From the call for abstracts to the badge handed over at the registration desk, Indico handles every step of running a conference, plus the weekly meetings and one-off lectures that fill the calendar around it. Events live in a nested tree of categories, and access rules can be set per category, event, session, or single contribution, with custom roles inside each event. Speakers submit abstracts, track reviewers score them against questions the organizers define, judges accept or reject them, and accepted talks become contributions that sit in a drag-and-drop timetable of color-coded sessions. Registration forms are assembled field by field, carry fees, and take payment through PayPal, Stripe, or SIX Payment plugins; attendees get QR-coded tickets, and a badge editor prints name tags for the whole room. A paper reviewing workflow collects full papers. Meeting pages keep minutes and slide decks attached to the talk they belong to. The room booking module adds approvals, recurring reservations, and audiovisual equipment, and the Zoom plugin creates online sessions straight from an event page. Calendar views span a month, week, or day, filter by category, and export to iCal for subscriptions. Scripts pull event data from the HTTP export API as JSON or XML with personal API tokens. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.

Alf.io handles the complete conference and event lifecycle from ticket distribution through check-in to financial reporting, built for organizers who refuse to surrender attendee data to third-party ticketing platforms like Eventbrite or Tito. Built on Java 17 with Spring Boot and PostgreSQL with row-level security policies, the project has earned over 1,500 GitHub stars from privacy-conscious event organizers across Europe and beyond. Payment processing supports Stripe for credit cards, Mollie for iDEAL, Bancontact, KBC/CBC, and Przelewy24, plus Revolut, PayPal, bank transfers, on-site collection, and configurable custom offline payment methods with localized instructions. Multi-tier ticket categories enable early bird, VIP, standard, and free registrations with promotional codes, group discounts, and waiting lists that automatically notify next-in-queue when cancellations occur. Customizable registration forms collect attendee data beyond standard fields, while EU VAT management validates tax IDs through the VIES web service and supports Italian e-invoicing with automatic PDF invoice generation attached to confirmation emails. The Alf.io Scan mobile app for iOS and Android performs QR code check-in at venue entrances, and the Alf.io-PI project provides Raspberry Pi-powered offline-capable check-in stations that form encrypted clusters for high-throughput badge printing at large events. Apple Wallet integration delivers digital passes via PassKit. The extensions system integrates with CRMs, accounting platforms, Slack, Telegram, and Mailjet. Multi-language support covers nine languages. Deploy via Docker with PostgreSQL. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. GPLv3 licensed.

Yoga studios, comedy clubs, choirs, and bands use Revel to sell tickets, memberships, and season passes from their own server with no platform fee. Studios and clubs sell monthly or yearly memberships through Stripe and offer series passes that cover a class pack, a course, or a season, with wallet cards that a door scan verifies. Venues design seat maps with sectors, individual seats, and accessible seats, and buyers pick seats on an interactive map while the seats are held at checkout. Bands and DJs sell their own shows with no promoter in between, set pay-what-you-can tiers, open presales to invitation-link holders, and export every buyer's name and email. Communities that vet who comes screen requests with questionnaires reviewed automatically, manually, or both, and keep private guest lists, invitation-only events, and a fuzzy-matched blacklist. Buyers check out a multi-tier cart without an account, using discount codes and fixed-price, free, or pay-at-the-door tiers. Tickets arrive as QR PDFs or Apple Wallet and Google Wallet passes, and door staff check guests in by scanning. Organizers run waitlists with time-limited offers, announcements, reminders, and a Telegram bot for RSVPs and invitations. Revenue and VAT reports export as XLSX or PDF, and VIES checks buyer VAT IDs. The web app speaks English, German, Italian, French, Spanish, and Portuguese. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.

Pretix powers thousands of events and millions of ticket sales through a fully brandable ticket shop with interactive seating plans, 30+ payment providers, and a mobile check-in app for venue entry management. With over 2,400 GitHub stars, it delivers what organizations need when they demand full control over attendee data and revenue rather than surrendering margins to Eventbrite or Ticket Tailor. Built with Python and Django on PostgreSQL with Redis and Celery, the ticket shop adapts to your colors, logo, and domain with responsive design. The graphical seating plan editor handles everything from small cinemas to large stadiums, letting buyers choose seats mapped to pricing categories. Payment providers connect through plugins including Stripe, PayPal, Mollie for iDEAL and Bancontact, SEPA direct debit, and bank transfer with automatic CSV import for payment matching. The voucher engine generates bulk discount codes with usage limits, quota reservations, and automated email distribution. Waiting lists automatically offer released tickets to the next registrant with expiration deadlines. A built-in mini-CMS hosts event descriptions, terms of service, and static pages directly in the ticket shop. Customer accounts enable repeat buyers to check out faster across events. The pretixSCAN mobile app performs QR code check-in on Android and iOS with offline capability. Embeddable JavaScript widgets integrate the shop into any website. Plugin architecture extends functionality with output formats, analytics, and Apple Wallet passes. Deploy via Docker with the pretix/standalone image alongside 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. AGPL-3.0 licensed.

Passive slide decks put audiences to sleep, which is why Claper turns any presentation into a two-way live session where every attendee can vote in polls, submit questions, and react in real time from their phone. Speakers upload existing PDF or PowerPoint decks directly into the web studio and interleave interactive poll, quiz, form, and web embed slides between their static pages without rebuilding presentations from scratch. Conference organizers and educators share a short join code or QR link so hundreds of participants can enter the attendee room instantly from any mobile browser without installing an app or creating an account. During the talk, the presenter console displays incoming audience questions sorted by upvote popularity, alongside moderation controls to approve, pin, hide, or mark inquiries as answered on the main screen. Live polling supports multiple-choice, rating scale, and open-text prompts that animate into real-time bar charts and percentage breakdowns as votes arrive, while timed quizzes grade participant responses automatically. Integrated real-time speech transcription generates live captions and searchable session transcripts so international and hearing-impaired attendees can follow every spoken word. Universities and corporate training teams connect Claper directly to Moodle or OpenID Connect identity providers via LTI 1.3 to synchronize student rosters, push quiz scores to gradebooks, and export complete CSV engagement reports after every session. 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.

If an assembly needs motions, amendments, speaker lists, and secret ballots on one shared screen, OpenSlides is the open-source web application that runs them. Before the meeting, administrators set up committees and meetings, import participants from CSV or connect a SAML identity provider for single sign-on, email invitations with login data, and sort people into groups with freely defined rights. Members file motions in an HTML editor, attach documents, gather supporters, and send them through customizable workflows with automatic numbering by category, and amendments and change recommendations attach to specific line numbers. Motions can be forwarded to other meetings. During the session the agenda reorders by drag and drop, and every item, motion, or election gets its own speaker list with countdowns, points of order, and recorded speaking time. Votes are open, secret, or nominal and run live for present participants in voting groups, with proxy delegation, vote weighting, multiple rounds, and Yes/No/Abstain options per candidate or list. Results appear against a chosen reference value on projectors, in PDF exports, or as individual tallies. Several projectors can show the current item, a lower third for the active speaker, and live results, and Autopilot guides participants through whatever is happening. A video livestream brings in remote attendees. Afterward, motions export to PDF, CSV, or XLSX. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.

What Doodle did before ads and paywalls took over: Rallly (three L's) lets you propose a few dates, share a link, and watch an availability grid fill in - no email threads, no forced accounts, no "$6.95/month to remove ads." The availability grid makes the winning slot obvious at a glance, comments on each poll keep the "I can do Tuesday if we start late" discussion attached to the decision instead of buried in chat, and email notifications fire as votes and comments arrive. When consensus lands, finalize the winning option and everyone gets notified. The stack is modern TypeScript - Next.js, tRPC, Prisma over PostgreSQL, Tailwind - with a clean, genuinely mobile-friendly UI, dark mode, and community translations in 10+ languages. Self-hosting means unlimited polls and unlimited participants with meeting data on your server rather than a scheduling SaaS. It pairs naturally with Cal.com: Rallly answers "which time works for everyone?", Cal.com handles "book a slot on my calendar." AGPL-licensed.

Hi.Events is an alternative to Eventbrite, Tickettailor, and Dice.fm, eliminating per-ticket platform fees entirely when self-hosted. Event organizers create fully brandable event pages supporting paid, free, donation, and tiered ticket types with recurring and multi-date scheduling, sold-out waitlists that automatically release tickets when spots open, and product add-ons with category organization. Stripe Connect integration processes payments directly to the organizer's bank account with instant payouts, while offline payment methods support cash and invoice scenarios. Promo codes offer fixed or percentage discounts with usage limits, expiry dates, and promo-gated hidden tickets for VIP access. QR code check-in enables fast door scanning with multiple check-in lists, scan logs, and real-time attendance tracking across entry points. Custom checkout questions collect attendee information beyond standard fields, with advanced search, filtering, CSV and XLSX export, full and partial refunds, and bulk attendee messaging. The analytics dashboard tracks daily sales, revenue, tax breakdowns, product performance, and promo code usage with exportable reports, while affiliate tracking assigns custom codes to promoters with tracked sales data. Multi-user roles control organizer permissions, automatic invoicing generates receipts, and the REST API ships with interactive OpenAPI documentation. 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.

Video meetings on your own domain, branded your way, with no per-host bill: PlugNmeet is a self-hosted web conferencing system that runs full meetings in the browser. The room covers HD video and screen sharing, a collaborative whiteboard that annotates PDFs and office files, a shared notepad, chat, polls, and breakout rooms. Classes use raise hand, waiting rooms, per-user locks, and quiz-mode polls; webinars stream out over RTMP to YouTube or take in an OBS feed. Every meeting can be recorded to MP4, joined by phone through SIP dial-in, and captioned, translated, transcribed, and summarized by an AI agent connected to your own provider. Moderators manage participants and permissions, optional end-to-end encryption keeps even the server out of the media, and plugins drop the same rooms into WordPress, Moodle, Joomla, or any LMS over LTI. Behind it, APIs and PHP or JavaScript SDKs create rooms and mint join tokens from your product. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. MIT licensed.

Used daily by millions of educators and learners in over 65 languages and embedded as the default virtual classroom in Moodle Cloud, Canvas, Sakai, D2L, Jenzabar, and Schoology — together comprising more than 75% of the worldwide learning management system market — BigBlueButton has been the leading open-source web conferencing platform for education since its creation at Carleton University in 2007. The platform delivers WebRTC-based real-time audio, video, and screen sharing with a tldraw v2-powered multi-user whiteboard featuring infinite canvas support, allowing multiple participants to annotate slides and draw simultaneously. Breakout rooms support up to eight concurrent groups with collaborative whiteboards enabled by default, and polling with customizable response types lets instructors assess understanding in real time. The built-in Learning Analytics Dashboard answers three questions at a glance: who is attending, who is participating, and who is learning based on poll responses, providing actionable engagement metrics without requiring webcam surveillance. Session recording captures audio, video, slides, chat, and whiteboard annotations for asynchronous playback on any device. The plugin architecture introduced in version 3.0 enables custom extensions, while IMS LTI 1.0 compliance allows integration with Blackboard, Desire2Learn, Pearson Learning Studio, and any conformant platform without custom code. The REST API enables programmatic session management, user authentication, and recording access for custom frontends like the included Greenlight application. Version 4.0 introduces LiveKit-based media and a redesigned interface. Running on a dedicated VPS on RepoCloud with guaranteed CPU, RAM, and SSD, full root SSH access, and a browser serial console. LGPL-3.0 licensed.

Apache OpenMeetings puts the whole meeting in the browser: cameras, a shared whiteboard, the agenda document, and recording controls, all running on your own server. Participants join rooms with audio and video, audio only, or video only, choose camera resolutions and devices, and present by sharing a screen or a single window at selectable quality. Moderators control the floor person by person: who may draw on the whiteboard, present, share or record the screen, mute others, or speak while everyone else stays muted. Multiple whiteboards hold drawings, text, clip art, and imported documents in PDF, office, and image formats, rescaling to fit every participant's screen, and boards can be saved into the drag-and-drop file explorer for the next session. Every meeting can be recorded with all audio streams exactly as heard, then downloaded as MP4 or played back in the integrated player, and the built-in calendar schedules rooms and sends invitations. Breakout rooms split classes and workshops into groups, polls gather decisions live, private and group chat runs beside the video, and telephone users can dial into rooms through the Asterisk SIP integration. 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.