Tiddlywiki
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.
Flatnotes
A web interface for a folder of Markdown files - Flatnotes is exactly that, and the discipline of that design is why people love it. Every note is a plain .md file in a single flat directory: no database, no proprietary format, no hierarchy to maintain, no export step if you ever leave. Edit notes in the browser or open the same files in VS Code or Obsidian, sync them with Syncthing or rsync while the app is running - the Whoosh-powered search index synchronizes incrementally, so external edits just show up. The interface is a clean Vue.js app with both WYSIWYG and raw Markdown editing modes (TOAST UI Editor), instant full-text search behind the "/" shortcut with partial-match support, wikilinks for cross-note references, and automatic tag extraction from #hashtags in note bodies. Light and dark themes and a mobile-responsive layout make it pleasant everywhere. Authentication is flexible for a personal tool: none, read-only, username/password, or TOTP two-factor. A documented REST API covers create/read/update/delete for automation. The operational story is the quiet selling point - the only state is the notes folder and a rebuildable index, so backup is copying a directory. For a personal notepad that respects your data, Flatnotes nails minimal.
Journiv
A Day One alternative that keeps your most personal writing on your own server: Journiv is journaling purpose-built for self-hosters. The FastAPI backend runs on SQLite by default with optional PostgreSQL, Redis, and Celery for background work, behind a clean, minimal web UI. Unlike general note-taking apps, it ships the features journaling actually needs: customizable moods and mood groups, activity tracking, goals with automated progress from logged activities, and daily writing prompts filterable by category and difficulty so a blank page never stalls you. Quick Log captures a moment in seconds and expands into a full entry later; "On This Day" resurfaces entries from past weeks, months, and years. Multiple journals separate work, gratitude, and personal writing, with tags and full-text search across everything, plus media uploads with automatic thumbnails and an Immich integration for linking photo-library memories. Analytics chart mood trends and writing patterns over time. Data portability is taken seriously: native import of Day One exports, JSON/Markdown/HTML export, and a standalone HTML viewer that opens your archive in any browser with no server running. OIDC single sign-on works with Authentik or Keycloak, and multi-arch images cover amd64 and arm64.