Directory

Open Source Packages

Libraries, frameworks, tools, and SDKs used by the apps in this directory — scored the same way as the apps themselves.

5929 packages

All Packages

91Health
Tool npm

prettier

An opinionated code formatter that enforces consistent style across every language your project speaks.

52,316
MIT
Used by 310
78Health
Tool npm

eslint-plugin-import

ESLint rules that validate ES module import/export syntax and catch broken paths before they hit your build.

5,947
MIT
Used by 116
96Health
Framework PyPI

pytest

The Python testing framework that makes writing small tests easy and scales to complex functional test suites.

14,543
MIT
Used by 100
91Health
Tool PyPI

Uvicorn

A lightning-fast ASGI server for Python, built on uvloop and httptools.

10,993
BSD 3
Used by 83
91Health
Framework PyPI

FastAPI

A modern, high-performance Python web framework for building APIs with automatic validation, serialization, and interactive docs.

102,676
MIT
Used by 78
56Health
Tool npm

eslint-plugin-jsx-a11y

Static ESLint rules that catch JSX accessibility issues before code ships.

3,621
MIT
Used by 65
90Health
Tool PyPI

Ruff

An extremely fast Python linter and code formatter, written in Rust, built as a drop-in replacement for Flake8, Black, isort, and dozens of plugins.

49,811
MIT
Used by 46
95Health
Framework PyPI

aiohttp

Asynchronous HTTP client and server framework for Python's asyncio, covering both API calls and building web/WebSocket services.

16,561
Apache 2.0
Used by 40
95Health
Framework PyPI

Transformers

State-of-the-art pretrained models for text, vision, audio, and multimodal inference and training.

166,736
Apache 2.0
Used by 38
92Health
Framework npm

Docusaurus

React-based static site generator for building fast, maintainable documentation websites.

66,349
MIT
Used by 36
88Health
Tool PyPI

Gunicorn

A fast, lightweight pre-fork WSGI and ASGI HTTP server for running Python web apps in production on UNIX.

10,686
MIT
Used by 33
83Health
Tool PyPI

mypy

Optional static type checker that catches Python bugs before you run your code

20,651
MIT
Used by 30
81Health
Framework PyPI

Flask

A lightweight WSGI web framework for Python that scales from a single file to complex applications.

74,802
BSD 3
Used by 28
92Health
Framework npm

NestJS

A progressive Node.js framework for building efficient, scalable, and maintainable server-side applications in TypeScript.

76,743
MIT
Used by 27
89Health
Tool PyPI

Alembic

Database migrations tool for SQLAlchemy with autogenerate and transactional DDL

4,413
MIT
Used by 27
89Health
Framework PyPI

Typer

Typer is a Python library for building CLI applications, using type hints to generate arguments, options, validation, help text, and shell completion automatically.

20,033
MIT
Used by 26
91Health
Framework npm

Fastify

A fast and low-overhead web framework for Node.js, built around schema-based validation and a plugin architecture

37,205
MIT
Used by 25
87Health
Framework PyPI

Django

The high-level Python web framework that turns database models into secure, working web applications in record time.

91,218
BSD 3
Used by 24
83Health
Tool npm

svgo

A Node.js library and command-line tool that optimizes SVG files by removing redundant markup through a configurable plugin pipeline.

22,703
MIT
Used by 23
92Health
Framework PyPI

LangChain

The most widely adopted Python framework for building LLM-powered agents and applications

147,170
MIT
Used by 21
94Health
Framework PyPI

Starlette

A lightweight ASGI framework/toolkit for building async web services and apps in Python

12,639
BSD 3
Used by 21
93Health
Tool npm

nest-cli

Scaffolds, builds, and serves NestJS applications through schematics-driven code generation and pluggable compiler backends.

2,199
MIT
Used by 19
81Health
Tool PyPI

pytest-xdist

Distribute pytest test runs across multiple CPUs and hosts to cut suite runtime

1,908
MIT
Used by 19
92Health
Framework PyPI

LangGraph

A low-level orchestration framework for building stateful, multi-actor LLM agents as graphs

42,375
MIT
Used by 18

Join founders buildingwith open source

Opinionated takes, migration guides, cost-saving tips, and insights from the open source ecosystem.

Subscribe on Substack
Join 750+ subscribers