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Packet Spy project artwork

Modrinth · Minecraft mod

Packet Spy

A client-side Fabric mod that lets you inspect Minecraft network packets live through a simple web interface.

Choose a version Pick your version below, then grab the matching file.

Quick answer

Which Packet Spy release matches 1.21.9?

Updated last month
Best match for your filters 2.4+mc1.21.9-1.21.10
Game version 1.21.9, 1.21.10
Loader Fabric

Packet Spy 2.4+mc1.21.9-1.21.10 targets 1.21.9, 1.21.10 with Fabric. It must be installed on the client. Do not install it on the dedicated server. All 1 required mods have matching files.

Where it goes

Is Packet Spy required on the client, server, or both?

It must be installed on the client. Do not install it on the dedicated server.

Client Required
Dedicated server Not supported
Loader for this release Fabric
Required install it here Optional supported, not mandatory Not supported do not install here Source doesn’t say do not assume

This file is marked client-only.

Understand client and server requirements Read the Minecraft installation guide

What else does Packet Spy 2.4+mc1.21.9-1.21.10 need?

2.4+mc1.21.9-1.21.10 on 1.21.9. Every mod below is checked against that same setup.

All 1 required mods have matching files

Install Fabric API first. We found matching files for this game-version and loader setup.

Fabric API Needed by Packet Spy 2.4+mc1.21.9-1.21.10
required
Matching file found Matched file: [1.21.9] Fabric API 0.134.1+1.21.9

We only count dependency files that match this setup. A file for another loader does not fill the gap.

Before you install it

Add Packet Spy without breaking your instance.

Built for Packet Spy 2.4+mc1.21.9-1.21.10 on 1.21.9. Pick another file and the loader, install side or required mods may change.

  1. 01

    Stick to this file

    Use 2.4+mc1.21.9-1.21.10. It targets 1.21.9, 1.21.10 with Fabric; another release may have different loader, side or dependency requirements.

  2. 02

    Bring the mods it needs

    Install Fabric API first. We found matching files for this game-version and loader setup.

  3. 03

    Put it on the correct side

    It must be installed on the client. Do not install it on the dedicated server.

  4. 04

    Pick the file you checked

    Use the “Get this file” button beside 2.4+mc1.21.9-1.21.10. It opens that exact file at the source.

About this project

What does Packet Spy add?

PacketSpy is a client-side Fabric mod for viewing the network packets your Minecraft client sends and receives in real time.

Press F12 (can be rebound in settings) in-game to open the local web interface. From there you can search and filter packets, inspect their fields as JSON, sort packet traffic, mute noisy packet types, and export what you're looking at.

It works in both singleplayer and multiplayer and does not need to be installed on the server.

Features

  • Live incoming and outgoing packet viewer
  • Search and filter by packet type, direction and category
  • View packet contents as readable JSON
  • Mute packet types you don't care about
  • Packet grouping and traffic visualization
  • Dark and light themes
  • Local web interface
  • Optional LAN access if you want to view it from another device

PacketSpy supports Minecraft 1.21–1.21.11 and 26.1–26.3 using Fabric. Make sure to download the jar that matches your Minecraft version.

The web interface runs locally on your computer and LAN access is disabled by default.

Project description from Modrinth.

Pick your setup

Packet Spy by Minecraft version and loader

Choose the version and loader you play, then open the matching release.

17 available setups

Showing the newest 12 of 17 game versions. Older files are in the list below.

Check the dependencies, then try the file in a copied instance before changing a world you care about.

Recent files

Packet Spy versions and loaders

1 of 7 releases match
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Looking for an older file? The official Modrinth project page is in Resources.

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