Directory

Apple's built-in notes app for Mac, iPhone, iPad and iCloud.com with folders, tags, attachments, handwriting, shared notes and on-device search

Modular JavaScript library for bespoke, data-driven web graphics: scales, axes, shapes, layouts, geo projections, transitions and DOM selections

Free diagramming editor (formerly diagrams.net) for flowcharts, network, UML and architecture diagrams, available as web app, desktop app and integrations

Open-source virtual whiteboard for hand-drawn-style diagrams with live collaboration, embeddable as a React component, plus a hosted Excalidraw+ service

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

Lightweight open-source JavaScript library for interactive tile-based web maps with markers, vector layers and a large plugin ecosystem

Open-source vector-tile map renderers for web (GL JS) and native platforms, forked from Mapbox GL and governed by a community organisation

Reactive Python notebook stored as a plain .py file that re-runs dependent cells automatically and doubles as a script or web app

Free reference manager from Elsevier with a desktop and web app, PDF annotation, a Web Importer, groups and bundled cloud storage

JavaScript library that renders flowcharts, sequence, class, state, ER, Gantt and other diagrams from a Markdown-like text syntax

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

MIT-licensed interactive charting libraries for Python (plotly.py), JavaScript (plotly.js) and R, plus the Dash framework for analytical web apps

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

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

Posit's open-source integrated development environment for R, with console, editor, plots, environment panes, Quarto/R Markdown authoring and Python via reticulate

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

Free, open-source reference manager with browser connectors, word-processor plugins, a PDF reader, group libraries and optional paid file storage