Cactus Comments is a federated comment system for the open web powered by the Matrix protocol, designed for website owners seeking privacy-respecting, decentralized commenting solutions.

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🚀 Overview

Cactus Comments is an open-source, embeddable comment system that uses the Matrix protocol to provide federated discussions on any website. It allows users to post and read comments directly in the browser or via popular Matrix clients like Element, without relying on centralized servers that track personal data or insert ads.

Unlike traditional systems like Disqus or Facebook Comments, Cactus leverages Matrix's decentralized architecture, where comment threads are Matrix rooms accessible across federated homeservers. Publishers can use public servers or self-host, ensuring full control and interoperability.

Answer these questions:

• What problem does this project solve? Traditional comment platforms are proprietary, data-hungry, and prone to censorship or downtime; Cactus solves this with open federation and privacy by design.
• Who is it built for? Bloggers, static site generators (Hugo, Jekyll), and any web publisher wanting libre comments.
• Why did you build it? To bring decentralized real-time communication to the static web, empowering users and creators with standards-based tools free from corporate silos.

Keep it human and honest.

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✨ Key Features

• Embed anywhere (what it does and why it matters): Simple JS + CSS snippet integrates into static or dynamic sites, enabling instant federated comments without backend changes.
• Privacy-respecting federation: Users log in via any Matrix server, keeping data control decentralized and ad-free.
• Matrix client compatibility: Seamlessly continue discussions in Element, FluffyChat, or 50+ clients.
• Self-hostable: Run your own instance on Matrix Synapse for full sovereignty. Optional: Multiple sections per site via commentSectionId.

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🛠 Tech Stack

• Frontend: Elm (compiles to vanilla JS)
• Backend: Python (Matrix Application Service)
• Database: PostgreSQL (standard for Matrix Synapse)
• Auth: Matrix federation
• Hosting: Self-hosted VPS/Docker or public cactus.chat servers

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👥 Who Is This For?

This project is useful for:

• Developers who want to ___ add federated comments to JAMstack or static sites without vendor lock-in
• Teams looking for ___ privacy-focused discussion tools integrable with open protocols
• Indie makers building ___ blogs or portfolios needing lightweight, decentralized engagement

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📸 Screenshots / Demo

• Live demo: https://cactus.chat/demo
• GitLab: https://gitlab.com/cactus-comments

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🔥 Project Status

• 🟡 Maintained

Last updated: 2026-03-24

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❓ FAQ

Is this project free?

Yes — Completely free and open source (LGPLv3 for client, AGPLv3 for backend). Use public servers or self-host. (Explain briefly.)

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Is the source code available?

Yes — link to repository https://gitlab.com/cactus-comments (main repos: cactus-client, cactus-appservice)

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Can I contribute?

File bugs/feature requests on GitLab issues, submit merge requests, or discuss in the Matrix room. Volunteers welcome!

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📬 Contact & Links

• Website: https://cactus.chat
• GitLab: https://gitlab.com/cactus-comments
• Twitter/X:
• Matrix: https://matrix.to/#/#cactus:bordum.dk

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