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.
Manager.io
Full double-entry accounting on your own server: Manager.io Server Edition runs the same engine as the free desktop edition as a web server, so unlimited users work in unlimited businesses concurrently, with all books on infrastructure you control. The module coverage is genuinely comprehensive - general ledger with a customizable chart of accounts, sales and purchase invoices, quotes and orders, bank and cash account reconciliation, inventory with stock tracking, fixed assets with depreciation, payroll, multi-currency with exchange gains and losses, tax codes for VAT and GST regimes, and the complete reporting stack: balance sheet, profit and loss, trial balance, aged receivables and payables, and cash flow statements. The interface is translated into more than seventy languages, reflecting a genuinely global user base. The licensing model is the refreshing part: a server license is a one-time perpetual purchase, not a subscription - twelve months of updates included, optional renewals after, no per-user tiers, no data limits, and you can downgrade to the free desktop edition anytime, so your books are never hostage. Businesses wanting collaborative accounting behind their own firewall, with data sovereignty and no monthly fees, get exactly that.
Swetrix
Traffic analytics, real-user performance monitoring, and client-side error tracking - normally three tools - in one cookieless, privacy-first dashboard: Swetrix. The Community Edition ships the same core engine as the cloud product - a NestJS API with ClickHouse for high-volume event storage, MySQL for relational data, and Redis for caching, fronted by a React dashboard and a ~5 KB tracking script with official packages for 20+ frameworks including Next.js, WordPress, and Shopify. Traffic analytics cover pageviews, referrers, UTM campaigns, geolocation, sessions with page flows, funnels, and custom events - all anonymized server-side with no cookies, no cross-device tracking, and no consent banner required for GDPR compliance. Performance monitoring records real-user metrics per pageview: TTFB, DNS and TLS timing, and render times, so regressions surface in the same place as traffic. Error tracking captures unhandled JavaScript exceptions automatically with formatted stack traces, filename/line metadata, affected browsers and pages, first/last-seen timestamps, and a resolve workflow - replacing a separate error monitoring subscription for many teams. Alerts fire to email, Slack, Telegram, Discord, or webhooks on traffic spikes, new errors, and custom events. If Plausible covers your traffic questions but you also want to know why the site broke, Swetrix answers both.
DumbBudget
"Stupid simple software" is the entire philosophy at DumbWare.io, and DumbBudget delivers it: no over-engineering, no complexity, no accounts, no bank connections - just a clean, modern ledger for money in and money out. Log income and expenses, assign categories, and watch real-time balance calculations update as you type. Finding transactions is quick: filter by type, narrow by date range, sort by date or amount. When tax season or spreadsheet analysis calls, everything exports to CSV. Access control matches the philosophy - a single PIN (set via one environment variable) gates the app, backed by real security engineering: rate limiting on PIN attempts, temporary lockout after failures, secure session handling, and no sensitive data in browser storage. Multi-currency support covers the ISO codes, and a SITE_TITLE variable names each instance - deliberately useful, because running separate instances per account or family member is the intended pattern for multi-user needs. The responsive UI ships light and dark themes and installs as a PWA on phones, where expense logging actually happens. Configuration is five environment variables; data persists in one folder. If Actual Budget and Firefly III feel like accounting software, this is the notepad that gets used. GPL-licensed.
ExpenseOwl
Log a date, amount, and category; get a clean monthly pie chart and a cashflow strip showing income, expenses, and net balance - ExpenseOwl is expense tracking stripped to what actually matters. The MIT-licensed Go application deliberately is not a budgeting system - no envelopes, no accounts, no double-entry, no bank sync - because its author found tools like Firefly III and Actual too heavy for the simple question "where did this month's money go?" The dashboard makes that question fast: click a pie slice to exclude fixed costs like rent and see discretionary spending clearly, then drill into a chronological table view to inspect or delete individual transactions. Recurring transactions handle salaries and subscriptions automatically, optional tags add a second classification axis, and settings cover custom categories, currency symbol, and a configurable month start date for non-calendar pay cycles. CSV import migrates data from virtually any other tool, and CSV export keeps your data portable. It ships as a self-contained binary and multi-architecture Docker image with zero internet interaction, stores data in flat JSON files by default (PostgreSQL optional), and installs as a PWA on phones. Single-user by design; pair it with an authenticating reverse proxy if exposed publicly.
Tianji
Website analytics, uptime monitoring, and server status - three tools most teams run separately - combined in Tianji, an open-source observability platform. The analytics layer tracks page views, unique visitors, referrers, and UTM parameters with a lightweight cookie-less script, which keeps collection GDPR and CCPA friendly. The uptime monitor checks availability and latency on configurable intervals, accepts passively reported results, and publishes public status pages for incident communication. Server status agents report CPU, memory, disk, and network metrics with threshold-based alerts, and notifications route through webhooks, Slack, Telegram, and other channels with noise control. It also includes anonymous telemetry for tracking deployments of your own open-source projects, surveys, waitlists, team collaboration, and an OpenAPI interface for integrations and exports. The consolidation is the point: traffic analytics, uptime checks, and server metrics share one interface and one alerting layer, so diagnosing an incident does not mean hopping between Google Analytics, Uptime Kuma, and Prometheus - and the built-in public status pages replace a separate paid Statuspage-style subscription. Because collection uses no cookies with IP truncation and aggregation by default, basic traffic measurement requires no consent banner. Built in TypeScript under the Apache 2.0 license and inspired by Umami and Uptime Kuma, it is deliberately right-sized for independent developers and small SaaS teams whose monitoring needs are real but lightweight.
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.
The Lounge
"Forget about bouncers" became a real sentence because of The Lounge: a Node.js web IRC client that holds persistent connections to your networks 24/7, logging everything while you sleep, so closing the browser tab never means missing a message or losing your place in a channel. Open it again from any device - desktop, phone, tablet - and you resume exactly where you left off, with full history synchronized. Because it combines bouncer and client in one process, the experience feels like a modern chat app rather than 1990s infrastructure: push notifications for highlights and private messages (with self-generated VAPID keys, so even Web Push needs no third-party service), automatic link previews, inline file and image uploads, and full IRCv3 protocol support. It installs as a progressive web app from any modern browser, so phones get a native-feel client without an app store. Multi-user support means one instance serves your whole team or community, each user with their own networks and history, and LDAP integration ties into existing authentication. A public mode alternatively serves as an open, registration-free web chat for events or support channels. MIT-licensed, born as a fork of Shout, and a fixture of self-hosting stacks since.
Isso
Named from the German "Ich schrei sonst" - roughly "or I'll scream" - Isso is a lightweight Python/JavaScript commenting server, a drop-in Disqus replacement for people who noticed what Disqus does to reader privacy and page load times. The design premise is printed right in the docs: comments are not Big Data. So the backend is a single SQLite file rather than a database cluster, and the entire client is one embeddable JavaScript file - 65 kB, 20 kB gzipped - that you drop into any static site, blog, or CMS. Commenters write in Markdown, need no account, and can edit or delete their own comments within a configurable window (15 minutes by default). Spam control comes from an optional moderation queue: held comments stay invisible until you activate them via an admin interface or email notification links. Migration is a first-class feature, with importers for Disqus and WordPress exports, so years of existing threads move over intact. Because everything is server-rendered from your own instance, no third party tracks your readers, and real-world switchers report smaller pages and faster loads than the Disqus embed. MIT-licensed, running since 2012.
Corteza
Salesforce's platform model, 100% open-source (Apache 2.0): Corteza is a Go/Vue.js low-code platform developed under a foundation, so there is no open-core bait to grow out of. The heart is Corteza Compose: namespaces contain applications, modules define record structures the way Salesforce objects do, and a drag-and-drop page builder assembles record pages, list pages, dashboards, and charts from configurable blocks. Automation comes from a visual, BPMN-style workflow engine plus JavaScript automation scripts, so cross-application business logic - approval chains, field updates, notifications - is configured rather than programmed. Granular role-based permissions reach down to individual modules, fields, and records, mirroring real organizational hierarchies. Corteza CRM ships as the flagship application built entirely on Compose: leads, accounts, opportunities, campaigns, and cases with a 360-degree customer view, covering most Salesforce standard objects - and because it is just a Compose app, adding or reshaping modules is configuration, not a fork. Everything is reachable over REST APIs, deliberately familiar tooling eases Salesforce admin migration, and a CLI can even generate synthetic records for load-testing what you build.
LubeLogger
Vehicle maintenance records shouldn't live in a homemade spreadsheet and a shoebox of receipts - LubeLogger exists because of exactly that. It's a self-hosted .NET web application (from Hargata Softworks) that gives every vehicle in your garage a complete digital history: service, repair, and upgrade records categorized and searchable, with invoices and receipts attached as documents; fuel fill-ups that compute economy in MPG, UK MPG, L/100KM, or KM/L without spreadsheet tedium; taxes, odometer logs, inspections, equipment, and supplies inventory for tracking the parts and fluids on your shelf. The reminder system is what saves engines: recurring reminders trigger by date, odometer reading, or whichever comes first - exactly how real service intervals work - so oil changes and timing belts stop relying on memory. A dashboard summarizes expenses by year, month, and category, a planner tracks to-dos by type, priority, and progress, and professional vehicle reports print a full history - genuinely useful when selling a car. Collaboration is built in: invite household members as collaborators on shared vehicles, with single sign-on support. Custom fields adapt records to your needs, CSV import/export moves data freely, an API enables automation, and the mobile-tested UI installs as a PWA on iOS and Android. MIT-licensed.
HumHub
Workplace and Yammer's pattern on your own server, with GDPR compliance by construction rather than contract: HumHub is an open-source enterprise social network from Germany. Built in PHP on Yii2, it organizes everything around four concepts. Users get rich profiles with follows and interactions. Spaces are the structural unit - rooms for departments, projects, events, or clubs, with per-Space permissions, notification settings, and email summaries, and operators can auto-map users into the right Spaces. Content covers posts, wiki pages, photos and video, events, and tasks, with multi-level comments, versioning, archiving, moderation reporting, and filterable full-text search across everything. Modules make it a platform: roughly 80 install-and-activate extensions including Calendar, Wiki, Polls, Tasks, Gallery, News, direct-message Mail, OnlyOffice document editing, Advanced LDAP, SAML and JWT SSO, a RESTful API, mass user import, Translation Manager, and a Theme Builder with custom pages - every one optional and toggleable at runtime. That module economy is why HumHub serves such varied deployments: corporate intranets, city governments, universities, political parties, and nonprofits all configure the same core differently. Requirements are a plain LAMP stack - PHP 8.1+ and MySQL/MariaDB - making it one of the easiest community platforms to operate long-term.
Etherpad
In continuous open-source development since 2009, Etherpad is the original really-real-time collaborative editor - used by Wikimedia, governments, EU public-sector institutions, and tens of thousands of self-hosters. Its core idea is visible authorship: every keystroke is attributed with author colors, every revision preserved, and the timeslider lets you scrub through a document's entire history character by character. Multiple people type into the same pad and see each other's changes instantly - it scales to thousands of simultaneous editors per pad. The base install is deliberately lightweight; capability comes from roughly 290 plugins installable from the admin web UI: comments, images, tables, drawing, video chat via WebRTC, math rendering, code highlighting, and authentication via OAuth, LDAP, or OpenID. AI is pointedly a plugin, not a default - you choose the model and infrastructure, or never turn it on. There is no telemetry. For integrators, an HTTP API (with OpenAPI definitions at /api/openapi.json) manages pads, users, and groups for embedding in your own applications, and the ueberDB abstraction layer supports PostgreSQL, MySQL, Redis, MongoDB, and SQLite backends. Full data export is built in, the format is open, it is translated into 105 languages, and it runs on anything from a Raspberry Pi to a server farm. Apache 2.0 licensed, Node.js based.
Carbone
Document-generation code is the worst kind of code in your backlog - Carbone kills it. Its insight is separating design from data - templates are ordinary office documents (DOCX, ODT, XLSX, PPTX, HTML, even custom XML) built in LibreOffice, Microsoft Office, or Google Docs, with mustache-like markers such as {d.companyName} typed directly into the text. Send a template plus JSON from your existing APIs to the HTTP API, and Carbone returns the finished document - exported as-is or converted to PDF, XLSX, CSV, HTML, PNG, EPUB, and more via its integrated LibreOffice converter (Chromium and OnlyOffice engines are also supported for HTML-fidelity and office-format conversions). The template language goes well beyond substitution: loops over arrays render dynamic table rows, filters and aggregations run inside the document, and built-in formatters handle dates, numbers, currencies, timezones, and locales, with custom JavaScript formatters when needed. One template serves multiple languages through translation markers with auto-maintained translation files. The XML-agnostic engine means anything your document editor can design - pagination, headers, footers, nested tables, charts - survives generation intact, and Carbone guarantees no breaking changes in template syntax. Node.js-based, fast via multi-threaded LibreOffice conversion. The invoices, contracts, and reports your product owes its users become template edits, not sprints.
Countly
Mixpanel, OneSignal, and Crashlytics in one self-hosted stack - Countly is an all-in-one product analytics and engagement platform where every byte of first-party data stays on your server. A Node.js application over MongoDB, it collects through ten battle-tested SDKs spanning iOS, Android, web JavaScript, React Native, Flutter, Unity, and desktop (plus a data write API for anything else), and has powered tens of thousands of mobile, web, and desktop apps since 2012. The analytics core covers sessions, custom events, views, user profiles, and real-time dashboards, with exploration tools built for product managers as much as analysts. What separates Countly from pure analytics tools is acting on the data without third parties: built-in push notifications send automated, transactional, and personalized messages to iOS (APNs), Android (Firebase), and Huawei devices, with the SDK handling token retrieval and permission flows automatically; crash reporting captures symbolicated native crashes on iOS and Android plus JavaScript errors, correlated with the same user and session data. Email reports keep stakeholders updated, and the plugin-based architecture means features load as modules. For GDPR-sensitive products, engagement without piping user data to advertising companies is the entire point. AGPL-licensed server, installable in minutes.
Keila
Among open-source Mailchimp alternatives, Keila has the most modern UI - built in Germany on Elixir and Phoenix (the PETAL stack), with GDPR-conscious defaults including an optional no-tracking mode, and 100% open source with no proprietary premium tier. Campaign authoring is flexible three ways: a visual block editor with multi-column layouts, Markdown with or without WYSIWYG for hybrid HTML-plus-plain- text sends, and raw MJML for hand-coded designs. The personalization system is unusually clean - every contact carries custom data as a single JSON object (populated from sign-up form fields or pushed from your CMS/CRM), and Shopify's Liquid template language renders it into fully dynamic emails. Targeting uses a visual segment editor backed by a powerful segment language for complex logic over tags, language preferences, and any custom field. Sign-up forms with custom fields grow your lists; open and click tracking measures campaigns; scheduled sending handles timing. Delivery pipes through your own SMTP or first-class integrations with AWS SES (including automated bounce handling), SendGrid, Mailgun, and Postmark. A full REST API manages contacts, campaigns, and segments, with Erlang/OTP reliability underneath. Comfortable at 100K+ subscribers. AGPL-licensed, EU-hosted project, actively developed.
ClassicPress
WordPress without Gutenberg: ClassicPress, the community-led fork, keeps the TinyMCE classic editor as the default and strips the block editor and Full Site Editing out of core entirely. The result is roughly half WordPress's size - obsolete libraries like jQueryUI, Thickbox, and Flash support are gone, replaced by native HTML5 elements and modern alternatives like SortableJS - which translates to a measurably faster admin and a leaner attack surface. Forked from WordPress 6.2, it remains compatible with the vast plugin and theme ecosystem targeting that lineage (anything not requiring blocks generally works, helped by a blocks-compatibility mode), and the PHP-first WordPress API developers have used for over a decade works unchanged - no React required to extend your CMS. The fork adds its own improvements: built-in media categories and tags with bulk editing, revision management that lets you prune database bloat, native HTML5 dialogs for accessible touch-friendly menus, and recent releases bring APCu object-cache support, vanilla-JS core widgets, and performant translations. Governance is democratic and community-driven rather than corporate. For content sites, business sites, and blogs where the classic editing workflow is the feature, ClassicPress is stability as a philosophy.
KeeWeb
Your KeePass vaults, opened from any browser: KeeWeb reads, edits, and creates standard KDBX files, so it works with the same databases as KeePass and KeePassXC without conversion or lock-in. Self-hosting the web app gives you a password manager reachable from any modern browser, including mobile, with no client installation and no third-party cloud in the loop. All KDBX cryptography runs client-side; the server just serves the static app. Open multiple vault files simultaneously and search them all from one box, with advanced options covering specific fields, password history, and regular expressions. Vaults load from local files, your own server (WebDAV), or Dropbox, Google Drive, and OneDrive, with automatic sync - and files are cached for offline use, so a dropped connection never locks you out; changes resync once you're back online. Day-to-day niceties include a configurable password generator, protected fields that stay masked and are held in memory more defensively, entry history, tags with easy input, drag-and-drop attachments, and per-entry icons with favicon fetching. The optional KeeWeb Connect extension (Chrome, Firefox, Edge, Safari) autofills credentials using the keepassxc-protocol. MIT-licensed with matching desktop apps for macOS, Windows, and Linux.