Turn slides into a live conversation.

The open-source, self-hostable alternative to Mentimeter, Slido and Wooclap.
Add Q&A, polls, quizzes, forms, live captions and reactions to the slides you already have.
Your audience joins from their phone: no app, no account.

Try it free · Self-host · Documentation · Website · Discord

_{Used by 7,000+ speakers at teams and institutions like CERN, Red Hat, KU Leuven, TU München and Deutsche Telekom (claper.co).}

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⚡ Get started

Pick the option that fits. The code is the same in both.

	☁️ Claper Cloud	🏠 Self-hosted
Setup	None, sign up and present	One docker compose up
Price	Free up to 10 attendees, then pay per event	Free, no attendee limit
Data	Hosted in the EU 🇪🇺	Stays on your servers
Updates	Handled by the Claper team	You decide when
	Try Claper for free →	Run it yourself ↓

🎯 How it works

1. Upload your deck. PDF, PPT or PPTX. No new slide editor to learn.
2. Add interactions. Polls, quizzes, forms, web content and live captions, attached to any slide.
3. Share the code. Attendees scan the QR code or type the event code on their phone.
4. Present. Responses, questions and reactions appear live on your slides and in your presenter view.
5. Follow up. Export messages, results and transcripts as CSV.

✨ Features

💬 Q&A and messages Attendees post questions and comments, named or anonymous Sort questions by popularity, pin the best ones, reply in-thread Show messages on the big screen or keep them private Moderation: delete messages, ban attendees, show pinned only 📊 Polls, quizzes and forms Live polls with results revealed on your slides Scored quizzes with correct answers and per-attendee results Feedback forms to collect structured answers Reactions (👏 ❤️ 💯 🙌) on the slide, in real time 🎙️ Live captions Real-time transcription displayed to the audience Searchable transcript kept and exportable after the talk Powered by Mistral, using your own API key

🖥️ Presenting Separate presenter and manager views, synced in real time Embed YouTube, Vimeo, Canva, Google Slides or any web page Keyboard navigation, drag-and-drop ordering Co-host with facilitators 🎓 Education and LMS LTI 1.3 integration with Moodle and other compatible LMS Quiz scores sent back to the LMS gradebook Export quizzes in QTI format 🔐 Built for organizations SSO with any OpenID Connect provider, or SSO-only by disabling password login Admin panel: users, roles, events, OIDC providers, audit log Local or S3-compatible storage, SMTP or Postmark email Official Docker image 10 languages: 🇬🇧 🇫🇷 🇩🇪 🇪🇸 🇳🇱 🇮🇹 🇭🇺 🇱🇻 🇸🇪 🇯🇵

🤔 Why Claper

• Own your data. Audience questions and votes can be sensitive. Self-host Claper and keep them on your infrastructure.
• Keep your slides. Present your existing PDF or PowerPoint deck instead of rebuilding it in another tool.
• No per-seat subscription. Self-hosting is free, and cloud plans are priced per event.
• Open source, for real. AGPL-3.0, developed in the open since 2022, with a public changelog.
• Real-time by design. Built on Elixir and Phoenix LiveView, a stack made for many concurrent live connections.

Comparing tools? Read Claper vs Slido, Mentimeter, Wooclap and AhaSlides.

🏠 Self-host in 2 minutes

Requirements: Docker with Compose.

git clone https://github.com/ClaperCo/Claper.git && cd Claper
cp .env.sample .env

# Generate a unique secret. Keep it: Claper uses it to encrypt stored settings.
sed -i.bak "s|^SECRET_KEY_BASE=.*|SECRET_KEY_BASE=$(openssl rand -base64 48)|" .env

docker compose up -d

Open http://localhost:4000 and sign in with the default admin account:

Email	Password
admin@claper.co	claper

Important

Change the default password right after your first login. To serve Claper on a public domain, set BASE_URL in .env and put it behind HTTPS (Traefik example).

Next steps

• Configuration reference: storage, email, sign-up, legal links, reverse proxy
• Single sign-on (OIDC)
• LMS integration (LTI 1.3)
• Updating Claper

🧱 Built with

Phoenix LiveView for real-time UI, PostgreSQL for storage, Oban for background jobs.

🤝 Contributing

Contributions of all sizes are welcome: bug reports, features, docs and translations.

1. Fork the repository and create a branch from dev
2. Set up your environment with the development guide
3. Open a pull request against dev

Read CONTRIBUTING.md for details, including how to add a new language. Not sure where to start? Browse open issues or ask on Discord.

💬 Community and support

• 💬 Discord: questions, ideas and help from the community
• 🐛 GitHub Issues: bug reports and feature requests
• 📖 Documentation: usage and self-hosting guides
• 🟠 r/claper · 𝕏 @alxlion_ (founder)
• 🔒 Security issue? Do not open a public issue, follow the security policy

If Claper helps you, a ⭐ helps others find it. You can also sponsor the project.

📄 License

Claper is licensed under the GNU Affero General Public License v3.0.