reference for building compiler frontends, covering the translation of high-level code into intermediate representations and single static assignment forms. It also provides instructions for using these techniques to develop language tooling and perform static code analysis. The resources cover a b

This project is a CSS stylesheet compiler that transforms Sass source code into standard CSS. It provides the primary mechanism for converting styles while implementing syntax rules for web browsers and applications. The compiler supports a module-based dependency system that uses dedicated namespaces to provide encapsulation and prevent global scope collisions. It includes specialized engines for multi-model color conversion and advanced mathematical calculations, including trigonometry and logarithms. Capabilities cover a broad range of build and analysis tools, including the generation of

Esprima is a JavaScript parser that converts source code into a structured abstract syntax tree. It implements a specification-driven grammar to ensure compliance with ECMAScript standards, enabling the programmatic analysis and transformation of JavaScript programs. The project provides capabilities for lexical tokenization to break source code into individual symbols and static syntax validation to verify that scripts are well-formed without executing the code. Its functional surface covers JavaScript static analysis, lexical analysis, and the generation of abstract syntax trees.

The ECMAScript specification is the formal standard defining the syntax, semantics, and execution model that all JavaScript implementations must follow. It establishes the official language rules through a combination of formal grammar and step-by-step algorithmic prose. The project manages the technical evolution of the language via a consensus-driven governance framework and a staged proposal pipeline. This process tracks features from initial design through expert reviewer sign-off and committee approval. A specification-as-code toolchain compiles these formal definitions and algorithmic d

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

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

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

This project is an AI-powered code reviewer and static analysis server that identifies low-quality files and generates automated critiques. It functions as an automated quality scoring tool that evaluates source code structure and complexity through local parsing. The system utilizes a standardized context protocol to stream analysis results to AI agents and editors. It integrates large language models to produce automated reviews and suggestions for improvement based on quantitative quality metrics. The tool includes a weight-based scoring engine and an asynchronous analysis pipeline for pr

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

Pyre is a high-performance static type checker and analysis tool for Python. It identifies type errors and ensures type safety without executing the program, utilizing a static type inference engine to maintain consistency across functions. The project is distinguished by an incremental type analysis engine that operates as a background daemon. This system monitors filesystem changes to re-validate only modified parts of a project, reducing the time required for repeated analysis. It also includes a static analysis security tool that uses taint analysis to track untrusted data flows and ident

JSHint is a JavaScript static analysis tool and linter designed to detect errors and enforce coding standards. It functions as a syntax validator that scans source code to identify potential logic problems and programming mistakes before the code is executed. The tool provides a command line interface for analyzing files and directories. It supports the export of analysis results into standardized formats such as Checkstyle for integration with external build tools. Analysis is managed through a system of linting rule management and environment global configuration. This includes the ability

pycparser is a C99 parser library that converts C source code into an abstract syntax tree consisting of Python objects. It functions as an abstract syntax tree generator, transforming preprocessed C code into a structured hierarchy for programmatic analysis and transformation. The library integrates with a C preprocessor to handle directives before parsing. It also features a stub header parser, which uses minimal mock headers to allow the parsing of C code without requiring a full system C library installation. The project provides tools for static code analysis, C program analysis, and so

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

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

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

Expr is a high-performance expression evaluation engine and language for Go applications. It functions as a dynamic rule engine that parses and executes custom logic and data validations at runtime without requiring the application to be recompiled. The system utilizes a sandboxed logic executor to run expressions without side effects. It ensures program termination by employing instruction-level loop detection to prevent infinite loops and isolates the evaluation process from the host system. The engine employs a bytecode-based virtual machine and abstract syntax tree analysis to achieve ex

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

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

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

Dalfox is an automated web application security tool specifically designed for discovering and verifying cross-site scripting vulnerabilities. It functions as an XSS vulnerability scanner that analyzes HTTP parameters and DOM structures to identify reflected, stored, and blind injection points. The project distinguishes itself by providing a Model Context Protocol server and a REST API, allowing artificial intelligence agents and remote interfaces to trigger and manage security scans programmatically. It utilizes a payload mutation engine and fingerprinting strategies to execute WAF evasion t

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

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