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

94Health
Tool npm

jest

Delightful JavaScript testing with zero-config setup, snapshots, mocking, and coverage

45,457
MIT
Used by 149
75Health
Library Cargo

serde_json

The de facto standard JSON library for Rust, built on the Serde serialization framework

5,636
Apache 2.0
Used by 111
82Health
Library PyPI

Requests

The elegant, human-friendly HTTP library that made Python's most-used API for talking to the web.

54,300
Apache 2.0
Used by 110
76Health
Library Cargo

serde

A generic framework for serializing and deserializing Rust data structures efficiently and safely.

10,825
Other
Used by 108
93Health
Library PyPI

Pydantic

Data validation and settings management using Python type hints, backed by a Rust core.

28,772
MIT
Used by 102
96Health
Framework PyPI

pytest

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

14,506
MIT
Used by 100
93Health
Framework Cargo

Tokio

The async runtime powering most of Rust's networked, concurrent, and I/O-bound applications.

33,150
MIT
Used by 95
54Health
Library PyPI

HTTPX

A next-generation HTTP client for Python with sync, async, and HTTP/2 support

15,478
BSD 3
Used by 85
91Health
Tool PyPI

Uvicorn

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

10,963
BSD 3
Used by 81
96Health
Library PyPI

NumPy

The fundamental N-dimensional array library powering Python's scientific computing stack.

32,741
BSD 3
Used by 80
55Health
Library PyPI

PyYAML

A full-featured YAML parser and emitter for Python, with C-accelerated bindings

2,942
MIT
Used by 79
90Health
Framework PyPI

FastAPI

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

102,333
MIT
Used by 76
65Health
Library PyPI

python-dotenv

Load environment variables from a .env file into Python's os.environ, the standard way to keep 12-factor config out of your code

8,876
BSD 3
Used by 72
84Health
Library Cargo

reqwest

An ergonomic, batteries-included HTTP client for Rust, with async and blocking APIs.

11,821
Other
Used by 70
73Health
Library Cargo

tempfile

A secure, cross-platform Rust library for temporary files and directories that clean up automatically on drop.

1,463
Other
Used by 68
67Health
Library Cargo

base64

Correct, fast, and configurable base64 encoding and decoding for Rust, with pluggable alphabets and padding.

736
Apache 2.0
Used by 66
98Health
Library PyPI

pandas

The Python DataFrame library for fast, flexible, and expressive data analysis and manipulation.

49,732
BSD 3
Used by 61
92Health
Library PyPI

Pillow

The friendly PIL fork that adds image processing capabilities to Python

13,812
Other
Used by 60
91Health
SDK PyPI

boto3

The official AWS SDK for Python — call every Amazon Web Services API from your code.

9,900
Apache 2.0
Used by 59
79Health
Library Cargo

regex

Rust's finite-automata regex engine with guaranteed linear-time matching and no catastrophic backtracking.

4,024
Apache 2.0
Used by 58
79Health
Library Cargo

Chrono

Timezone-aware date and time handling for Rust, with correct calendar operations and flexible strftime-style formatting.

3,907
Other
Used by 58
96Health
SDK PyPI

OpenAI Python SDK

The official Python library for the OpenAI REST API, generated from OpenAI's OpenAPI spec with typed sync and async clients.

31,622
Apache 2.0
Used by 57
90Health
Library Cargo

Clap

The most widely used command-line argument parser for Rust, with both derive and builder APIs.

16,707
Other
Used by 56
85Health
Library Cargo

uuid

Generate and parse UUIDs in Rust across every standardized version, from v1 to v8.

1,242
Other
Used by 56

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