Realtime tools

• SupabaseOpen-source Firebase alternative built on Postgres

  Free / OSS · Freemium · 113k GitHub stars

  VerdictThe Firebase alternative for developers who want real Postgres.

  CatchThe all-in-one convenience creates dependency. Complex queries hit performance limits. Self-hosting requires significant operational knowledge.

• ntfyHTTP pub-sub notifications you can curl from cron

  Free / OSS · Apache-2.0 · 35k GitHub stars

  VerdictThe notification CLI that is actually free. curl it from a cron job.

  CatchAnonymous topics are passwords — guessable names leak other people's alerts. Public ntfy.sh rate-limits; reserved topics need Pro. Dual license means you pick Apache-2.0 or GPLv2, not Apache-only.

• LiveKitApache-2.0 realtime rooms, SFU, and agents

  Free / OSS · Apache-2.0 · 21.7k GitHub stars

  VerdictApache-2.0 voice/video/agent runtime. Self-host is the free path; Cloud pricing is not confirmed here.

  CatchSelf-hosting an SFU is ops-heavy. Cloud Build pricing and free allowances are not confirmed here; check the vendor site. Do not assume Cloud is free.

• Socket.IOMIT realtime library with fallbacks, not a hosted product

  Free / OSS · OSS/MIT · 63.2k GitHub stars

  VerdictThe MIT socket library. Free as in you run it.

  CatchYou bring the host. Horizontal scale needs Redis (or equivalent) adapter. This is not LiveKit and not a managed pub-sub. CORS, sticky sessions, and polling surprises remain your bugs.

• ColyseusMIT Node multiplayer rooms with state sync

  Free / OSS · OSS/MIT · 7.4k GitHub stars

  VerdictMIT multiplayer rooms. Self-host is the free path; Cloud is paid from dollar one.

  CatchA server framework, not a renderer. Colyseus Cloud has no free tier — it starts at 15 USD/mo. Capacity depends on your code, not a marketed CCU cap.

• CentrifugoApache-2.0 Go realtime server binary, not in-process Socket.IO

  Free / OSS · Apache-2.0 · 10.9k GitHub stars

  VerdictApache-2.0 realtime binary. Free as in you operate the server.

  CatchYou run it. This is not Socket.IO in-process. Cloud/PRO pricing is not confirmed here — no invented Cloud prices. Ops, clustering, and Redis when you scale stay yours.

• YjsMIT CRDT library, not a hosted collab product

  Free / OSS · OSS/MIT · 23k GitHub stars

  VerdictThe MIT CRDT. Pair with Liveblocks for hosted rooms; this is the library, not the meter.

  CatchNot a product. No hosted SKU, no pricing page, no support SLA. You bring the network layer (Liveblocks, y-websocket, your own). Distinct from Socket.IO: CRDT merge, not event fan-out.

• MercureAGPL-3.0 SSE hub; homepage still says MIT

  Free / OSS · AGPL-3.0 · 5.4k GitHub stars

  VerdictAGPL SSE hub. Believe the LICENSE file, not the MIT line on the homepage.

  CatchHomepage 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; check their pricing page. OSS self-host is the free path.

• AnyCableMIT realtime for Action Cable with delivery guarantees

  Free / OSS · Freemium · 2.4k GitHub stars

  VerdictMIT Action Cable path. OSS tier is free; not Soketi, not Socket.IO.

  CatchDelivery guarantees + presence + Action Cable / multi-backend — not a Pusher-protocol server. Distinct from Socket.IO and Centrifugo. Pro and Managed exist; prices not reprinted here.

• Pion WebRTCMIT embeddable Go WebRTC library — not a rooms product

  Free / OSS · OSS/MIT · 16.9k GitHub stars

  VerdictMIT Go WebRTC library. Free to embed; not a rooms stack.

  CatchEmbeddable Go library — not LiveKit rooms product, not mediasoup C++/Node media server, not PeerJS browser-only P2P helper. You assemble signaling and any SFU-class topology yourself. Distinct from LiveKit, mediasoup, and PeerJS.

• Janus GatewayGPL-3.0 plugin-core WebRTC gateway (SIP, VideoRoom, streaming)

  Free / OSS · GPL-3.0 · 9.2k GitHub stars

  VerdictGPL-3.0 WebRTC gateway. Self-host free; commercial options exist — pitch the OSS core.

  CatchPlugin-core C gateway — not LiveKit/mediasoup opinionated rooms products. You pick plugins and ops the gateway. Distinct from LiveKit, mediasoup, PeerJS, and Pion.

• SocketClusterMIT Node pub/sub+RPC+JWT with SCC scale-out

  Free / OSS · OSS/MIT · 6.2k GitHub stars

  VerdictMIT Node realtime cluster. Self-host free; not Socket.IO alone.

  CatchNode pub/sub+RPC+JWT+SCC scale-out — not Socket.IO library-only, not Soketi Pusher-protocol, not Centrifugo Go hub, not NATS messaging, not AnyCable Rails WS. Distinct from Socket.IO, Soketi, Centrifugo, NATS, and AnyCable.

• Laravel ReverbMIT first-party Laravel WebSocket server

  Free / OSS · OSS/MIT · 1.6k GitHub stars

  VerdictMIT Laravel WebSockets. Free with your Laravel stack.

  CatchFirst-party Laravel WS — not Soketi Pusher-protocol, not Centrifugo Go hub, not AnyCable Rails, not Socket.IO library, not Mercure SSE. Distinct from Soketi, Centrifugo, AnyCable, Socket.IO, and Mercure.

• SockudoMIT Rust Pusher V1 edge + Protocol V2 recovery/history/push

  Free / OSS · AGPL-3.0 · 827 GitHub stars

  VerdictMIT Rust Pusher-compat with V2 durability. Not AGPL Soketi.

  CatchVs Soketi: Rust Pusher V1 edge + Protocol V2 recovery/history/mutable/push — not AGPL v7-only. Distinct from Soketi AGPL Protocol v7 drop-in. Self-host is the free path.

• ElectricApache-2.0 Postgres read-path sync; Cloud PAYG under $5 waived

  Free / OSS · Freemium · 10.4k GitHub stars

  VerdictApache-2.0 Postgres sync. Self-host free; Cloud hobby under $5 waived.

  CatchRead-path sync — not a full offline-write CRDT stack or a replacement for your mutation API. Vs PowerSync/Replicache: Postgres-native shapes + free reads on Cloud, not mobile SQLite product packaging. Pro Cloud starts $249/mo.

• PartyKitMIT realtime rooms on Cloudflare Durable Objects; pay CF Workers only

  Free / OSS · ISC · 1.3k GitHub stars

  VerdictMIT CF realtime rooms. Free software; hosting is Workers/DO billing.

  CatchVs Liveblocks/Yjs+Hocuspocus: room primitive on CF, not prebuilt comments/inbox SaaS. You pay Cloudflare Workers/DO usage at scale. Auth, persistence, and CRDT choice are yours. Post-acquisition roadmap rides CF.

• gathoMIT self-host WebSocket rooms toolkit; no Cloud product

  Free / OSS · OSS/MIT · 83 GitHub stars

  VerdictMIT self-host multiplayer rooms. Free forever; alpha install path - treat as early but real.

  CatchVs Colyseus, PartyKit, and socket.io: rooms+seats toolkit — not state-sync, not CF Durable Object rooms, not a general WS framework. Author says early/not done but in production today. Prefer GitHub package install; registry tag is pre-release only. Docs still maturing.

• TrysteroMIT serverless WebRTC rooms via Nostr/MQTT/BitTorrent/IPFS

  Free / OSS · OSS/MIT · 2.8k GitHub stars

  VerdictMIT serverless WebRTC matchmaking. Free forever; pick it when discovery without your own signaling stack is the point.

  CatchVs PeerJS, Colyseus, PartyKit, and Gatho: discovery+P2P data library — not a rooms product, not a state-sync game server, not Durable Object rooms, not a process-per-room toolkit, not a PeerServer you host. NAT/TURN still bites some networks even after signaling succeeds. You still own matchmaking UX, presence policy, and anything that needs a true authoritative server.

• MatchboxMIT/Apache-2.0 Rust/WASM P2P sockets for Bevy + GGRS

  Free / OSS · Apache-2.0 · 1.2k GitHub stars

  VerdictMIT/Apache-2.0 Rust P2P for Bevy/GGRS. Free forever; you still host signaling.

  CatchVs PeerJS, Trystero, and Colyseus: Rust/WASM P2P socket + signaling crates — not a JS-first rooms kit, not serverless Nostr/MQTT discovery, not an authoritative game-room framework. You still run matchbox_server (or your own signaling) so peers can find each other; NAT/TURN still applies. Bevy version pins matter (bevy_matchbox tracks Bevy releases).

• HoppscotchMIT web-first open-source API client ecosystem

  Free / OSS · OSS/MIT · 80.7k GitHub stars

  VerdictMIT API client. Free core + self-host; pick it when the browser is the client, Bruno when Git is the source of truth.

  CatchVs Bruno (git-native *desktop* collections as files): Hoppscotch is web/self-host first, not “collections are just commits” by default. Cloud/workspace features and self-host ops are the real product surface — Enterprise exists for orgs. Not a mock/monitor platform.

• NakamaApache-2.0 full game backend — auth, storage, matchmaking, chat

  Free / OSS · Apache-2.0 · 13.5k GitHub stars

  VerdictApache-2.0 game backend. Free OSS single-node path; cluster HA is Enterprise — not the free story.

  CatchVs Colyseus, Gatho, and PartyKit: full social/game server, not a rooms-only kit, not process-per-room WebSockets, not CF Durable Objects. Multi-node HA / cluster management is Nakama Enterprise proprietary — the free path is OSS single-node (or single-process) self-host; clustering is the commercial side. You still run Postgres/Cockroach and own ops.

• ohaMIT HTTP load generator with realtime TUI (hey-inspired)

  Free / OSS · OSS/MIT · 10.6k GitHub stars

  VerdictMIT HTTP load TUI. Free forever; hammer your own staging and watch the chart.

  CatchVs hey (simple Go hammer), vegeta/k6 (scripted/scenarios), and curl loops: oha is the *interactive TUI load* CLI, not a full performance suite with thresholds-as-code. No browser/Web Vitals story. Point it at staging you own — load tests are still an attack if aimed at someone else.

• PipecatBSD-2 voice and multimodal realtime agents (Daily)

  Free / OSS · BSD-2-Clause · 16.7k GitHub stars

  VerdictBSD-2 realtime voice-agent framework. Pipelines you own; media/model meters separate.

  CatchVs LiveKit Agents (already covered under LiveKit comms stack) and OpenAI Realtime / voice extras: Pipecat is the pipeline framework for voice agents, not the SFU product. Daily transport/cloud and third-party STT/TTS meters when you leave local mocks. Not a text-only MCP orchestrator.

• DozzleMIT realtime Docker/Swarm/K8s log UI

  Free / OSS · OSS/MIT · 14.7k GitHub stars

  VerdictMIT live container log UI. Lightweight tail vs full observability stacks.

  CatchVs Grafana/Loki, ELK, Datadog (full observability): Dozzle is lightweight realtime log UI, not metrics/traces/storage/retention. If the container is gone, so is the history Dozzle never kept. Pair with a real log backend when you need audit trails.

• UniverEmbeddable Office runtime where agents and humans share documents

  Free / OSS · Apache-2.0 · 22.7k GitHub stars

  VerdictApache-2.0 Office runtime for agent-plus-human workflows. Strong for embeddable Sheets-first experiences; budget for Pro if collaboration and richer Office features are core.

  CatchVs Design Studio AI and json-render: Univer is an embeddable Office runtime, not a generative design canvas or a UI-description renderer. The Pro tier is commercial for collaboration, import/export, charts, and related capabilities; the OSS packages do not mean every production feature is free. Docs and Slides are also less mature than Sheets, so validate the exact surface before committing.

• Agent Client ProtocolApache-2.0 LSP-for-agents: one protocol so any editor can talk to any coding agent

  Free / OSS · Apache-2.0 · 4.5k GitHub stars

  VerdictThe interoperability bet for coding agents — adopt it when you build an editor or an agent, not when you just want a chat UI.

  CatchA protocol, not an app — both the editor and the agent must implement ACP before you feel the benefit. Full remote/cloud agent support is still in progress. Schema artifact versions can move without changing wire compatibility, which matters if you generate SDKs from the JSON Schema. Vs MCP (tool/server protocol for model context): ACP is the editor↔agent session protocol; they solve different layers and often ship together.

• AppwriteBSD-3-Clause backend: auth, database, storage, functions

  Free / OSS · BSD-3-Clause · 57.7k GitHub stars

  VerdictA complete Firebase-style backend you can actually self-host — worth it if you want one SDK for auth, data and files.

  CatchSelf-hosted Appwrite is a stack of many Docker containers, so plan for upgrades, backups and monitoring yourself; major-version upgrades have migration steps. You are buying into Appwrite's APIs and permission model, which makes leaving harder than with plain Postgres. The managed Appwrite Cloud is a separate commercial offering.

• DashyMIT customizable homelab dashboard with widgets

  Free / OSS · OSS/MIT · 26.8k GitHub stars

  VerdictPick Dashy if you want to tweak every pixel of your dashboard from the browser.

  CatchIt overlaps heavily with Homepage; Dashy leans toward UI customisation, Homepage toward service widgets. The Vue frontend is heavier than minimal dashboards like Glance or Homer. Status checks are simple pings, not alerting.

• Tile38MIT in-memory geospatial database and geofencing server

  Free / OSS · OSS/MIT · 9.7k GitHub stars

  VerdictThe quickest way to add live geofencing — Redis-style simplicity for location data.

  CatchIt is mostly a one-maintainer project, and releases are a few a year. Data must fit in memory. It is a specialised geofencing engine, not a general GIS database; for complex spatial SQL, PostGIS is the tool.

• KubetailApache-2.0 real-time log dashboard for Kubernetes workloads

  Free / OSS · Apache-2.0 · 1.8k GitHub stars

  VerdictA much nicer `kubectl logs -f` for whole workloads.

  CatchIt reads what the cluster still holds, so it does not replace a log store for history or search across days. Large clusters with chatty workloads can strain the API server. Still pre-1.0.

More with this tag (7)

• mitmproxy — MIT interactive TLS-capable intercepting HTTP proxy
• Yaak — MIT desktop API client for REST, GraphQL and gRPC
• Artillery — MPL-2.0 load testing for HTTP, WebSockets and browsers
• ws — MIT fast, tested WebSocket client and server for Node
• PeerJS — MIT browser P2P WebRTC with free cloud or self-host signaling
• Convex — Reactive TypeScript backend with real-time sync
• Liveblocks — Hosted collab rooms; Free $0 pauses at the cap