Open-source alternatives to Pyrefly

c3c is the compiler for the C3 programming language, transforming source code into executable binaries, static libraries, or dynamic libraries using an LLVM backend. It implements a system based on result-based error handling, scoped memory pooling, and a semantic macro system. The compiler provides first-class support for hardware-backed SIMD vectors that map directly to processor instructions and enables runtime polymorphism through interface-based dynamic dispatch. The project covers a broad set of low-level capabilities, including manual and pooled memory management, inline assembly inte

This project is a functional programming compiler and JavaScript transpiler that transforms a statically typed language into optimized JavaScript for web browsers. It serves as a frontend architecture framework, providing a static type system and a package manager that enforces semantic versioning. The compiler uses a type-checking engine with automatic type inference to prevent runtime errors and guide code refactoring. It implements a structural pattern for managing application state and rendering user interfaces through a virtual DOM, utilizing immutable data and purity-based state transit

ZLS is a language server for the Zig language that implements the Language Server Protocol to provide IDE-like intelligence. It functions as a code intelligence provider, static code analysis tool, and automated refactoring engine for Zig projects. The server integrates directly with the Zig compiler toolchain to derive precise type information and perform semantic analysis. It uses this integration to surface real-time compilation errors as editor diagnostics and to provide semantic syntax highlighting based on resolved types rather than regex patterns. The project covers a wide range of de

Tinymist is a comprehensive suite of tools for Typst document authoring, serving as a language server, document compiler, and project manager. It provides a standardized language service via the Language Server Protocol to enable editor features such as autocompletion, navigation, and semantic highlighting. The project distinguishes itself by integrating a TCP-based live preview server for real-time visual rendering and an advanced static analysis tool that utilizes abstract syntax trees and bidirectional type checking. It also includes a project management system capable of handling multi-fi

Zed is a terminal-based code editor built in Rust that provides a full-featured editing experience with familiar keybindings, mouse support, and multiple cursors. It runs entirely in the terminal while offering capabilities typically found in graphical editors, including split panes, a command palette, and integrated language server protocol support for real-time diagnostics, completions, go-to-definition, and code actions across multiple languages. The editor distinguishes itself through a plugin system that runs sandboxed TypeScript plugins in a QuickJS runtime, with an asynchronous bridge

The Concise TypeScript Book: A Concise Guide to Effective Development in TypeScript. Free and Open Source.

This project is a localized educational resource for learning the Rust programming language, providing a comprehensive guide and technical specifications translated into Simplified Chinese. It serves as an instructional tool for studying language idioms, memory management, and type systems. The repository focuses on software documentation localization, converting official guides into Simplified Chinese to increase accessibility for non-English speakers. It utilizes a markdown-based system to organize content and supports multi-format export to static HTML, PDF, and EPUB formats for both web a

This project is a high-performance static type checker and comprehensive development toolkit for Python. It functions as a core analysis engine that identifies type inconsistencies and enforces code correctness, while simultaneously providing a language server implementation to deliver real-time diagnostics and intelligence directly within development environments. The tool distinguishes itself through a parallelized execution engine that maximizes performance across large-scale codebases and monorepo structures. It supports gradual type adoption, allowing developers to integrate type checkin

Rust-analyzer is a language server implementation that provides real-time code intelligence, static analysis, and development productivity tools for the Rust programming language. It functions as a backend engine that communicates with text editors to deliver deep structural understanding of source code, enabling features like semantic analysis, symbol navigation, and automated refactoring. The project distinguishes itself through a core engine designed for high-performance responsiveness, utilizing incremental query-based compilation and lazy demand-driven evaluation to minimize resource con

mypy is a static type checker for Python that analyzes source code to detect type errors and inconsistencies without executing the program. It functions as a static analysis tool and type inference engine, providing a gradual typing system that allows type hints to be added to a codebase incrementally while maintaining compatibility with dynamic typing. The project distinguishes itself through a combination of performance and precision features. It utilizes a daemon-based incremental checking system and multi-process parallel analysis to manage large codebases, supported by binary cache persi

RuboCop is a static code analyzer, linter, and formatter for the Ruby language. It detects style violations, potential bugs, and code smells by scanning source code without executing the program. The tool enforces a predefined Ruby style guide by flagging deviations and automatically rewriting source code to ensure consistency across projects. It includes a language server that provides real-time analysis and formatting suggestions directly within text editors.

This project is a suite of specialized tools for the implementation of a language server, template parsing, and static type validation of single-file components. It provides a language server and a type checker to deliver consistent intelligence and validation for Vue components across different editors and command-line environments. The tooling utilizes a template parser to transform single-file component structures into virtual code, enabling static analysis and type checking on HTML-like structures. This process allows for the extraction of component metadata regarding props, events, and s

This project is a structured educational course and interactive tutorial designed to teach the TypeScript type system. It functions as a coding sandbox where users learn through a series of guided exercises and challenges that are verified using an automated local test runner. The curriculum covers a progression of skills starting with basic typing fundamentals and core language patterns. It advances into generic abstractions, complex type transformation techniques, and advanced type programming. The material also includes practical applications of software engineering patterns, such as bran

Reason is a strongly typed functional language and multi-target compiler designed to produce either JavaScript for web environments or native machine code for operating systems. It serves as an OCaml-compatible language that shares an abstract syntax tree with OCaml, providing a practical syntax for the OCaml ecosystem. The project functions as a type-safe frontend language, incorporating JSX support to build user interfaces through structural elements that translate into type-safe function calls. It enables deep integration with the JavaScript ecosystem, allowing the use of existing librarie

This project is a comprehensive guide and educational resource for the TypeScript language. It covers the fundamental principles of the language, including its structural type system, static type analysis, and the process of transpiling typed source files into JavaScript. The material details how to model complex data and reusable type logic using generics, conditional types, and mapped types. It also explains the use of declaration files to provide type safety for external JavaScript libraries and the integration of type checking into existing JavaScript projects via JSDoc annotations. The

GraphiQL is an interactive browser-based integrated development environment for writing, testing, and documenting GraphQL queries and mutations. It functions as a code editor, an API exploration tool, and a schema explorer, providing a visual interface for browsing GraphQL types and fields. The project provides a language server that delivers schema-driven autocompletion, linting, and validation via the Language Server Protocol. It allows for the embedding of high-performance editors into external projects and supports the injection of custom tools and components through a sidebar plugin API.

RLS is a language server that provides language intelligence for the Rust programming language. It implements the Language Server Protocol to enable a standardized communication layer between the Rust compiler and various editor clients. The project focuses on providing real-time code completions, symbol navigation, and type information. It also supports automated structural changes, such as workspace-wide symbol renaming, to maintain semantic correctness during refactoring. The system incorporates static code analysis for linting and formatting, alongside a mechanism for incremental compila

Ale is an asynchronous code analysis tool and integrated development environment plugin designed for lightweight text editors. It functions as a language server protocol client, enabling real-time code intelligence and diagnostic feedback by running analysis tasks in the background to ensure the editor interface remains responsive during intensive operations. The plugin utilizes an event-driven architecture to monitor text buffers and trigger linting or formatting routines automatically. It distinguishes itself through a modular extensibility framework that supports a wide range of language-s

Awesome autocompletion, static analysis and refactoring library for python

Phan is a static analyzer and type checker for PHP that identifies bugs and type incompatibilities without executing the code. It serves as a quality gate for continuous integration pipelines and a tool for verifying type safety, specifically checking union types, generics, and array shapes. The project is distinguished by its use of a background daemon and Language Server Protocol implementation, which provide real-time diagnostics and navigation within editors. It also features a baseline-based suppression system that allows developers to record existing errors in a snapshot file to focus e

Carp is a statically typed Lisp compiler that compiles Lisp-like syntax directly to C source code, enabling seamless integration with existing C libraries and low-level system programming. It manages memory deterministically at compile time using ownership tracking and linear types, eliminating garbage collection pauses and runtime overhead while ensuring type safety through an inferred static type system. The language distinguishes itself through compile-time macro expansion and metaprogramming capabilities, allowing code generation and transformation before final binary output. It enforces

This project is a language extension for VS Code that provides comprehensive Go language support. It functions as a language server client, a debugger interface, and a toolchain manager to facilitate Go application development. The extension distinguishes itself by integrating a full suite of toolchain management capabilities, allowing for the installation and configuration of required binaries, linters, and compiler versions directly within the editor. It also provides deep integration for interactive debugging via Delve, supporting remote target debugging, process attachment, and program st

The IntelliJ Platform is a modular framework designed for building desktop integrated development environments. It provides the core infrastructure necessary to create specialized coding tools, including a virtual file system for tracking project sources, a text editor, and a cross-platform graphical user interface framework. The platform distinguishes itself through a component-based architecture that allows developers to extend core application behavior via independent functional units. It supports the creation of custom development environments by integrating language analysis logic, enabl

RuboCop is a static code analyzer, linter, and formatter for the Ruby language. It identifies style violations, smells, and errors in source code to ensure consistency and maintainability based on community guidelines. The project provides automatic source code formatting to rewrite files according to defined stylistic standards. It also functions as a language server protocol implementation, surfacing violations and suggested fixes directly within code editors. The tool covers code complexity monitoring to track the size of classes and methods and employs non-inclusive language detection to

This project is a comprehensive productivity guide and configuration reference for the VS Code editor. It provides a curated collection of shortcuts, configuration tips, and tutorials designed to improve efficiency and optimize the daily coding workflow. The resource covers advanced AI-assisted development, including the integration of autonomous agents, custom prompt files, and AI-powered coding assistants for task automation and code generation. It also provides specialized guidance on integrated terminal management, such as configuring shell profiles and automating command execution. Addi

CppGuide is a curated collection of educational resources and practical guides focused on C++ server development, Linux kernel internals, concurrent programming, network protocols, and security exploitation. It provides structured learning paths for backend developers, covering everything from interview preparation to building high-performance network servers and understanding operating system fundamentals. The guide distinguishes itself by offering in-depth, hands-on tutorials that walk through real-world implementations, including building a Redis-like server from scratch, designing custom