Directory

Distributed event streaming platform with durable, partitioned, replayable logs, Kafka Connect connectors and Kafka Streams processing

Open-source columnar OLAP database server for fast aggregations over billions of rows, with MergeTree storage, SQL and a managed ClickHouse Cloud

Distributed search and analytics engine on Apache Lucene with full-text, aggregations, vector search and ES|QL; triple-licensed AGPL, SSPL and Elastic License

Python web framework for building HTTP APIs from type-annotated functions, with automatic validation through Pydantic and generated OpenAPI documentation

Free economic database from the St. Louis Fed aggregating hundreds of thousands of US and international time series, with graphs, vintages (ALFRED), an Excel add-in and a keyed JSON/XML API

Lightweight self-hosted Git forge written in Go with repositories, pull requests, issues, packages and GitHub-compatible Actions, deployable as a single binary

Open-source system for scheduling, scaling and operating containerized workloads across a cluster of machines

Low-level orchestration framework and runtime for stateful, long-running agents expressed as graphs, with durable execution, checkpointing, human-in-the-loop and streaming

Nonprofit certificate authority that issues free, automatically renewable TLS certificates through the ACME protocol

Open JSON-RPC standard for connecting AI applications to tools, data and prompts through servers, now stewarded under the Linux Foundation with SDKs in many languages

React framework from Vercel for full-stack web applications with file-based routing, server components, server-side rendering, static generation and API route handlers

Server-side JavaScript runtime built on the V8 engine, governed by the OpenJS Foundation, with npm as its package ecosystem

Local-first Markdown note-taking app with bidirectional links, graph view and a large community plugin ecosystem; optional paid Sync and Publish

Open-source runtime and model manager for running open-weight LLMs locally on macOS, Windows and Linux, with a REST API, OpenAI- and Anthropic-compatible endpoints and optional cloud models

Open catalog of the global research system: works, authors, sources, institutions and topics under CC0, served by a REST API, web app and S3 snapshot

Collaboratively edited world map database released under the ODbL, with planet files, an editing API and derived tiles and extracts

PostgreSQL extension adding vector types, distance operators and HNSW/IVFFlat indexes for similarity search inside the database

Microsoft's browser automation and end-to-end testing framework driving Chromium, Firefox and WebKit from one API in TypeScript, Python, Java and .NET

Rust-based DataFrame library with Python, Rust, Node and R bindings offering lazy query optimization, multithreading and Arrow-native memory

Spatial extension for PostgreSQL adding geometry, geography and raster types with indexing and hundreds of SQL functions

Open-source object-relational database server with a large extension ecosystem (PostGIS, pgvector, TimescaleDB) and broad SQL coverage

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

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

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