{"data":{"slug":"mercure","name":"Mercure","tagline":"AGPL-3.0 SSE hub; homepage still says MIT","category":"comms","categoryName":"Comms","url":"https://mercure.rocks","github":"https://github.com/dunglas/mercure","pricing":"open-source","hook":"Mercure is the SSE hub whose marketing page has not caught up with its LICENSE file.","whatsGood":"LICENSE file is GNU AGPLv3. SSE hub: publish with POST, subscribe with EventSource. Caddy-based, Docker/Helm, Last-Event-ID replay. Official realtime path for Symfony. Self-host the Hub.","theCatch":"Homepage still says the Hub is MIT-licensed. The LICENSE file is AGPL-3.0 — print the file. SSE, not WebSockets, not Pusher protocol. Distinct from Socket.IO and Soketi. Cloud/Enterprise exist; do not invent prices. OSS self-host is the free path.","verdict":"AGPL SSE hub. Believe the LICENSE file, not the MIT line on the homepage.","addedAt":"2026-09-03","featured":false,"domain":"Comms","subSpecialty":"Realtime","capabilities":["sse","realtime"],"surfaces":["Self-host"],"ecosystem":["Go"],"licenseModel":"AGPL","githubStars":5304},"related":[{"slug":"livekit","name":"LiveKit","tagline":"Apache-2.0 realtime rooms, SFU, and agents"},{"slug":"chatwoot","name":"Chatwoot","tagline":"MIT-core support inbox you can self-host for $0/agent"},{"slug":"socket-io","name":"Socket.IO","tagline":"MIT realtime library with fallbacks, not a hosted product"},{"slug":"plunk","name":"Plunk","tagline":"AGPL-3.0 transactional email, workflows, and broadcasts"},{"slug":"centrifugo","name":"Centrifugo","tagline":"Apache-2.0 Go realtime server binary, not in-process Socket.IO"}],"links":{"self":"/api/gems/mercure","html":"/gems/mercure","markdown":"/gems/mercure.md","category":"/api/gems?category=comms","categoryPage":"/stacks/comms"}}