A self-hosted "second brain": Khoj indexes your own files and answers questions from them, parsing Markdown (whole Obsidian vaults included), org-mode, PDF, Word, plain text, Notion pages, GitHub repositories, and images described by a vision model, then embedding everything with sentence-transformers into a vector index for semantic search and RAG with cited sources. Any LLM backend works: local models like Llama, Qwen, or Mistral via Ollama, or cloud models like GPT, Claude, and Gemini. You can build custom agents, each with its own persona, scoped knowledge base, chat model, and tools such as web search and code execution. Scheduled automations run recurring research and deliver newsletters or notifications to your inbox, and research mode performs multi-hop web searches with inline citations. Access it from a browser, the Obsidian plugin, Emacs, desktop, or WhatsApp - all clients connect to the same self-hosted instance, making Khoj one of the few AI assistants Emacs users can point at decades of org files. Semantic search means recall works without exact keywords: "that paper about forecasting with transformers" surfaces the right PDF even when you cannot remember its title. Switching LLM backends never requires re-indexing your documents, and with a local model via Ollama, even inference stays on hardware you control - journals, research, and private notes are never sent anywhere. Python/FastAPI stack, AGPL-licensed, with PostgreSQL storage.

Open the page, write a Markdown note, move on - Memos is a lightweight, self-hosted service built for quick capture. Instead of folders, notebooks, and titles, it presents a timeline: open the page, write a Markdown note, and move on. Notes support headings, code blocks with syntax highlighting, task lists, tables, and file attachments, with tags auto-extracted from #hashtags in the text. Each memo carries a visibility level, private, protected (logged-in users), or public, so one instance works as a personal log, a small team wiki, or a lightweight microblog. The backend is a single Go binary with a React frontend, around 50 MB of memory at runtime and a ~20 MB Docker image, so it fits comfortably on the smallest instance size with near-zero maintenance. SQLite is the default store, with MySQL and PostgreSQL supported for multi-user deployments needing more concurrency, and full REST and gRPC APIs - Connect RPC for browsers, gRPC-Gateway for external tools - make capture scriptable from CLIs, bots, and automation platforms. Fast full-text search spans all memos, pinned notes keep references handy, and a masonry view suits visual browsing. MIT-licensed with zero telemetry; content is stored as plain Markdown in a database you control, so notes remain readable, exportable, and free of proprietary formats.

For people whose notes number in the tens of thousands, Trilium Notes is the hierarchical note-taking application built specifically for large personal knowledge bases - actively maintained as TriliumNext. Notes arrange into arbitrarily deep trees where every note is both content and container, and cloning lets a single note live in multiple places at once - bash notes belong under both Linux and Scripting, and Trilium refuses to make you choose. A WYSIWYG editor handles rich text, tables, math, and syntax-highlighted code blocks with Markdown-style shortcuts, while dedicated note types cover Excalidraw sketches, mind maps, geo maps with GPX tracks, relation maps that visualize connections between notes, and tables with typed columns. The attribute system is the power layer: labels attach queryable metadata (#year=1999, #author), relations create named links between notes, and both inherit down the tree - feeding full-text search, saved queries, and scripting. Scripting is Trilium's deepest differentiator: JavaScript code notes run on events like note changes or hourly schedules, build custom widgets, and add server-side logic, turning the knowledge base into a programmable platform. Protected notes encrypt sensitive content, note hoisting focuses on subtrees, and the self-hosted server syncs desktop clients across devices.

Confluence and Notion both want your team's documentation in their cloud; Docmost, an open-source collaborative wiki platform, keeps it on your server. The centerpiece is a Notion-style block editor with CRDT-based real-time collaboration: multiple people edit the same page simultaneously and changes merge without conflicts or overwrites. Content lives in spaces - per team, project, or department - with nested page trees, role-based permissions, groups, inline comments, page history with restore, and full-text search across everything. The editor covers tables, code blocks, callouts, KaTeX math, and file attachments, and diagramming is built in rather than bolted on: Mermaid, Draw.io, and Excalidraw all render inside pages, alongside embeds for Airtable, Loom, Miro, and more. Migration paths include Notion, Markdown, HTML, and ZIP archive imports (Confluence, PDF, and DOCX importers ship in the Enterprise edition, along with SSO via SAML/OIDC/LDAP and MFA). The stack is TypeScript with PostgreSQL and Redis, deploys via Docker Compose, runs in air-gapped environments with no external dependencies, and is translated into 10+ languages. The AGPL-3.0 community edition carries no per-seat fees; the project has passed 20,000 GitHub stars since its 2024 launch.

Memos, the lightweight open-source note service from the usememos project, packaged as a containerized deployment for multi-architecture Docker hosts (x86-64 and arm64): that is Usermemos. The model is frictionless capture: no folders or titles, just a chronological stream of Markdown notes with code blocks, task lists, tables, and file attachments, organized by #hashtags pulled automatically from the text. Per-memo visibility - private, protected for logged-in users, or public - lets a single instance serve as a personal journal, a shared team log, or a public microblog simultaneously. Multi-user support with authentication makes it workable for small teams, and full REST and gRPC APIs open capture and retrieval to CLIs, bots, and automation tools. The runtime is a single Go binary with a React frontend that idles around 50 MB of memory and stores content as plain Markdown in SQLite by default, with MySQL and PostgreSQL available for heavier deployments. Configuration happens through environment variables, access works over HTTP or HTTPS behind a reverse proxy, and there is no telemetry - notes stay on your server in a portable format.

Notes on Windows, macOS, Linux, Android, iOS, and the terminal, synced through your own server: Joplin pairs its open-source clients with Joplin Server, the official self-hosted backend that replaces Dropbox, OneDrive, or Nextcloud as the synchronization target. Notes are Markdown with inline attachments (images, PDFs, audio), organized into hierarchical notebooks and sub-notebooks with cross-cutting tags, alongside to-do lists with reminders and alarms. End-to-end encryption is the headline feature: enabled in the clients, it encrypts sync payloads on-device before upload, so the server stores blobs it cannot read - genuine protection even if the host is compromised. The desktop app offers both Rich Text and Markdown editors, extended by a plugin ecosystem, custom themes, and an Extension API for writing your own scripts; a Web Clipper for Chrome and Firefox captures full pages or screenshots straight into notebooks. Joplin Server ships as a Docker image with SQLite for evaluation and PostgreSQL for production, offers a filesystem storage driver for large content, and includes multi-user support and note sharing - all free under AGPL-3.0 when self-hosted. Notes stay in an open format, so the exit path always exists.

Every line an indentable bullet, every bullet a first-class block that can be referenced, embedded, and queried anywhere: Logseq is a privacy-first, local-first knowledge platform built around the block outliner. The daily journal is the system's beating heart - each day opens a fresh date-stamped page where tasks, meeting notes, and fleeting ideas land as blocks without filing decisions, then connect later through [[wikilinks]] with automatic bidirectional backlinks and ((block references)) that transclude any bullet into any page. Everything persists as plain Markdown or Org-mode files on disk - git-friendly, greppable, and owned forever, with sync via iCloud, Dropbox, Syncthing, Git, or an optional end-to-end encrypted service. Built-in tooling goes beyond notes: TODO/DOING task states with scheduling, native PDF annotation with area highlights, spaced-repetition flashcards, whiteboards for visual thinking, Zotero integration for researchers, and Datalog-powered queries that build dynamic views across the entire graph. A marketplace of hundreds of community plugins and themes adds AI chat, Ollama local-model integration, and custom workflows. Written in Clojure/ClojureScript, AGPL-3.0 licensed with 320+ contributors, and completely free - the local-first Roam for people who refuse subscriptions and lock-in.

Links rot - the hard truth Linkwarden is built around, as a collaborative bookmark manager that preserves what it saves. Every page you save is fully preserved - a screenshot, a PDF, a self-contained single-file HTML archive (generated by the Monolith Rust binary), and a clean reader view - so the content survives even after the original site disappears. Think of it as a private Wayback Machine you own, with an optional one-click snapshot to archive.org on top. The reading experience matches the archival rigor: a distraction- free reader view supports text highlighting and annotation, and full-text search across everything you have saved is powered by Meilisearch. Optional AI tagging analyzes page content and auto-assigns tags - generate new ones, pick from your existing set, or constrain to predefined tags - with providers ranging from local Ollama models (fully private) to OpenAI, Anthropic, and OpenRouter. Organization is collections, sub-collections, and multiple tags per link; teams collaborate on shared collections with per-member permissions, and public collections share curated link sets (with preserved copies) to anyone. The stack is Next.js/React on TypeScript with PostgreSQL via Prisma, NextAuth supporting credentials, OAuth2, and SAML SSO, and a Playwright-driven headless Chromium worker doing the capture. Native iOS and Android apps and browser extensions feed it from anywhere.

The entire wiki - content, code, and interface - is built from "tiddlers," small addressable units of information that link, transclude, tag, and filter into each other: TiddlyWiki is a non-linear personal notebook with a design philosophy unlike anything else in this catalog. Instead of pages in a hierarchy, you compose views by pulling tiddlers together on demand, which is why researchers, zettelkasten practitioners, and GTD devotees have sworn by it for two decades. The whole application is JavaScript, and the UI itself is written in hackable WikiText - customization goes as deep as rewriting the interface from inside the wiki. Self-hosting runs the Node.js version, which upgrades the classic single-HTML-file architecture in the ways that matter for a server: every tiddler is stored as an individual text file (Git-friendly, organizable), edits save through the HTTP API from any modern browser including phones, and one installation can serve multiple wikis blending shared and unique content. The plugin ecosystem covers graph visualizations, themes, languages, and hundreds of community extensions, declared per-wiki in a simple tiddlywiki.info file; the newer MultiWikiServer plugin adds multi-user accounts and tiddler sharing. Your notes stay usable for decades, independent of any corporation - the project's founding promise. BSD-licensed.

Large link collections stay fast and organized in Faved, a private, self-hosted bookmark manager built for exactly that job. Its core is a nested tagging system that outgrows flat folders: place Go and Python under Programming Languages, color-code tags, add descriptions, pin frequent ones to the top of the sidebar, and optionally roll up child-tag items into parent views. Saving is frictionless - a lightweight bookmarklet works in any desktop or mobile browser without extensions, and Apple devices can send links through the native Share menu. Faved fetches titles, descriptions, and preview images automatically, keeps that metadata fresh over time, and flags duplicates as you save. Instant as-you-type search, flexible sorting, and bulk actions (retag, delete, refetch) keep collections of any size manageable, while customizable layouts - card, list, or table - plus a system-synced dark mode adapt the interface to your workflow. Migration is first-class: import from Chrome, Safari, Firefox, or Edge with folder structure preserved, or move from Pocket and Raindrop.io keeping tags and collections. The stack is deliberately light - PHP 8 with SQLite behind a React/Tailwind frontend - deploying via Docker with no external dependencies. All data stays local: no ads, no tracking, and no risk of your library vanishing with a discontinued service.

Enterprise documentation discipline without enterprise infrastructure: Documize Community is the Confluence alternative built on exactly that trade. The entire platform - Go backend, Ember.js frontend - compiles to a single executable binary for Linux, Windows, and macOS with zero runtime dependencies: no Elasticsearch, no Redis, no JVM. Point it at PostgreSQL, MySQL, MariaDB, Percona, or Microsoft SQL Server (rare in open source, decisive in Microsoft shops), and schema migrations run on launch with native full-text search on whichever engine you chose. Content organization rejects nested-folder sprawl for Spaces, categories, and labels, and the section-based composable editor mixes rich text, Markdown, code blocks, PDFs, diagrams, and embedded Jira or Trello content in one document, with reusable blocks and templates so teams start from standards rather than blank pages. It deliberately unifies internal team docs and customer-facing documentation in one system with granular space-, document-, and action-level permissions deciding who sees what. Where wikis stop, Documize continues: content approval workflows (draft, review, approve, publish), version management, lifecycle control, feedback capture, PDF export, analytics showing what gets read and ignored, activity streams, and audit logs. Keycloak, LDAP, and SSO integrate for enterprise auth. AGPL-licensed.

A federated bookmark manager written in Rust: Ties (formerly linkblocks) is your own small corner of the web for saving, organizing, and sharing good pages, connected to the fediverse over ActivityPub. Instead of rigid folders, bookmarks live in arbitrarily nested lists that link together into a knowledge graph. Saved pages are fetched, converted to a readable archived version, and stored in the database, so full-text search covers titles, URLs, and the actual page text - and the content survives if the original disappears. The federation model is deliberately anti-viral: there is no global timeline and no algorithmic feed. You publish public lists for anyone, follow users whose taste you trust, and mark trusted users whose bookmarks become part of your search range - extendable to trusted-users-of-trusted-users for a wider net. Public bookmarks post to Mastodon timelines, and WebFinger lookup makes your handle discoverable across fediverse platforms. Operationally it is about as light as web software gets: a single binary with all assets baked in, integrated TLS so it can run without a reverse proxy, PostgreSQL as the only dependency, OIDC single sign-on, and a bookmarklet for one-click saves. Note the project is alpha: single-user instances only, and all data should be considered public. AGPL-3.0 licensed, built with Rust and htmx.

Personal, minimalist, database-free bookmarking - Shaarli is a philosophy as much as an app. Everything lives in a single compressed datastore file inside data/: no MySQL, no PostgreSQL, backup by copying one directory. That write-once/read-many file is usually served straight from OS disk caches, which is why a decade-old Shaarli instance with tens of thousands of links still responds instantly. Designed deliberately single-user, it saves URL, title, unlimited-length description, and tags (with autocomplete, renaming, and merging), marks entries public or private, and automatically strips utm_source and fb tracking parameters from saved URLs. That description field is why the community uses Shaarli as far more than bookmarks: a microblog, read-it-later queue, code-snippet base, pastebin, and shared clipboard between machines. Sharing is one click via bookmarklet or Android apps; consumption is per-tag RSS/Atom feeds plus a daily digest feed; search is full-text with tag filtering. A REST API opens it to any client, a plugin and theme system extends the PHP core (Markdown rendering, thumbnails), and import/export uses browser-standard Netscape HTML - your data enters and leaves freely. LDAP login is supported, no telemetry is sent anywhere, and the UI degrades gracefully without JavaScript. The anti-cloud Delicious.