Directory

Python workflow orchestration library and server where decorated functions become observable, retryable flows, with Prefect Cloud as hosted option

Opinionated code formatter for JavaScript, TypeScript, CSS, HTML, Markdown, YAML and more that reprints code from its syntax tree with few options

TypeScript ORM with a declarative schema language, generated type-safe client and migration tooling, from the company that also offers Prisma Postgres and related hosted services

Open-source computational notebook ecosystem: the .ipynb format, kernels for Python, R and Julia, JupyterLab and Notebook interfaces and JupyterHub

Open-source, local-first CLI and library for evaluating prompts, models, RAG pipelines and agents, with automated red teaming and CI integration

Python testing framework with plain assert statements, fixtures, parametrization and a large plugin ecosystem, the de facto standard for Python test suites

General-purpose, dynamically typed programming language with a large standard library and the dominant ecosystem for data science and machine learning

Open-source deep-learning framework with eager tensors, autograd, torch.compile and distributed training, governed by the PyTorch Foundation and the base of most LLM tooling

Open-source vector search engine written in Rust with filterable HNSW indexes, sparse and multi-vector support, REST/gRPC APIs and a managed cloud

Algorithmic trading platform built on the open-source LEAN engine, with cloud backtesting, research notebooks and brokerage-connected live trading

Open-source message broker in Erlang supporting AMQP 0-9-1 and 1.0, MQTT, STOMP and Streams, with routing, acknowledgements and quorum queues

Open-source Python framework for distributing tasks, actors and ML workloads across a cluster, with libraries for data processing, training, tuning, serving and reinforcement learning

Component-based JavaScript library for building user interfaces, created at Meta, with hooks, a declarative rendering model and server components

Mature open-source Python framework for writing crawlers (spiders) that fetch pages asynchronously, extract structured items and export them through pipelines

Static analysis engine that matches code patterns written in the target language's own syntax, with an LGPL community edition and a commercial AppSec platform

Python documentation generator using reStructuredText or MyST Markdown with cross-referencing, API autodoc and output to HTML, PDF via LaTeX, ePub and man pages

Open-source backend platform built around a dedicated PostgreSQL database with auto-generated APIs, authentication, file storage, realtime subscriptions and edge functions

Utility-first CSS framework from Tailwind Labs that styles markup with composable class names and generates only the CSS a project uses

Distributed SQL query engine that federates queries across data lakes, warehouses and databases through connectors, formerly PrestoSQL

Build system for JavaScript and TypeScript monorepos from Vercel that runs package tasks in dependency order with local and remote caching

Statically typed superset of JavaScript from Microsoft that compiles to plain JavaScript and powers editor tooling across the web ecosystem

Markup-based typesetting system with an Apache-2.0 compiler written in Rust and a collaborative web app, positioned as a faster, simpler alternative to LaTeX

Free, extensible code editor from Microsoft with a large extension marketplace, integrated terminal, debugging, remote development and built-in AI assistance

Front-end build tool and development server that serves native ES modules during development and bundles for production, with a plugin API shared by many frameworks