AP Event Bus — Free Replicated Pub/Sub Event System for Multiplayer UE5

Balive
Fri, 27 Mar 2026 18:29:05 +0000
Product Discussion

Hey everyone,

I’m Michael from AfterPrime Systems. I’m sharing a free plugin that I built as part of a larger multiplayer gameplay suite.

AP Event Bus is a replicated pub/sub event system. One component on your GameState. Any actor publishes events by Gameplay Tag. Any actor listens by Gameplay Tag. Publishers and listeners never reference each other — fully decoupled.

I released this for free because I think every multiplayer project needs some version of this, and most people end up building one from scratch every time. If you find it useful, it’ll give you a sense of the architecture and quality standard across the rest of the AfterPrime suite.

WHY USE THIS INSTEAD OF ROLLING YOUR OWN

Client-to-server routing is automatic — one PublishEvent node works from any machine. No authority checks, no separate client/server functions.

Four delivery scopes: All (NetMulticast), OwnerOnly (Client RPC), ServerOnly, LocalOnly.

Late-join cache — register tags as persistent and late-joining clients automatically receive cached event state. Match phase changes, captured objectives, world state all sync correctly for players joining mid-game.

Two-tier delegate system — OnEventReceived (catch-all) and OnListenedEventReceived (filtered by tag). Use both simultaneously.

Blueprint helper library — GetEventBusFromGameState, PublishEventOnBus, MakeEventPayload. Convenience functions available in any Blueprint graph.

WHAT’S INCLUDED

C++ plugin with full source (Runtime module)

Blueprint helper library with 4 convenience functions

C++ demo character with input-driven examples across all four delivery scopes

Quick Start Guide + full API Reference + Changelog

TECHNICAL DETAILS

UE 5.4 – 5.7 supported

Zero external dependencies, no GAS

Server-authoritative, RPC-based replication (no replicated UPROPERTYs)

Single component on GameState

LINKS

Fab (FREE): AP Event Bus - Replicated Event Messaging System | Fab
Discord: AfterPrime Systems

PAID PLUGINS IN THE SUITE

If you like the Event Bus architecture, the paid plugins follow the same design:

AP Timer Suite — Replicated Timers + Threshold Events ($14.99): AP Timer Suite - Replicated Timers | Fab

AP Cooldown Suite — Replicated Cooldowns ($24.99): AP Cooldown Suite - Replicated Cooldowns System | Fab

AP StatusFX Suite — Replicated Status Effects ($24.99): AP StatusFX Suite - Replicated Status Effects & Buff/Debuff System | Fab

All standalone, all server-authoritative, all Gameplay Tag-keyed, all Blueprint-first with full C++ access.

Let me know if you have questions or run into anything. I’ll keep this thread updated with changes.

— Michael / AfterPrime Systems

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