FastPubSub

Real-time messaging over measured low-latency paths

Looking for the Python FastPubSub library? Check it out here.

This project is currently under development

Real-time message delivery over measured low-latency paths

For latency-sensitive real-time apps where direct Internet routing is sometimes suboptimal.

FastPubSub routes around overloaded interconnects and BGP detours in real time to keep delivery fast and stable, especially across regions, ISPs, mobile networks, and difficult enterprise edges.

10-15%

of measured routes show stable latency improvement.

5-25 ms

typical win on bad paths where direct routing is suboptimal.

Best fit

Cross-region traffic, mixed ISPs, mobile users, and stressed interconnects.

Real-world route: Tokyo ➔ Frankfurt

Map view (Europe to Asia corridor) Tokyo AS-Pacific Frankfurt EU-Central 220 ms FastPubSub Relay 240 ms Direct Internet (BGP Detours)

Improvement: 20 ms (avoiding congested peering)

Key Features

Rust Powered

Built entirely in Rust for high performance, memory safety, and low overhead.

Latency Routing

Our relays dynamically route packets based on real-time latency measurements (RTT), not hop count.

Overlay Network

Uses QUIC over UDP between relays to form an overlay mesh that can route around BGP detours and congested interconnects.

WebSocket API

Easy integration for clients via standard WebSockets. Logical channels instead of raw TCP streams.

Easy Integration

Start coding in minutes with our lightweight SDKs for major languages. No complex configuration required.

Standard Protocols

Built on open standards: WebSocket for edge connectivity (QUIC planned for clients) and QUIC for the relay backbone.

Primary ICP

Multiplayer and Real-time Applications

For state updates, session coordination, and user-facing interactions where jitter and unstable routes quickly affect user experience.

Cross-region Event Delivery

For workloads that move events between regions and need predictable delivery when direct Internet routing quality changes over time.

Latency-sensitive Fan-out

For channels that deliver the same event to many listeners and need lower-latency paths across mixed ISPs, mobile networks, and congested interconnects.

Engineered for Performance

Engineer note: WebSocket edge (QUIC planned) · QUIC relay backbone · Online-only fanout (no persistence)

Smart Overlay vs BGP

BGP is built for reachability, not speed. It can pick longer or congested routes. Our relays continuously measure RTT, jitter, and loss. If a path degrades, we recompute routes in seconds and steer traffic to a better hop.

No Storage = Speed

Pure fire-and-forget delivery. No disk persistence means fewer moving parts and no storage bottlenecks—messages flow from Writer to Listener without hitting a database.

No Blocking Queues

FastPubSub is message-oriented, not stream-oriented. We don't enforce global ordering across a channel, so there is no single serialized queue that every message must wait behind. Each subscriber has independent flow control—slow listeners won't stall fast ones.

Distributed Routing

Messages are forwarded through the relay fabric and fanned out near listeners, avoiding unnecessary central bottlenecks.

Developer Friendly

Drop-in SDKs. WebSocket today, QUIC for clients planned. QUIC relay backbone. Simple Pub/Sub API. Focus on your app logic, not networking code.

High Fan-out Design

Designed for many-to-many communication and high fan-out delivery. Practical limits depend on route quality, message size, and workload patterns.

What It Is — and What It Isn't

What FastPubSub is

  • Real-time relay fabric for low-latency fanout across regions
  • Message-oriented: fire-and-forget delivery up to 64 KB
  • Overlay mesh that probes paths and routes around congestion
  • Designed for live signals, cross-region reachability, and large audiences

What FastPubSub is not

  • Not a message queue (no persistence, no replay, no ordering guarantees)
  • Not Kafka, not RabbitMQ — no durable log, no consumer groups
  • Not a CDN — we move small messages, not large objects
  • Not a VPN — we route application-level messages, not raw IP packets

MVP Status: Working End-to-End

The core is operational: QUIC overlay mesh, latency-based Distance Vector routing, and access ticket authentication are all working. We are hardening these components and preparing for the first external testers.

New: dashboard.fastpubsub.com is live — a real-time monitoring dashboard showing our overlay network, latency savings, and network anomalies on a world map. We are also preparing the first SDKs for easy integration.

Read the full update

How It Works

1. Connect

Clients (Writers/Listeners) connect to our relays via WebSocket. Authentication and channel logic happen here.

2. Smart Routing

The message enters the network. Our relays use Distance Vector routing with latency metrics to forward data through a lower-latency measured path available at that moment.

3. Delivery

Data reaches the destination relay and is pushed to subscribed Listeners immediately.

Ready to build more responsive real-time apps?

Join our early access program and start routing around the public Internet's traffic jams.