Packet Spy
PacketSpy is a network debugging tool for Minecraft. It intercepts and logs packets sent (TX) and received (RX) by the client. It features a local web interface (hosted via Java-WebSocket) that allows users to view packet traffic in real-time.
Screenshots
About this Mod
PacketSpy V2.0
This is a mod made to debug packets and log packets being sent and received by the client. It will host a website using Java WebSockets and host it on localhost:8887. It is not fully working now. For example, it says field_xxxx, where xxxx is numbers. I need to fix that ASAP, but yea, it's just a small mod to look at packets.
Available Versions
How to Install Packet Spy on Your Server
Order Server
Order a Minecraft Java server with at least 3 GB RAM (4 GB recommended).
Set fabric Loader
In the panel under "Egg", select the fabric loader and matching Minecraft version (1.21.5).
Install Mod
Open the mod browser in the dashboard and search for "Packet Spy". Click "Install" – done! Alternatively, upload the .jar via SFTP to the /mods folder.
Compatibility
Mod Loaders
Minecraft Versions
1.21.5, 1.21.4, 1.21.3 (+3 more)
Server-side
✗ UnsupportedRecommended RAM
4 GB(min. 3 GB)Frequently Asked Questions
Packet Spy server crashes on startup – what to do?
Most common cause: wrong fabric version or insufficient RAM. Check the server log (latest.log) for "OutOfMemoryError" or "Mixin" errors. With Mado Hosting: ensure at least 3 GB RAM is allocated and the loader matches the mod version (1.21.5). You can switch loaders with one click in the panel.
Is Packet Spy compatible with fabric?
Packet Spy officially supports fabric for Minecraft 1.21.5, 1.21.4, 1.21.3. The Mado dashboard automatically detects incompatible loader combinations.
Server lagging with Packet Spy – how to optimize performance?
Recommended RAM: 4 GB (per 8 players). Use /spark profiler to check if Packet Spy consumes the most tick time. Common fixes: reduce server view-distance to 8-10, install "performant" or "starlight" as supplementary mods on Forge. With Mado Hosting, your server runs on NVMe SSDs with dedicated CPU cores for minimal latency.
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Rent Modded Server
Install Packet Spy with just one click on your server.