Directory

Free, moderated open-access preprint server for physics, mathematics, computer science, statistics, quantitative finance, economics and related fields, with an open API and bulk access

Open-source, offline-first API client that stores collections as plain-text .bru files in a Git repository, with a CLI for running requests in CI

Québec's shared open-data portal where provincial ministries and municipalities publish datasets under a Creative Commons Attribution licence

Minimal, unopinionated web framework for Node.js with routing and middleware, the long-standing default for HTTP servers in the Node ecosystem

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

Small TypeScript web framework built on Web Standard APIs that runs unchanged on Cloudflare Workers, Deno, Bun, Node.js and other JavaScript runtimes

Open-source API client that runs in the browser or as a desktop app, supports REST, GraphQL and realtime protocols, and can be self-hosted for teams

C/C++ inference engine for LLMs and vision-language models with GGUF quantized weights, Metal, CUDA, Vulkan and other backends, a CLI and an OpenAI-compatible server

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

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

Vendor-neutral, machine-readable standard for describing HTTP APIs in JSON or YAML, maintained by the OpenAPI Initiative under the Linux Foundation

Non-profit registry of persistent researcher identifiers (ORCID iDs) with user-controlled records, Public and Member APIs, OAuth sign-in and an annual CC0 public data file

Free, open-source research management platform from the Center for Open Science for projects, preregistrations, registries, preprint services and linking outputs across storage providers

Read-only query service for OpenStreetMap data using the Overpass QL language, available on public instances or self-hosted

Python data-validation library using type hints to parse, validate and serialize models, with a Rust core; the schema layer behind FastAPI and many LLM SDKs

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

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

GPL-licensed in-memory search engine in C++ offering typo-tolerant instant search, faceting, vector and hybrid search, with Typesense Cloud hosting

High-throughput LLM inference and serving engine with PagedAttention, continuous batching, quantization and an OpenAI-compatible server for GPU and accelerator clusters

Free general-purpose research repository operated by CERN that assigns DOIs to datasets, software, papers and other outputs, with a REST API, OAI-PMH, GitHub release archiving and CC0 metadata