Fabric Packet Logger
by HelixCraft
Fabric Packet Logger records the network packets that pass between a client and a server, including their full NBT and Component data, so they can be read and studied.
What it does
The mod captures traffic in both directions: incoming S2C packets such as inventory updates and entity spawns, and outgoing C2S packets such as clicks and movement. Packets are covered across the protocol phases, and the logger can show them in a readable, truncated form when the full data is not needed.
Which packets are logged is chosen in the config screen, opened with F6, through a dual-list selector. The selector reads the packet types from the game's PacketType registries when it loads, so the list follows the version in use. Fabric API is required. The mod is client-side only, and it is released under the MIT License as open source for 26.2, with 16 release versions 1.21 – 26.2 and a latest file of 1.2.3+26.2.
Key features
Full NBT and Component capture
Captured packets keep their full NBT and Component data, so the exact contents of a transmitted stack or entity can be inspected.
Two-direction logging
Both S2C and C2S packets are recorded, covering server-to-client updates and client-to-server actions.
Dual-list packet selector
An F6 config screen lets players pick which packet types to log from a list built from the game's PacketType registries.
Readable output
Packets can be shown in a truncated form that is easier to scan than the complete data.
Container inspection
Inventory contents are shown in full with their NBT and Component data, and that data can be copied out.
Gallery
Compatibility
Latest build for each game version and loader.
26.x4 of 4 versions 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
Who it’s for: Mod developers, researchers and players who want to understand Minecraft's network protocol. The mod is client-side only, so logging runs on the player's own client and the server needs nothing added.
How it compares
Fabric Packet Logger is client-side only, open source under the MIT License, and released for 1.21 – 26.2. mc-traffic-control is also a client-side, MIT-licensed Fabric mod, but its files cover 26.2 only. Packet Ninja is client-side only and open source under the GNU Lesser General Public License v3.0 only, with files for 1.21.8 – 1.21.11.
| Mod | Loaders | Game versions | Environment | Updated |
|---|---|---|---|---|
| Fabric Packet Logger | Fabric | 1.21 – 26.2 | Client-side only | 2026-08-13 |
| mc-traffic-control | Fabric | 26.2 | Client-side only | 2026-09-16 |
| Packet Ninja | Fabric | 1.21.8 – 1.21.11 | Client-side only | 2026-03-28 |
Questions
Does Fabric Packet Logger need Fabric API?
Does the server need Fabric Packet Logger?
How are packets chosen for logging?
In the catalog
Fabric Packet Logger is one of 8,499 Technology mods on ModsFinder, and one of 4,201 Technology mods for Fabric. 13,894 mods support Minecraft 26.2.
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What the author says
A deep packet logging mod for Minecraft Fabric that captures all network traffic ( S2C and C2S ) with full NBT/Component data. All packets are loaded dynamically from the game's PacketType registries and are selectable in the config screen's dual-list selector. Both S2C (Server → Client) and C2S (Client → Server)…
Official listing
- Modrinth page
- modrinth.com/mod/fabric-packet-logger
- Owner
- HelixCraft
- Published
- 2026-01-05
- Updated on Modrinth
- 2026-08-13
- Facts verified
- 2026-10-15