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.

Scheduling infrastructure, not just a booking page - Cal.com is the leading open-source scheduling platform. Share a link, attendees pick a slot, and real-time sync against Google Calendar, Outlook, and CalDAV prevents double-booking. Beyond the basics it covers team workflows: round-robin distribution, collective availability across multiple hosts, recurring meetings, and routing forms that ask bookers questions and send them to the right team member - the feature sales and support teams usually pay enterprise prices for. Paid bookings run through Stripe, video calls through the built-in Cal Video (Daily.co) or Zoom and Google Meet, and an app store connects 100+ tools including HubSpot, Zapier, and n8n. The API-first architecture with webhooks and embeds makes it practical to build scheduling into your own product, white-labeled with your domain and branding. Built on Next.js and Prisma over PostgreSQL, translated into 65+ languages, with the self-hostable community codebase maintained under an open-source license.

Zigbee2MQTT bridges a Zigbee smart home network to MQTT so bulbs, switches, sensors, and locks from hundreds of vendors work with your own automation server instead of each manufacturer's cloud bridge. It supports 5,798 devices from 608 vendors, so a Philips Hue bulb, an IKEA TRÅDFRI switch, an Aqara sensor, and a Tuya plug can all join one coordinator and speak one protocol. The built-in frontend on port 8080 shows every paired device with its link quality, battery level, and live state, and lets you rename, reconfigure, bind, or remove devices without editing YAML. A network map view charts which routers carry traffic for which end devices, making weak spots and dead zones visible before automations start failing. Groups collect devices that should act together, scenes capture lighting states for a room, and bindings let a switch talk directly to a bulb even when the server is briefly offline. Firmware stays current through over the air updates you can trigger or schedule per device from MQTT topics or the frontend, including downgrades when a new release misbehaves. Home Assistant picks everything up automatically through MQTT discovery, while openHAB, Domoticz, and Node-RED flows subscribe to the same plain JSON topics. The coordinator plugs into the host by USB or joins over the local network, while the bridge, frontend, and broker traffic run headlessly beside Mosquitto or EMQX. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. GPL-3.0 licensed.

A budget model, the launch document that explains it, and the slides that present it can live side by side in one self-hosted office workspace that people and AI agents edit together. Personal and Team Spaces organize Sheets, Docs, Slides, relational Bases, and Boards, with Recent, Trash, file import, and export views keeping everyday housekeeping close at hand. Sharing follows role and node aware access control, including anonymous viewing, so a single table or document can be opened to a reader without exposing the whole space. Data and references stay connected across artifacts as the workspace changes, which keeps a figure corrected in a sheet consistent with the document that quotes it. The Workspace Agent drafts and revises content in isolated Worktrees, verifies its own changes, and hands the result to a person for review before anything reaches the trunk. Several review rounds can happen while humans keep editing in the Browser, and nothing merges until someone approves it. The Workspace CLI connects existing agents to your deployment, so automation can create content, inspect data, render screenshots and PDFs, and run layout checks before review. Sign-in accepts passwords, GitHub, Discord, or application OAuth, and files move in and out as XLSX, DOCX, PPTX, and CSV without a separate conversion project. 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.

Retool's job, self-hosted: ToolJet is an open-source low-code platform for building internal tools, dashboards, and admin panels. Apps are assembled in a drag-and-drop visual builder with 60+ responsive components, including tables, charts, forms, and lists, and connected to 80+ data sources: PostgreSQL, MySQL, MongoDB, REST and GraphQL APIs, cloud storage, and common SaaS tools. When visual configuration is not enough, you can run JavaScript or Python inline for queries and transformations. A built-in no-code database (ToolJet Database) covers apps that need their own tables without provisioning an external database, Workflows add node-based automation for background jobs with dedicated worker containers and a Redis-backed queue, and multi-page apps with multiplayer editing, inline comments, and mentions support team development. Security is designed for internal data: credentials are AES-256-GCM encrypted, data flows proxy-only through your server so database contents never reach a third-party cloud, and granular per-app access control plus SSO gate each tool. Where Retool-style platforms bill per builder and sometimes per end user, the self-hosted Community Edition serves unlimited builders and users at hosting cost, and full source availability means the platform itself can be forked, audited, and extended. The stack is Node.js and React on PostgreSQL, deployed via Docker.

With nearly 14,000 GitHub stars and over 200 releases, Semaphore UI has established itself as the lightweight yet powerful alternative to enterprise automation platforms like Ansible AWX and Jenkins. Unlike AWX's heavyweight Kubernetes-dependent architecture, Semaphore ships as a single Go binary with zero external runtime dependencies — install it, run setup, and you have a production-ready automation server in minutes. The platform natively orchestrates Ansible playbooks, Terraform and OpenTofu infrastructure code, Terragrunt configurations, PowerShell scripts, Bash commands, and Python automation, all from a clean Vue.js web interface that displays task history, execution logs, and scheduling status at a glance. Semaphore supports concurrent task execution across multiple servers using distributed project runners, enabling horizontal scaling of automation workloads without complex clustering. The built-in inventory management system handles both static and dynamic inventory sources, while four-level RBAC (Owner, Manager, Task Runner, Guest) provides granular access control for team environments. Notifications flow to Slack, Microsoft Teams, Telegram, email, Rocket.Chat, and Gotify, keeping operators informed of failed tasks and deployment status. Integration with HashiCorp Vault secures sensitive credentials, and the comprehensive REST API with built-in Swagger documentation enables programmatic automation. Deploy via Docker Compose, Helm chart for Kubernetes, or native packages for Debian, Ubuntu, and RHEL-based distributions. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.

Security scanners each report in their own format, and DefectDojo is the self-hosted platform that imports those reports and keeps a single, triaged list of findings. Reports in mixed formats? More than 350 built-in parsers read output from Burp Suite, ZAP, Trivy, Tenable Nessus, SonarQube, Snyk, and Checkmarx, and Generic Findings Import covers tools without a parser through CSV or JSON files. The same scan every night? Reimport adds new findings, can close the ones that vanished, and reopens the ones that return, while deduplication ties repeat detections inside an asset to their original. Decisions already made? False positive, out of scope, and risk accepted statuses survive reimport, so nobody triages the same noise twice. A deadline on every fix? Severity-based SLA countdowns flag breaches and can notify the users assigned to each asset, and full risk acceptances carry notes, files, and an expiry date that returns findings to active by default. Many teams, many applications? Organizations, assets, engagements, and tests mirror how security work is organized, with permissions that cascade downward. Pipelines that should report themselves? The REST API and CI/CD engagements import results automatically, and findings push to Jira as tickets. Someone outside security wants a summary? Dashboards track metrics, and a widget-based report builder produces HTML reports that print to PDF. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. BSD-3-Clause licensed.

With over 35,000 GitHub stars and 460 contributors, Medusa is the headless commerce framework that gives development teams full ownership of their e-commerce backend without license fees, per-transaction charges, or revenue sharing. The modular architecture ships over 18 domain modules covering products, collections, categories, inventory, pricing, carts, orders, payments, fulfillment, promotions, customers, users, API keys, and stock locations, each independently usable and replaceable. REST and GraphQL APIs expose every commerce operation to any frontend framework — official starters exist for Next.js with community options for Nuxt, Remix, and Gatsby. The React-based admin dashboard provides out-of-the-box order management, product maintenance, promotions configuration, B2B accounts, and multi-warehouse inventory, extensible via the Admin SDK for custom views and workflows. The workflow engine orchestrates long-running commerce processes like checkout, fulfillment, and returns with compensating transactions for reliability. Over 200 official and community plugins integrate Stripe, PayPal, Klarna, Algolia, Meilisearch, SendGrid, Mailchimp, Contentful, Sanity, and Klaviyo. Native multi-region and multi-currency support handles tax-inclusive pricing, region-specific payment and fulfillment providers, and localized storefronts from a single backend. Enterprises including Viessmann, Makro PRO, and INSPIRED Pet Nutrition run Medusa in production. Self-hosting deploys via Docker or directly on Node.js with PostgreSQL and Redis. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.

The movie half of the *arr stack: Radarr is a .NET collection manager that automates acquiring films for Usenet and BitTorrent users the way Sonarr does for TV. Add a movie once and Radarr handles the rest: it monitors indexers and RSS feeds, grabs a matching release the moment one appears, sends it to SABnzbd, NZBGet, qBittorrent, Deluge, Transmission, rTorrent, or another connected download client, then imports, sorts, and renames the file into your library structure. Quality profiles are the control surface - define allowed resolutions and a cutoff, and Radarr keeps upgrading files automatically, replacing a DVD rip when a Blu-ray release lands. Custom formats go further, scoring releases by codec, HDR metadata, release group, streaming source, or arbitrary regex so the copy you want always wins the pick. Failed downloads retry with another release automatically; a manual search shows every candidate and explains why one was skipped. Release parsing recognizes director's cuts, special editions, AKA titles, and hardcoded subs. Plex and Kodi integration handles notifications, library refreshes, and metadata like posters, trailers, and subtitles, and a calendar view tracks upcoming releases. It pairs naturally with Jellyseerr for request management and shares its API conventions with the whole *arr ecosystem.

With over 13,000 GitHub stars and active monthly releases, Mailcow delivers a production-ready mail server infrastructure through Docker Compose orchestration of twelve integrated containers. The stack pairs Postfix as the MTA handling SMTP traffic with Dovecot for IMAP and POP3 retrieval featuring the Flatcurve full-text search engine, while Rspamd provides machine-learning-powered spam filtering with Bayesian classification, DKIM signing, and ARC support. ClamAV scans attachments for malware including Office document macro analysis via Olefy, and SOGo serves as a responsive webmail client with CalDAV, CardDAV, and Microsoft ActiveSync synchronization. The admin panel manages multiple domains, per-user spam score thresholds, quarantine review, black and whitelists, temporary spam aliases, mailbox quotas, and TLS enforcement policies for both inbound and outbound messages. Security features include two-factor authentication via TOTP, WebAuthn, and Yubikey OTP, a Fail2ban-like Netfilter integration for brute-force protection, and automatic SPF, DKIM, and DMARC configuration. The ACME container handles Let's Encrypt certificate generation with DNS-01 challenge support, while Postfix TLS-Pol provides MTA-STS and DANE/TLSA resolution for encrypted transport. Built-in imapsync enables periodic migration from remote mailboxes, and the REST API allows programmatic management of all server resources. MariaDB stores user data, Redis caches configuration and sessions, and Unbound provides local DNSSEC-validating DNS resolution. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. GPL-3.0 licensed.

The open-source PaaS with 55,000+ GitHub stars and the largest one-click service catalog in its class — Coolify gives you the Vercel push-to-deploy workflow on a dedicated server you control. Connect a GitHub, GitLab, Bitbucket, or Gitea repository and every push builds and deploys automatically via Nixpacks, a Dockerfile, or Docker Compose, with Traefik or Caddy reverse proxying, automatic Let's Encrypt certificates, and per-branch preview deployments with their own URLs. Databases — PostgreSQL, MySQL, MariaDB, MongoDB, Redis — provision in a few clicks, and a catalog of 280+ one-click service templates covers WordPress, n8n, Grafana, MinIO, Plausible, Ollama, and more. One dashboard manages the entire server, with Docker Swarm available for clustering multiple nodes. Backups go to any S3-compatible storage with one-click restore, and a full API supports CI/CD integration. All configuration lives on your own server, so resources keep running even if you stop using Coolify — no vendor lock-in by design. Running on a dedicated VPS with guaranteed CPU, RAM, and SSD, full root access via SSH and browser console. Apache 2.0 licensed.

Most wikis die of flat page-and-tag sprawl; BookStack's defining decision is enforced structure - an MIT-licensed PHP/Laravel platform (over MySQL) where content lives in a hierarchy of shelves, books, chapters, and pages, the way a physical library works. A shelf maps to a department, a book to "Engineering Runbooks," a chapter to "Database Procedures," a page to the actual document. That opinionation removes the "where does this go?" friction and keeps knowledge bases tidy as they grow. Editing works both ways: a clean WYSIWYG editor for most users, a Markdown editor with live preview for those who prefer it - switchable per page. Full-text search spans all books or scopes to one, with direct links to individual paragraphs, and include tags let you embed one page's content inside another so shared blocks update everywhere at once. Every edit creates a diffable, revertible revision. Page templates standardize recurring formats, tags add cross-cutting categorization, and built-in diagrams.net integration draws architecture diagrams in place. Authentication covers email/password plus OIDC, SAML2, LDAP, and social login; a full role and permission system locks content down per shelf, book, or page. Pages and books export to PDF, HTML, plain text, and Markdown, a REST API automates content, and the whole thing runs happily on the cheapest VPS you can find.

With over 6,500 GitHub stars, HolaOS bills itself as an "open agent computer" that reimagines the traditional operating system as a shared workspace where humans and AI agents collaborate across files, browsers, and 100+ integrated tools simultaneously. Unlike chat-only interfaces, HolaOS places live application UIs—Notion-style editors, browsers, custom workspace apps—side by side with the agent conversation, so operators always see what agents are doing and can intervene at any moment. The persistent memory system stores workspace knowledge locally as Markdown files and embedded vectors via SQLite vec, enabling RAG-powered recall that survives session boundaries without the typical context window bloat. Safe Session Compaction reserves roughly 70% of the model context window for fresh reasoning while folding older history into structured checkpoints that retain goals, constraints, progress, and decisions. Agents connect to Linear, GitHub, Slack, Jira, HubSpot, Gmail, and dozens more through one-click OAuth, automatically fetching relevant signals and converting scattered app data into working memory. BYOK support for Claude, GPT, and Gemini models lets operators use their own API keys at zero markup, while built-in Kimi K3 and GLM-5.2 models provide ready-to-use alternatives. Skills package reusable workflows that any agent can invoke on demand, and scheduled triggers enable autonomous digests, monitors, and reports. The runtime supports independent server deployment alongside the desktop client. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. Modified Apache 2.0 licensed.

With 23,600 GitHub stars, 13 million monthly PyPI downloads, and 425+ contributors automating over 200 million data tasks monthly for Fortune 50 companies like Progressive Insurance and disruptors like Cash App, Prefect is the most widely deployed open-source workflow orchestration framework for Python — turning any script into a resilient production pipeline with a single @flow decorator while eliminating rigid DAG structures entirely. The durable execution engine persists task results and automatically resumes from failures without replaying expensive upstream work, guaranteeing exactly-once execution for any Python function. Event-driven automation triggers workflows from webhooks, cloud events, or state changes through a real-time event bus that detects what happens or fails to happen across your entire data platform. Work pools decouple workflow code from infrastructure, enabling seamless switching between Docker, Kubernetes, AWS ECS, Azure Container Instances, GCP Cloud Run, and serverless environments without modifying pipeline logic. Native Ray and Dask task runners extend execution across clusters for compute-intensive workloads. The self-hosted server provides a monitoring dashboard with flow run timelines, task state visualization, scheduling, and automation configuration. The third-generation engine reduces overhead by over 90 percent compared to Prefect 2, supporting batch, event-driven, interactive, and background task workflows. Deploy via Docker Compose with PostgreSQL, Redis, server, background services, and worker containers, or use official Helm charts for production Kubernetes. 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.

CKAN lets governments, research institutions, and companies publish data as a searchable catalog, where every dataset carries its description, license, tags, and downloadable files. Organizations own their datasets, and members, editors, and admins get different rights, so a dataset can stay private until someone with publishing rights releases it. Visitors narrow results with faceted filters on tags, formats, and organizations, or write fielded queries with wildcards and fuzzy matching. Resource pages preview spreadsheets in a grid and, when the data fits, as maps and charts, and they also display images, PDFs, and HTML. The DataStore keeps tabular resources as queryable tables, serving filtered rows with range conditions and nested AND/OR logic. Everything the web interface does is also available through the Action API. Groups gather related datasets, and custom metadata fields extend each record. Per-dataset activity streams document how data changes, and follow buttons feed a personal news feed. Files can be stored on local disk or, with extensions, in S3, Google Cloud Storage, or Azure Blob Storage. Extensions add geospatial search, harvesting for federated portals, multilingual metadata, and more chart types, and themes restyle the portal to match your brand. 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.

Backed by over 36,000 GitHub stars and 120 contributors with 123 releases since 2022, 1Panel has rapidly become the go-to open-source alternative to cPanel and Plesk for modern Linux server management. The platform delivers a clean Vue.js dashboard powered by a Go backend using the Gin framework, providing visual management of Docker containers, images, networks, and volumes without touching the command line. Its curated app marketplace offers one-click installation of 165+ trusted open-source applications including Nextcloud, Bitwarden, Umami analytics, WordPress, and NocoBase, each running in isolated containers for maximum security. Native AI capabilities set 1Panel apart from every competing panel: deploy Ollama LLMs directly from the dashboard, spin up OpenClaw personal agents, monitor GPU utilization, and manage AI models through a unified interface. Website management includes automatic domain binding, Let's Encrypt SSL certificate provisioning, and Nginx configuration with zero manual setup. Security runs deep with built-in firewall rules, fail2ban integration, container isolation, WAF protection, and comprehensive audit logging enabled from day one. Automated backups support AWS S3, Cloudflare R2, and local storage with one-click restore from any snapshot. The panel supports Debian, Ubuntu, CentOS, and Rocky Linux across x86_64, aarch64, armv7l, ppc64le, and s390x architectures. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. GPL-3.0 licensed.

Deployed at thousands of enterprises across financial services, healthcare, government, and telecommunications, Apache NiFi is the industry-standard platform for building automated data pipelines through a visual drag-and-drop browser interface that requires zero coding for common integration patterns. The flow-based programming model connects over 300 built-in processors covering relational databases via ExecuteSQL and PutDatabaseRecord, Apache Kafka with PublishKafka and ConsumeKafka, HTTP endpoints through InvokeHTTP and ListenHTTP, cloud storage for AWS S3, Azure Blob, and Google Cloud Storage, SFTP/FTP file transfers, and JSON, XML, CSV, and Avro transformations. Data provenance tracking logs every routing decision, transformation, and delivery for every FlowFile, creating a searchable lineage graph from source to destination with full content replay capability for auditing and debugging. Guaranteed delivery uses configurable backpressure thresholds, prioritized queuing with latency or throughput optimization, and automatic retry with exponential backoff, ensuring no data loss even during downstream outages. The zero-leader clustering architecture distributes processing across nodes with automatic load balancing, while site-to-site protocol enables secure data transfer between NiFi instances across network boundaries. Security includes OpenID Connect and SAML 2.0 single sign-on, role-based access control with fine-grained policies per component, and TLS encryption for all communication. Custom processors can be written in Java and packaged as NAR bundles, or implemented directly in Python through the native scripting framework. 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.

With MediaWiki, the wiki software behind Wikipedia, a team writes one shared knowledge base in plain wikitext or a visual editor while every revision stays saved for comparison and rollback. Page history names the author and edit summary of each change, and a side-by-side diff shows exactly what moved before anyone reverts. Talk pages hold threaded discussions with inline replies, notifications announce mentions and thanks, and watchlists flag the pages you follow. Namespaces, categories, redirects, and reusable templates give a large wiki its structure, and Lua modules written for Scribunto power infoboxes. Uploaded images get automatic thumbnails and a full-screen lightbox. Bundled extensions add PDF handling and math rendering for documentation that needs more than text. Group-based permissions decide who may read, edit, protect, or delete. A wiki can stay open to everyone or sit behind a login. AbuseFilter, CAPTCHAs, blocklists, and two-factor sign-in help fend off spam and account takeovers. Vector 2022 brings a sticky table of contents and an optional dark mode. The interface is localized in over 350 languages. Bots and scripts log in, read, search, and edit with the Action API. Use it for company handbooks, engineering runbooks, course notes, fandom encyclopedias, and public reference sites. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. GPL-2.0-or-later licensed.