Run a Stack Overflow of your own: Apache Answer brings the question-and-answer format in-house, maintained under the Apache Software Foundation with an Apache-2.0 license. You use it to run a community forum, product help center, or internal knowledge base where content lives as questions and answers rather than wiki pages. It ships the mechanics that make that format work: voting, accepted answers, a reputation system with privilege levels, tagging, full-text search with filters, revision history on every edit, and admin/moderator/user roles. Content is written in Markdown with real-time preview and code syntax highlighting. A plugin system covers OAuth login (Google, GitHub), S3 storage, external search backends like Algolia, and Akismet anti-spam, and a REST API exposes platform data for integration. The backend is Go, the frontend React, and it runs against SQLite, MySQL, or PostgreSQL. Self-hosting replaces per-seat tools like Stack Overflow for Teams with a flat-cost instance where you own all the content.

With over 7,100 GitHub stars and 200 contributors since 2016, Mailu has become one of the most popular self-hosted email solutions, delivering a complete production-ready mail server stack as pre-configured Docker containers that eliminate weeks of manual setup. The platform bundles Postfix for SMTP and Submission with auto-configuration profiles for Thunderbird, Outlook, and mobile clients, Dovecot for IMAP and POP3 with full-text search across email attachments, Rspamd for intelligent spam filtering with auto-learn Bayesian classification, greylisting, SPF and DMARC validation, and ClamAV for antivirus scanning of attachments with configurable malicious file blocking. The web administration interface provides global admin controls, per-domain delegation, user quota management, domain aliases, custom routing rules, and announcement capabilities. Users access self-service features including aliases, auto-reply, auto-forward, fetched accounts from external mailboxes via fetchmail, and Sieve filter management through ManageSieve. Security features include enforced TLS on all connections, automatic Let's Encrypt certificate provisioning, outgoing DKIM signing, DANE and MTA-STS support for transport security, and Snuffleupagus PHP hardening for the web interface. The setup wizard at setup.mailu.io generates complete Docker Compose configurations tailored to specific deployment requirements. All components are free and open-source software with zero proprietary dependencies and no tracking. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.

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.

With nearly 10,000 GitHub stars and over a decade of development since 2013, Invoice Ninja is the most complete source-available invoicing platform for freelancers and small businesses — combining professional invoicing, online payments, expense tracking, and project management in a single self-hosted application. The Laravel API backend powers a React web portal and Flutter native applications for Windows, macOS, Linux, iOS, and Android, delivering a consistent experience across every device. Create professional invoices and quotes with real-time PDF preview, product libraries, custom templates, and automatic tax calculations. Clients receive branded emails and access their dedicated portal at your custom domain to view documents, approve quotes with e-signatures, and pay with one click via Stripe, PayPal, Square, GoCardless, Authorize.net, Braintree, or Mollie. Recurring invoices with auto-billing charge saved payment methods on schedule — weekly, monthly, or annually — with automatic reminders and late fee calculations. The built-in project management suite includes Kanban boards for task organization, billable time tracking with start/stop timers, and vendor expense management with receipt attachments. Bank account synchronization via Yodlee or GoCardless automatically imports transactions for reconciliation. E-invoicing with PEPPOL network integration supports electronic invoicing standards for European and government compliance. Reports cover invoices, expenses, profit and loss, tax summaries, and aged receivables. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. Elastic License v2.

Webstudio delivers a professional-grade visual website builder that outputs semantic HTML and clean CSS without inline style pollution or JavaScript-heavy render paths. The live canvas editor provides direct manipulation of all CSS properties — flexbox, grid, spacing, typography, transforms, and filters — with real-time preview across responsive breakpoints. The component system supports reusable instances with variants and overrides, while design tokens maintain consistent colors, fonts, and spacing across the entire site. Data bindings connect to external content sources through native integrations with Strapi and Supabase, plus a generic CMS interface for any REST API backend. The Scroll Timeline API powers animations at 120 FPS off the main thread, with presets for rotate, scale, translate, opacity, color, and filter effects. Projects build as dynamic Remix applications with server-side rendering or export as static HTML, CSS, and JavaScript files. The Webstudio CLI generates Docker-ready builds that run a Node.js server on port 3000, with Nginx reverse proxy configuration for SSL termination via Let's Encrypt. The builder requires minimum 1 GB RAM and 1 CPU core for Docker builds. MCP integration enables AI agents to create and modify websites programmatically. On RepoCloud, deploy Webstudio projects on a dedicated VPS with root SSH access, persistent storage, and complete control over your hosting, custom domains, and deployment pipeline, all under the AGPL-3.0 license.

With over 47,000 GitHub stars, Cal.diy is the fully open-source community fork of Cal.com that strips away every proprietary license gate and enterprise paywall to deliver a pure MIT-licensed scheduling platform you completely own. The booking engine supports individual event types including recurring events, seated events with capacity limits, and paid bookings through Stripe and PayPal, all backed by customizable availability schedules with date overrides, buffer times, minimum notice periods, and travel schedule support. Calendar synchronization is bidirectional across nine providers — Google Calendar, Outlook and Office 365, Apple Calendar, CalDAV, Lark, Feishu, Zoho, Exchange, and ICS feeds — so every booking automatically appears on your existing calendar while blocking conflicting slots. Video conferencing links generate automatically for Zoom, Google Meet, Microsoft Teams, Webex, Jitsi, Daily.co, Whereby, and Huddle01, eliminating manual link management. The automation layer connects through webhooks, Zapier, n8n, Make, and Pipedream to CRM platforms like HubSpot, Salesforce, and Close, messaging services including Discord, Telegram, and WhatsApp, and analytics tools such as Google Analytics 4, PostHog, and Fathom. The entire application is built on the T3 stack — Next.js for server-rendered pages, tRPC for end-to-end type-safe APIs, Prisma for PostgreSQL database access, and Tailwind CSS for the responsive interface. Unlike Cal.com's open-core model, Cal.diy requires no license key and includes no gated features. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.

Processing billions of operations per second across companies like Twitter, GitHub, Snapchat, and Stack Overflow, Redis is the world's fastest and most widely deployed in-memory data store. Redis 8 unifies previously separate modules into a single distribution: RediSearch for full-text indexing with BM25 scoring and vector similarity search via HNSW and FLAT algorithms, RedisJSON for native JSON document storage with JSONPath queries, RedisTimeSeries for timestamped data with configurable downsampling compaction rules, and RedisBloom for probabilistic data structures including Bloom filters, cuckoo filters, count-min sketches, top-k, and t-digest. The core engine provides strings, lists, sets, sorted sets, hashes, streams, HyperLogLog, bitmaps, bitfields, geospatial indexes, and the new array data structure introduced in Redis 8.8. Pub/Sub delivers lightweight real-time messaging between publishers and subscribers, while Streams provide an append-only log with consumer groups for event sourcing and complex consumption patterns. Redis Cluster distributes data across nodes with automatic sharding using 16,384 hash slots, and Sentinel provides high availability with automatic failover monitoring. Lua scripting and Redis Functions enable server-side computation, and ACL-based security provides granular per-command, per-key access control. Official clients exist for Python, Node.js, Java, Go, .NET, Rust, and PHP. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. AGPLv3 licensed.

Shelf answers the three questions every equipment manager dreads — who has it, where is it, and when is it coming back — using QR-code-first tracking where every asset gets a unique scannable label, every handover is logged with timestamps and e-signed custody agreements, and every scan captures GPS coordinates displayed on a map. Built on React Router 7 with React 19, TypeScript 5, Prisma 6 ORM, and Tailwind CSS 3 with Radix UI components, the platform generates QR codes and barcodes (Code128, Code39, Datamatrix) printable on DYMO, Brother, and Zebra label printers. The custody system records every handover with user details and generates PDF custody agreements with e-signatures for high-value items, while a complete audit trail tracks responsibility from check-out to return. The visual booking calendar prevents double-bookings automatically, supports partial check-outs and returns with segmented lifecycle bars, and handles quantity-tracked consumables alongside individually serialized equipment. Asset Models enable bulk creation of identical items with shared defaults while maintaining individual QR codes and custody histories. Location tracking displays last-scanned GPS coordinates on MapTiler maps. Supabase Auth provides email and SSO authentication, pg-boss handles background job queuing, and Nodemailer delivers SMTP email. The Shelf Companion app on iOS and Android enables field scanning and bookings. Export Asset Inventory, Asset Distribution, and Custody Snapshot reports for compliance. Deploy via Docker with PostgreSQL and Supabase. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. AGPL v3.0 licensed.

With nearly 9,000 GitHub stars and adoption by over 60,000 companies across 100 countries, Papermark is the open-source DocSend alternative that turns document sharing into a data-rich conversation between you and your viewers. Every shared document generates page-by-page analytics showing exactly which pages capture attention, how long viewers spend on each section, where they drop off, and whether they return for a second look, with real-time notifications the moment a document is opened. Virtual data rooms support unlimited folders with drag-and-drop organization, bulk uploads, granular per-viewer permissions, dynamic watermarking that stamps each page with the viewer's identity, and NDA gating that requires agreement before access. Custom branding applies your logo, colors, and custom domain to every shared link and download page, while email verification and password protection add authentication layers. The AI Data Room Copilot lets viewers chat with uploaded documents, ask questions, and receive contextual summaries directly within the data room interface. The developer platform exposes 43 REST API operations covering data rooms, documents, folders, links, visitors, and analytics, with an MCP server for AI agent integration and a CLI for automation. Built on Next.js with TypeScript, Prisma ORM, PostgreSQL, NextAuth.js authentication, and shadcn/ui components. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. AGPLv3 licensed.

Backed by nearly 80,000 GitHub stars and recognized as one of the most popular developer tools in the open-source ecosystem, Hoppscotch delivers a complete API development platform that runs instantly in any browser with zero installation. The platform supports six protocols out of the box including REST with full HTTP method coverage, GraphQL with schema introspection and multi-column documentation, WebSocket for full-duplex communication, Socket.IO, MQTT for IoT messaging, and Server-Sent Events for real-time streaming. Request collections organize your API calls into logical groups with support for sub-folders, environment variables with scope inheritance, pre-request scripts and post-request test scripts written in JavaScript, and automatic code snippet generation in over twenty languages and frameworks. Teams can collaborate in real-time with shared workspaces, role-based access controls, and cloud synchronization across devices. Migration from Postman, Insomnia, or OpenAPI specifications happens with a single click import. The self-hosted edition deploys via Docker Compose with PostgreSQL for data persistence, supporting SSO authentication through SAML and OAuth providers, SMTP configuration with OAuth2, and admin dashboard for user management. The platform also ships as a native desktop application for macOS, Windows, and Linux with offline support, plus a CLI tool for running collections in CI/CD pipelines. A built-in proxy mode bypasses CORS restrictions during development, and an interceptor enables request debugging and response modification. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.

With over 14,000 GitHub stars and enterprise adoption by security-conscious organizations, Coder transforms how development teams provision, manage, and secure their coding environments. Every workspace is defined as a Terraform template, meaning infrastructure engineers can standardize development environments across EC2 instances, Kubernetes pods, Docker containers, or any combination, while developers get self-service provisioning that launches in seconds rather than days of manual setup. The WireGuard-based networking layer establishes encrypted tunnels between developer machines and remote workspaces, providing low-latency access without exposing ports or configuring VPN concentrators. Automatic idle detection shuts down unused workspaces after configurable periods, directly reducing cloud compute costs for organizations running hundreds of developer environments. The Coder Agents feature introduces native AI coding capabilities where the agent loop executes entirely within the control plane on self-hosted infrastructure, keeping LLM API credentials out of individual workspaces and eliminating credential exfiltration risks. Centralized model governance allows platform teams to approve specific AI providers and models, set per-user spend limits, and maintain complete audit logs of all prompts, tool calls, and agent activity. IDE integration supports VS Code through a dedicated extension, JetBrains IDEs via Gateway and Toolbox plugins, and browser-based code-server for web access. The template registry provides pre-built configurations for common development stacks. DevContainer support builds environments from standard devcontainer.json specifications. Deploy on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. AGPL-3.0 licensed.

A private ChatGPT built with Next.js: Lobe Chat is the open-source AI chat interface teams self-host instead. Its main advantage is provider breadth: one interface connects to 40+ model providers, including OpenAI, Anthropic Claude, Google Gemini, Mistral, Groq, AWS Bedrock, Azure, and local models served through Ollama, so you can switch models per conversation and compare outputs. It handles multi-modal work: image recognition, image generation, text-to-speech, and speech-to-text. A plugin system based on function calling and the Model Context Protocol (MCP) adds external tools like web search and code execution. Run it in standalone mode as a single container with settings in browser storage, or in database mode with PostgreSQL and S3-compatible storage for persistent history, multi-user auth, and RAG knowledge bases built from uploaded documents with pgvector retrieval. Because tools arrive through function calling and MCP rather than a proprietary plugin format, custom internal tools can be exposed to the assistant with a standard server over STDIO or HTTP. Hundreds of pre-configured assistant roles import from the community marketplace. For teams the cost model matters: provider API keys billed per token typically undercut a ChatGPT Plus seat per person, and self-hosting keeps API keys, uploaded files, embeddings, and conversation history entirely on your own server.

Quote to cash in one web application - create quotes, convert them to invoices, record payments, track customers: iDURAR is an open-source ERP and CRM platform for small and medium-sized businesses. Built on the MERN stack (MongoDB, Express, React, Node.js) with Ant Design components and Redux state management, it presents a clean SaaS-style interface that needs little onboarding. Core modules cover invoice management with PDF generation and email delivery, payment recording against invoices, quote and proforma handling, customer records, and accounting views over the resulting data. Multi-currency support and localization make it usable for internationally operating teams. Because the whole stack is JavaScript with an API-first backend, extending it - custom fields, new modules, integrations - is approachable for any Node/React developer rather than requiring a specialist ERP skill set. Deployment is straightforward via Docker with a MongoDB instance. Licensed under AGPL-3.0 with free commercial use; a hosted enterprise version exists but the self-hosted edition is fully functional.

With over 110,000 GitHub stars and one of the fastest-growing open-source communities in the self-hosted space, Immich delivers a Google Photos-grade experience entirely on your own hardware. The platform handles automatic background backup from Android and iOS devices, deduplication, and support for RAW formats, LivePhotos, and MotionPhotos. Its machine learning pipeline runs facial recognition and clustering locally on your server, enabling you to group photos by person without sending a single image to the cloud. CLIP-based semantic search lets you find images by describing their content in natural language, while metadata-driven search covers EXIF data, dates, and locations. The web interface built with SvelteKit provides a responsive timeline view, albums, shared albums with configurable permissions, public sharing links with optional passwords and expiry dates, partner sharing for family libraries, and a global map plotting photos by GPS coordinates. Administrative features include multi-user support with per-user storage quotas, OAuth integration, API key management, and a user-defined storage structure for organizing files on disk. The architecture uses PostgreSQL for metadata, Redis with BullMQ for background job queues handling thumbnail generation, video transcoding, and smart search indexing, and exposes over 400 REST API endpoints documented via OpenAPI with auto-generated SDKs for web, mobile, and CLI clients. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. AGPL-3.0 licensed.

The most-starred open-source project management platform on GitHub with over 55,000 stars, Plane delivers what Jira, Linear, Monday, and ClickUp charge thousands per year for — issue tracking, sprint planning, documentation, and AI-powered workflows in one unified workspace that you own and control entirely. Work items feature a rich text editor with file uploads, sub-properties, custom states, priorities, labels, assignees, and cross-referencing, organized across five customizable layout views (list, board, table, spreadsheet, Gantt) with Command-K navigation for instant access to anything. Time-boxed Cycles provide sprint planning with automatic burn-down charts, velocity tracking, and scope change detection, while Modules break complex projects into manageable deliverables with progress aggregation. Built-in Pages combine AI-powered documentation with rich formatting, image embedding, and one-click conversion of notes into actionable work items. The AI layer reads across every project, cycle, document, and thread in the workspace — agents take real assignments, triage incoming requests, assign owners, track blockers, and ship status updates automatically. Native integrations connect GitHub, GitLab, Slack, Sentry, Figma, and 50+ tools with bidirectional issue sync and PR tracking, while import pipelines migrate entire workspaces from Jira, Linear, Asana, ClickUp, or Monday in minutes. The REST API with OAuth 2.0, HMAC-signed webhooks, typed SDKs in Node.js and Python, and a native MCP server enable custom automations. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. AGPL-3.0 licensed.

Grammar, punctuation, and style errors a dictionary lookup can't see: LanguageTool is open-source proofreading powered by a Java rule engine covering English, German, Spanish, French, Portuguese, Dutch, and 25+ other languages. Self-hosting the HTTP server is how you get Grammarly-class checking without sending every sentence you write to a third party - a real concern when the text being proofread is confidential email, legal drafts, or unreleased documentation. Your instance exposes the standard /v2/check API, so the official ecosystem plugs straight in: browser extensions for Chrome and Firefox accept a custom server URL, and integrations exist for VS Code, LibreOffice, Obsidian, Vim, Emacs, and many editors. Notably, self-hosting restores free browser-extension checking that the hosted service moved behind a premium subscription - your server, no character limits, no paywall. Detection quality is tunable: optional n-gram datasets (multi-gigabyte language models for en, de, es, fr, nl) teach the engine word-order and confusion-pair errors like there/their and brakes/breaks, and a fastText model improves automatic language identification. Everything runs offline once models are downloaded. The core is LGPL, the API is documented with Swagger, and rules are community- maintained and constantly expanding.

Originally built at Netflix to orchestrate microservices powering 230 million subscribers and now trusted in production at Tesla, LinkedIn, and J.P. Morgan, Conductor is the most battle-tested open-source workflow engine available — with 32,000 GitHub stars and horizontal scalability to billions of executions. The architecture cleanly separates orchestration from business logic: workflows are defined in declarative JSON while workers execute tasks in any of seven supported languages (Java, Python, Go, JavaScript, C#, Ruby, Rust) with zero framework constraints. Durable execution persists every state transition, enabling automatic retries, configurable timeouts, crash recovery, and instant replay from any failure point without re-executing completed tasks. Native AI agent orchestration supports 14+ LLM providers (Anthropic, OpenAI, Google Gemini, AWS Bedrock, Mistral, Cohere, HuggingFace, Ollama), MCP tool calling, function calling, human-in-the-loop approval gates, and vector database integration (Pinecone, pgvector, MongoDB Atlas) for RAG pipelines. Deploy with your choice of five persistence backends (PostgreSQL, Redis, MySQL, Cassandra, SQLite), six message brokers, and Elasticsearch or OpenSearch for workflow indexing — all configurable via Docker Compose files included in the repository. The built-in web UI provides workflow visualization, execution monitoring, task queue inspection, and manual intervention controls. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. Apache-2.0 licensed.

What Gmail did for email, Octobox does for GitHub notifications: an ephemeral, unmanageable stream becomes an inbox you can actually triage. GitHub marks notifications read the moment you glance at them and lets old ones vanish days later; heavy maintainers end up building elaborate Gmail filter systems just to cope. Octobox - a Ruby on Rails app over PostgreSQL - syncs your notifications into a persistent inbox with an explicit archived state: mark a thread done, and if the issue or PR sees new activity, it pops back automatically, so nothing silently falls through. Triage is keyboard-driven with Gmail-style shortcuts (j/k to navigate, e to archive, m to mute, s to star), and multi-select clears noisy repositories in bulk. Filtering is where it earns its keep: slice by repository, organization, type, action, state, reason, CI status, labels, author, assignee, or bot origin, combine prefix search filters, and pin favorite searches to the sidebar. The optional GitHub App enriches entries with live PR/CI status and labels so you can decide without clicking through. Auto-archive rules clear merged PRs and closed issues; muting and snoozing silence the rest. A REST API supports integrations. Self-hosting keeps your notification metadata - a map of everything you work on - on your own server.