Open-source alternatives to Lark

Ohm is a compiler construction toolkit and parser combinator library used to build parsers, interpreters, and compilers. It provides a formal grammar language for specifying the structural rules of data formats to ensure precise parsing of input strings. The project functions as a parsing debugging tool and program execution visualizer. It generates text traces and graphical visualizations to show the step-by-step logic used during parsing and renders runtime state changes and method call hierarchies. The toolkit covers custom parser development and the construction of compilers and interpre

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

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

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

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

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.

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

Optimize-js is a JavaScript parsing optimizer designed to reduce the time browsers spend pre-parsing scripts to improve initial execution speed. It transforms source code to minimize the overhead associated with browser parsing. The project implements a technique that wraps function calls in parentheses to bypass initial pre-parsing and reduce double-parsing overhead. To maintain the utility of the transformed code, it includes a source map generator that links the optimized output back to the original source. The toolset also includes performance benchmarking capabilities to measure the exa

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

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

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

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,

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

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

js-code-to-svg-flowchart is a JavaScript source code visualizer and static code analysis tool that converts programming blocks and iterators into scalable vector graphics flowcharts. It functions as a code-to-diagram converter that maps the structural logic and sequence of operations from source files into visual representations. The system includes a command line interface for generating SVG flowcharts directly from local source code. It features a transformation engine that maps code nodes to schematic shapes and supports a sequence of images at varying abstraction levels to explain logic s

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

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

The validator is a reference static analysis tool and language specification checker designed to verify that JavaScript source code strictly adheres to the defined grammar, type rules, and structural requirements of the asm.js subset standard. By inspecting source files without execution, it acts as a syntax linter that catches structural errors, malformed syntax, and standard violations early. The tool parses source code into hierarchical token structures to analyze grammatical correctness and language feature usage. It measures code against formal grammar definitions and matches programmati

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

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

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

Semantic is a Haskell-based library and command-line tool designed for polyglot source code analysis. It functions as a static program analysis framework and a polyglot abstract syntax tree parser that converts multiple programming languages into structured syntax trees based on grammar definitions. The system distinguishes itself through a semantic code comparison engine that detects structural and meaningful changes between code versions rather than relying on textual differences. It further enables analysis across different programming syntaxes by translating surface languages into a unifi