Open Source App Cloud Marketplace

Built for self-hosting from the ground up, Kutt is a modern, MIT-licensed URL shortener: zero-configuration setup, no build step, and SQLite, PostgreSQL, or MySQL with optional Redis caching. Links carry real management features - custom slugs from a configurable alphabet (confusable characters like 0/O and l/1 omitted by default), password protection, descriptions, expiration times, and the ability to edit a destination URL without changing the short link already in circulation. Custom domains make branded short links first-class: add as many as you like and serve each under your own name instead of a third-party's. Private, per-link statistics track clicks, browsers, operating systems, and countries without logging visitor IPs or sensitive data. An admin page manages users and links instance-wide, and two environment flags (DISALLOW_REGISTRATION, DISALLOW_ANONYMOUS_LINKS) lock the instance down for private use; OpenID Connect login integrates with an existing identity provider. Automation runs through a documented REST API - create, list, delete, and pull stats - plus Chrome and Firefox extensions and ShareX compatibility for shortening from anywhere. Built with Node.js and React, deployed in one Docker container, it replaces Bitly with something you own: your domain, your analytics, and links that never die with a vendor.

Send a document, receive a PDF: Gotenberg is a Docker-based, stateless HTTP conversion API trusted in production by thousands of companies and adopted by notable open-source projects. Send files as multipart/form-data, get a PDF back; Chromium, LibreOffice, and fonts are the container's problem, not yours. Headless Chromium handles URLs, HTML templates, and Markdown with pixel-perfect browser rendering: it executes JavaScript, loads web fonts, waits for network idle, a JS expression, or a DOM selector before rendering SPAs, and accepts injected cookies and HTTP headers for authenticated pages. LibreOffice converts 100+ office formats - .docx, .xlsx, .pptx, and legacy formats - with page-range extraction and PDF/A archival conformance. Built-in PDF engines round out the pipeline in every image variant: merge, split, rotate, flatten, encrypt, watermark, stamp, read/write metadata and bookmarks, plus Factur-X/ZUGFeRD e-invoicing and PDF/UA accessibility compliance. Screenshots of URLs and HTML come from the same endpoints. Zero-transfer pipelines stream files directly between S3, MinIO, or GCS presigned URLs and Gotenberg, bypassing your application entirely, and webhooks enable async processing. Statelessness means horizontal scaling is trivial - run as many replicas as your conversion volume demands. Three image variants (full, Chromium-only, LibreOffice-only) trim the footprint to what you actually use.

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.

Deployment decoupled from release: Unleash, the most popular open-source feature management platform on GitHub, is a Node.js server backed by PostgreSQL. Ship code dark, then control who sees it through activation strategies: gradual percentage rollouts, targeting by user ID, IP, hostname, or application name, custom constraints against your own context fields, and scheduled or time-limited releases. Strategies stack - a flag activates if any strategy matches - and strategy variants layer A/B versions on top of the on/off decision. Each flag carries per-environment configurations, so a feature can run at 100% in staging while canarying at 5% in production. Backend SDKs (Node.js, Java, Go, Python, Ruby, .NET, PHP, Rust, and more) fetch configuration and evaluate flags locally, so a flag check adds zero network latency to request paths; frontend SDKs for React, Vue, Svelte, iOS, Android, and Flutter evaluate through a proxy layer. Flag hygiene is built in: flags are typed (release, experiment, operational, kill-switch, permission) with expected lifetimes, and Unleash marks overdue flags as potentially stale and surfaces unknown flags your SDKs request but that don't exist. Self-hosting via Docker keeps flag data, targeting rules, and evaluation infrastructure entirely on your side.

Securing a SaaS product, running B2B onboarding, or replacing Auth0 and Keycloak with a stack they own - teams needing more than basic auth reach for ZITADEL, an open-source identity and access management platform built in Go. Its multi-tenancy model is the differentiator: a strict Instance, Organization, Project hierarchy isolates data and scopes policy at each level, with identity brokering (pre-built templates for Google, GitHub, Microsoft, Apple, plus generic OIDC, OAuth, SAML, and LDAP), domain discovery that routes users to the right organization by email domain, and delegated management so customers administer their own users and roles. Authentication covers OpenID Connect (certified, including device authorization and token exchange), SAML 2.0 as both IdP and SP, SCIM, FIDO2 passkeys for phishing-resistant passwordless login, and MFA via OTP, email, SMS, and U2F; machine-to-machine flows support JWT profile, PATs, and client credentials. The architecture is event-sourced - every mutation is an immutable event, yielding a complete audit trail - with relational projections for queries and no external session store, so it scales horizontally. API-first with gRPC and REST, extensible via Actions webhooks, and the same codebase self-hosted (Docker Compose or Helm on PostgreSQL) as in the cloud.

Real-time collaborative Markdown behind your own firewall: HedgeDoc (formerly CodiMD, descended from HackMD's open-source edition) keeps team notes on team infrastructure. Share a note's URL and collaborators are editing together instantly - live cursors, changes appearing keystroke by keystroke - in a three-mode interface that toggles between raw Markdown, rendered preview, and side-by-side split. The Markdown dialect is extended where engineers need it: Mermaid, Graphviz, and Vega-Lite diagrams, MathJax for equations, syntax-highlighted code blocks, embedded content, and a presentation mode that turns a note into reveal.js slides with a single YAML header. A dropdown permission system controls each note - freely editable, limited to signed-in users, or locked read-only - and published notes become clean read-only pages for wider distribution. Revisions track every change with the ability to revert to any earlier version. The AGPL-3.0 codebase is light enough to run on a Raspberry Pi and deploys via Docker with PostgreSQL, MySQL, or SQLite. Authentication covers LDAP, SAML, OAuth2, and email. It deliberately stays a focused document editor - no page trees or kanban - and does that one job with excellent keyboard-first ergonomics for meeting notes, RFCs, runbooks, and shared scratchpads.

Real LibreOffice document engineering in the browser: Collabora Online is built by the company employing much of the former SUSE LibreOffice team - not a reimplementation. This deployment runs CODE (Collabora Online Development Edition), the collabora/code server that renders and edits documents entirely server-side while browsers get high-fidelity WYSIWYG output, so layout and formatting survive round-trips that break lesser converters. Four editors ship in one container: Writer for text documents (comments, track changes with comparison and restoration, form handling), Calc for spreadsheets (advanced formulas, macros, pivot tables, per-user sheet views, server-enforced cell protection), Impress for presentations, and Draw for Visio-class diagrams. Format compatibility spans DOCX, XLSX, PPTX, the ODF family, PDF, and dozens more - including Visio and Publisher import. Real-time collaborative editing supports multiple simultaneous editors with visible cursors and commenting. The architectural point: documents are processed on your server and never leave it, which is why Collabora is the engine behind Nextcloud Office and integrates with ownCloud, Seafile, and any WOPI-speaking host - or embeds in your own application via the SDK. An admin console monitors sessions and memory. For organizations that need Google Docs-style collaboration with actual data sovereignty, this is the reference open-source answer.

Matrix's flagship client, built by the protocol's creators: Element brings the decentralized open standard for real-time communication to web, desktop, iOS, and Android. Paired with a Matrix homeserver, it delivers Slack-quality team messaging where you own every message, file, encryption key, and byte of metadata. End-to-end encryption is on by default, built on Olm and Megolm - the Double Ratchet algorithm family Signal popularized, extended for large-room scalability and publicly audited by NCC Group. Messages encrypt per-device with cross-signed device verification, so even a compromised server yields nothing readable. Federation is the defining capability: like email, users on different homeservers converse seamlessly, and 30+ bridges connect Matrix rooms to Slack, Discord, WhatsApp, and Telegram, so moving to sovereign infrastructure doesn't sever contact with anyone. Rooms support threads, reactions, file sharing, and voice and video calls via Element Call. The result is digital sovereignty chosen by governments and enterprises across Europe: your data sits on your server in your jurisdiction, portable to any other Matrix host because the protocol is an open standard. Apache-2.0 licensed, with no per-user fees at any scale.

Browse trending titles, search anything, request it in two clicks: Jellyseerr gives Jellyfin, Emby, and Plex users a beautiful storefront for the media library. Born as the Overseerr fork that added Jellyfin and Emby support (the projects have since unified as Seerr), it handles the full request lifecycle - users authenticate with their existing media-server accounts, pick individual seasons or movies in a clean interface, and admins approve or decline from a simple queue, including on mobile. Approved requests flow straight to Sonarr and Radarr, which handle acquisition automatically, with support for separate 4K server instances. Regular library scans keep availability accurate, so users see instantly what already exists instead of requesting duplicates. A granular permission system controls who can request what - auto-approval for trusted users, quotas and limits elsewhere - and override rules adjust request routing by user, tag, or other conditions. Watchlist and blocklist functions curate discovery, notifications reach email, Discord, Telegram, Slack, Pushover, and Pushbullet, and both PostgreSQL and SQLite are supported. Localized into many languages, it turns "can you add this movie?" texts into a self-service system that runs itself.

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.

Fifty-plus image processing tools in a single Docker container, with no Redis, no Postgres, and no external dependencies: SnapOtter is a self-hosted image toolkit. The everyday operations are all here: resize, crop, compress, watermark, vectorize, meme generation, GIF creation, and format conversion spanning 55+ input formats (including 23 camera RAW formats) to 14 output formats. What sets it apart is the local AI layer: background removal, photo upscaling and restoration, object erasing, face blurring, OCR, and canvas expansion all run on locally hosted models, so no image ever leaves your server - a hard guarantee that cloud tools like remove.bg or Canva can't make. Optional NVIDIA GPU support accelerates those AI tasks substantially when hardware is available, but everything works on CPU. A built-in layer-based editor handles composition work directly in the browser, and screenshot beautification turns plain captures into polished visuals with backgrounds, shadows, and padding - useful for docs and marketing alike. Batch operations process unlimited images simultaneously, and the full REST API with OpenAPI documentation exposes every tool for pipelines and automations: thumbnail generation on upload, bulk RAW conversion, automated watermarking. For teams processing sensitive imagery or anyone tired of per-image SaaS pricing, SnapOtter replaces a stack of subscriptions with one private container.

Adobe Acrobat and Smallpdf, answered by a self-hosted Java web application: Stirling PDF processes every file with its 60+ tools on your own server and deletes it after the task completes. Nothing is uploaded to a third party, which is the whole point for contracts, invoices, and medical records. The toolbox covers page operations (merge, split at page numbers or scanned dividers, rotate, reorder, crop, extract), conversion in both directions between PDF and Word, Excel, PowerPoint, images, HTML, and Markdown, OCR that turns scans into searchable PDFs via Tesseract/OCRmyPDF (including PDF/A archival conversion), and security tools for passwords, permissions, watermarks, signatures, and true UI-driven text redaction. A built-in viewer handles annotation, drawing, and text or image insertion, and V2 added stateful processing - upload once, chain multiple tools - plus undo/redo history. For automation, nearly every tool has a REST API endpoint, no-code pipelines combine operations into custom logic chains, and watched folders process files automatically. Enterprise deployments get SSO, user management, and audit logging; the interface ships in 40+ languages. With 84K+ GitHub stars it is the most popular PDF tool in self-hosting, replacing $20/month Acrobat subscriptions with flat infrastructure cost.

A spreadsheet whose formula language is real Python - full syntax plus the standard library, alongside familiar all-caps Excel functions: Grist is an open-source relational spreadsheet. Data lives in tables with typed columns and reference links, queried in formulas through lookupRecords and lookupOne, so one document can model what would otherwise take several joined spreadsheets. Trigger formulas compute values on conditions you define (timestamps, authorship, data cleanup, smart defaults), and an AI Formula Assistant generates formulas via OpenAI, Llama, or any OpenAI-compatible endpoint. Each document is a self-contained SQLite file, readable by any SQLite tool and trivially portable between hosts, with automatic snapshots and full-history exports. Layouts combine card, table, and chart widgets into dashboards, and granular role-based access rules restrict who sees which rows and columns - a design that made Grist a foundation of France's sovereign LaSuite workspace with 20,000+ government users. The Apache-2.0 grist-core edition ships SSO via OIDC and SAML, a REST API, webhooks, and forms; formula execution can be sandboxed with gVisor so untrusted documents cannot reach the network or each other.

A personal Strava on your own server: Endurain is a self-hosted fitness platform that keeps your complete workout history, GPS routes, and health data out of a vendor's cloud. It ingests the standard device formats (.gpx, .tcx, and preferred .fit with full sensor data) via manual or bulk upload, and syncs directly with Strava and Garmin Connect so migrating years of history is straightforward - Garmin sync covers activities, gear, and body composition. The dashboard shows activity feeds with weekly and monthly statistics, routes on maps, and distance, speed, and training-volume trends over time, with definable goals that update automatically. Gear tracking is notably deep: log wetsuits, bicycles, shoes, racquets, skis, and snowboards, assign default gear per activity type, and track individual components like bike chains against replacement mileage. Multi-user support with admin and user roles, follower features, per-activity privacy settings, and configurable sign-up (email verification, admin approval) make it usable for clubs and coaches as well as individuals. Auth is serious for a fitness app: MFA TOTP, OIDC/SAML SSO, and email-based password resets via Apprise. The stack is Vue.js over a Python FastAPI backend with PostgreSQL, plus weight, steps, and sleep logging, imperial/metric units, multi-language support, and third-party app integration.

What Nitter was to Twitter and Invidious is to YouTube, Lingva Translate is to Google Translate: a privacy front-end delivering the service's full capability while cutting Google out of the loop between you and your text. Built on Next.js with TypeScript and Chakra UI, it uses the purpose-built Lingva Scraper to fetch translations from Google Translate without your browser ever touching a Google-related service - no cookies, no tracking, no account, while retaining what makes Google Translate hard to give up: 100+ languages with the translation quality of Google's production models, unlike offline engines that trade privacy for accuracy. The clean interface covers automatic source-language detection, text-to-speech audio playback for pronunciations, definitions and examples, and light/dark themes. For developers, every instance doubles as a translation API: a RESTful endpoint at /api/v1/:source/:target/:query returns JSON translations, an audio endpoint serves TTS buffers, and a full GraphQL API at /api/graphql exposes translations, audio, and language lists for richer integrations - all unmetered on your own instance. Deployment is a single stateless container with one environment variable for the site domain; defaults for theme and language pair are configurable. GPL-licensed, and popular as the translation backend for privacy-respecting apps.

Sixty-thousand-plus GitHub stars make Uptime Kuma the most popular self-hosted monitoring tool - MIT-licensed, Node.js, and the standard replacement for UptimeRobot, Pingdom, and Freshping. It watches a dozen monitor types: HTTP(S) endpoints with keyword and JSON-query content validation, TCP ports, ICMP ping, DNS records, WebSockets, Docker containers via the socket, Steam game servers, MQTT brokers, gRPC services, and push-based heartbeats for cron jobs and internal workers. Checks run at intervals as tight as 20 seconds - versus UptimeRobot's 5-minute free tier - with unlimited monitors and unlimited data retention. When something fails, alerts fan out through 90+ notification channels: Slack, Discord, Telegram, email with LiquidJS templating, PagerDuty, OpsGenie, ntfy, Gotify, Matrix, and dozens more via native providers plus the Apprise library. Unlimited public or password-protected status pages - mappable to specific domains and organized into monitor groups - communicate health to customers, with maintenance windows that suppress alerts during planned work. The reactive dashboard graphs response times, tracks SSL certificate expiry with advance warnings, supports proxies and 2FA, and ships in dozens of languages. One Docker container with a SQLite volume covers an entire infrastructure.

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.

Forum software rebuilt on the modern web stack: NodeBB runs the classic bulletin-board format - categories, threads, local accounts - in real time, on Node.js over MongoDB, Redis, or PostgreSQL. WebSockets stream new posts into open topics as they're written and deliver instant notifications for follows, likes, and subscriptions; built-in chat supports side-by-side private conversations. The headline of recent versions is core ActivityPub federation: your forum can follow, share, and converse with other NodeBB instances, Mastodon, Lemmy, and anything else that speaks the protocol, turning an isolated community into a fediverse node. Everything beyond the common core is a plugin - more than 500 plugins and themes install in one click from the admin panel, covering SSO providers, search backends like Elasticsearch and Solr, galleries, calendars, and more. The theming engine extends base templates with SCSS/CSS on Bootstrap 5, plus a drag-and-drop widget system and custom HTML/CSS/JS injection. Operators get a real-time analytics dashboard, human-readable SEO-friendly URLs with semantic markup, multilingual UI, and full read and write REST APIs for integration. Mobile-first rendering means the same install works everywhere. For communities that outgrew phpBB but don't want Discourse's weight, NodeBB is the natural middle.