PacketProfiler

PacketProfiler is a lightweight, client-side Fabric mod for Minecraft 26.2 that profiles packet frequency and Minecraft protocol-frame bandwidth in real time.

It is designed for mod developers, server administrators, technical players, and anyone investigating unusual network activity or bandwidth usage. No server-side installation is required.

Features

• Count incoming and outgoing packets by class-style name.
• Identify the busiest packet types during a capture.
• Measure protocol-frame bandwidth by direction and packet type.
• Display compact, readable reports directly in chat.
• Inspect selected packets using the sanitized PacketSniff tool.
• Tab-complete supported packet class names.
• Suggest the closest packet when a name is mistyped.
• Optionally save complete aggregate reports asynchronously.
• Remain effectively idle when no profiler is running.

Commands

Command	Description
/packetprofiler	Start or stop a packet-count capture.
/packetprofiler max [duration]	Capture every observed packet type. Defaults to 10 seconds.
/packetprofiler bandwidth [duration]	Measure incoming and outgoing protocol-frame bandwidth.
/packetprofiler bandwidth [duration] -verbose	Include every observed packet type in the bandwidth report.
/packetprofiler packetsniff <packetname>	Print sanitized fields from every matching packet until stopped.
/packetprofiler packetsniff	Stop the active PacketSniff.
/packetprofiler logging	Toggle persistent aggregate report logging.
/packetprofiler help	Display the in-game help menu.

Durations support h, m, and s. For example, 3h49m5s runs for 3 hours, 49 minutes, and 5 seconds.

Only one capture or PacketSniff can be active at a time.

Bandwidth measurement

PacketProfiler measures Minecraft protocol frames after transport decryption.

Measurements:

• include the frame’s VarInt length prefix;
• exclude Ethernet, IP, and TCP headers;
• separate incoming and outgoing traffic;
• attribute measured bytes to high-level packet classes where possible.

Packet observation is optional, non-cancelling, and fail-open. PacketProfiler does not modify, delay, resend, or cancel network traffic.

Privacy

Ordinary captures store only:

• packet class names;
• direction;
• counts;
• aggregate framed bytes;
• percentages;
• capture duration;
• peak packet rates.

PacketProfiler does not capture packet payloads.

PacketSniff is deliberately sanitized. Text, chat, NBT, item data, buffers, usernames, UUIDs, server addresses, credentials, tokens, signatures, and authentication material are redacted. PacketSniff output is chat-only and is never written to persistent reports.

Logging

Persistent logging is disabled by default. When enabled, full aggregate reports are written asynchronously under:

config/packetprofiler/

Requirements

• Minecraft 26.2
• Fabric Loader 0.19.3+
• Fabric API 0.156.0+26.2+
• Fabric Language Kotlin 1.13.13+kotlin.2.4.10+
• Java 25

PacketProfiler is a client-only mod and does not need to be installed on the server.

PacketProfiler is maintained by AI under human direction and review.