KnockbackSync
by Axionize
KnockbackSync is a Fabric library that recalculates player knockback on the server so hits land consistently for players with different connection quality.
What it does
Minecraft does not factor network latency into how the server judges a player's actions, so the server can receive outdated information that does not match a player's position on their own screen. On high-latency connections this gives varying knockback, which the author describes as the main cause of unfair PvP. The mod intercepts knockback calculations and adjusts them so the result matches what the client actually shows, reducing the disadvantage of a slow connection.
The mod measures each player's ping by sending ping packets and waiting for the matching pong. It tracks an estimated ping and a jitter value, which shows how much the latency varies over time. Two settings control the feature: knockbacksync.ping, on by default for players, and knockbacksync.status.self, which lets a player check their own status. Installation needs Fabric API. The mod is open source under the GNU General Public License v3.0 only and is published for Fabric across 51 release versions, 1.12.2 – 26.2.
Key features
Server-side knockback recalculation
Knockback is recalculated on the server to match what occurs on each client, with latency taken into account.
Ping measurement
Ping packets and pong responses measure each player's latency, with the last ping time shown in milliseconds.
Estimated ping and jitter
An estimated ping is derived from the reported platform ping, and jitter shows how much latency varies over time.
Self status check
A permission-controlled command lets a player see their own ping, estimated ping and jitter.
Compatibility
Latest build for each game version and loader.
26.x1 of 1 version with builds
1.21.x12 of 12 versions with builds
Only full game releases are shown. This mod publishes no snapshot builds.
Requirements
Dependencies declared by the latest file for each loader.
Required 1
Use cases
Competitive PvP servers
Server owners running combat minigames or PvP modes can use the mod so that knockback feels the same to players on fast and slow connections.
Who it’s for: Server owners running PvP servers, and developers who want to build on server-side knockback and latency handling. Paper, Spigot, Bukkit, Purpur and Folia are listed as server platforms the mod is also available for.
How it compares
Ping Viewer is a Fabric server-side mod for 1.21.4 – 26.2 under All rights reserved, and it is not open source. Tab Ping is a Fabric client-side mod for 1.20.4 – 26.1 under the MIT License, and it is open source. KnockbackSync is open source under the GNU General Public License v3.0 only and covers 1.12.2 – 26.2.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| KnockbackSync | Fabric | 1.12.2 – 26.2 | Not published | 2026-08-22 |
| Ping Viewer | Fabric | 1.21.4 – 26.2 | Server-side only | 2026-08-13 |
| Tab Ping | Fabric | 1.20.4 – 26.1 | Client-side only | 2026-03-25 |
Questions
Does KnockbackSync need Fabric API?
Which game versions have builds?
Can the ping feature be turned off?
In the catalog
KnockbackSync is one of 3,514 Library mods on ModsFinder, and one of 2,348 Library mods for Fabric. 13,894 mods support Minecraft 26.2.
More from Axionize
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What the author says
Tired of inconsistent knockback ruining your PvP experience? Our plugin recalculates knockback as if it were done clientside, leveling the playing field and ensuring every player enjoys a fair fight, no matter their connection quality. Minecraft doesn’t factor in network latency when determining a player's actions on…
Official listing
- Modrinth page
- modrinth.com/mod/knockbacksync
- Owner
- Axionize
- Published
- 2024-10-05
- Updated on Modrinth
- 2026-08-22
- Facts verified
- 2026-10-15