Use 3.2.0 for Minecraft 1.7.2/1.6.4/1.6.2/1.5.2/1.4.7 and older

Certain tasks are impossible to perform with the standard Bukkit API, and may require working with and even modify Minecraft directly. A common technique is to modify incoming and outgoing packets, or inject custom packets into the stream. This is quite cumbersome to do, however, and most implementations will break as soon as a new version of Minecraft has been released, mostly due to obfuscation.

Critically, different plugins that use this approach may hook into the same classes, with unpredictable outcomes. More than often this causes plugins to crash, but it may also lead to more subtle bugs.

Up-to-date developer builds of this project can be acquired at my Jenkins server. These builds have not been approved by the BukkitDev staff. Use them at your own risk.


Please create a ticket with as much information as possible if you experience a problem that has not already been reported. Comments with a huge stack trace will be deleted.

If you need help with the API, please use the developer support forum. If your question cannot be made public for whatever reason (including security bugs), send me a personal message instead.

For server operators

Just download ProtocolLib from the link above. It doesn't do anything on its own, it simply allows other plugins to function.


Source code for a bunch of example programs that use ProtocolLib can be found at this thread on the main support forum.

You may also be interested in PacketWrapper, a library that makes it possible to modify a packet without having to decompile the Minecraft source code.

Finally, for the more advanced users who want to use ProtocolLib if present, but still fall back on their own packet listening system, I recommend taking a look at this thread. I explain where and how to inject code into CraftBukkit in order to intercept sent and received packets yourself.

Maven repository

If you're using Maven, you'll be able to automatically download the JAR, JavaDoc and associated sources from the following repository:

    <name>Comphenix Repository</name>
<!-- And so on -->

This repository contains ProtocolLib, TagHelper and BlockPatcher. You can add any of them as a dependency like so:




Main administrative command. Supports the following sub-commands:

  • config: Reload the configuration file.
  • check: Check for new versions on BukkitDev.
  • update: Check for new versions and automatically download the JAR. The server must be restarted for this to take effect.
  • timings: Toggle measuring the amount of CPU time spent by each plugin. See here for more information.
  • listeners: Display what plugins are using ProtocolLib, and the packet types they are intercepting.

All of these commands require the permission protocol.admin.


/protocol update


Add or remove a debug packet listener. This is useful for plugin authors who just wants to see when a packet is sent, and with what content.

Sub commands:

  • add: Add a packet listener with a given packet ID.
  • remove: Remove one or every packet listener with the given packet IDs.
  • names: Print the name of every given packet ID.

Parameters (in order):

  1. Connection side: Either client or server.
  2. Multiple ID ranges: Can be a single packet ID like 14, or a range like 10 - 15. Defaults to 0 - 255 if not specified.
  3. Detailed: If TRUE, prints the full packet content.


/packet add client 10-13 true

Remove all listeners:

/packet remove client
/packet remove server

Note that this command should rarely be used on a production server. Listening to too many packets may crash the server.


The filter system (introduced in 2.4.1) uses the built in JavaScript interpreter in JVM 6 (Rhino) to extend the packet command with filtering capabilities - it is now possible to, say, only print entity metadata packet events (packet add server 40) for a given entity ID:

> packet add server 40 true
Added listener ListeningWhitelist{priority=MONITOR, packets=[40]}
> filter add entity_filter 40
Enter filter program ('}' to complete or CANCEL):
function(event, packet) {
>   return packet.a == 1000; 
Added filter entity_filter.

This should be much more convenient than having to compile a test plugin and reload the whole server. Note that this feature is disabled by default for security reasons. To enable it, add "debug: true" to config.yml.


A small set of configuration options are available:

Global section



auto updater.notifytrueInform any player with the permission when a new version of ProtocolLib is out.
auto updater.downloadtrueAutomatically download and install the newest version of ProtocolLib. The installation will take effect when the server restarts.
auto updater.delay43200The number of seconds between each check for a new update.
auto updater.last0This simply records the last time (in seconds since 01.01.1970) an update check was performed. Set it to 0 to force a new update check.
metricstrueIf TRUE, ProtocolLib will publish anonymous usage data to Set it to FALSE to opt-out.
background compilertrueIf TRUE, ProtocolLib will try and improve performance by replacing reflection with compiled code on-the-fly.
ignore version checkNoneForce ProtocolLib to start for a specified Minecraft version, even if it is incompatible.
suppressed reportsNoneIf any error or warning report is present in this list, they will not appear in the console or the log.

For more information, take a look at the default configuration file.

Tutorial for developers

See this page for more information.


One of the main goals of this project was to achieve maximum compatibility with CraftBukkit. And the end result is quite good - in tests I successfully ran an unmodified ProtocolLib on CraftBukkit 1.8.0, and it should be resilient against future changes. It's likely that I won't have to update ProtocolLib for anything but bug and performance fixes.

How is this possible? It all comes down to reflection in the end. Essentially, no name is hard coded - every field, method and class is deduced by looking at field types, package names or parameter types. It's remarkably consistent across different versions.

Plugins that appear to be compatible

Plugins known to be compatible

  • SpoutPlugin

Plugins using ProtocolLib

Inactive projects

Please let me know if you want me to add your plugin to this list. :)


This plugin uses MCStats to generate and publish anonymous aggregate usage statistics, but you can easily opt-out by setting metrics in config.yml to false.

If enabled, the following is sent every ten minutes:

  • Metrics revision version (currently 6).
  • Server's GUID
  • Players currently online (not max player count)
  • Server version string (the same version string you see in /version)
  • Current version of ProtocolLib
  • The name of every plugin that registers a packet listener in ProtocolLib.


I would like to thank everyone who has donated to ProtocoLib. I really appreciate it. :)



ProtocolLib Statistics

Note: Create a ticket if you're having problems. Don't post stack traces in the comments.

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  • Avatar of lme999 lme999 Dec 03, 2013 at 14:12 UTC - 2 likes

    @Seaboiii: Go

    I agree completely, if you guys want him to update faster, maybe donate a few $$. Don't just sit here saying please update, there was ALOT of code changed in this update that he has to get up to date with.

    === I'm looking for a private plug-in developer for my server. Interested? PM me! === Hybrid Minecraft Mini-games server.

  • Avatar of TheFrecyboy TheFrecyboy Dec 03, 2013 at 13:31 UTC - 2 likes

    Please Update on 1.7.2

    My Server Mein Server

  • Avatar of Archmohaa Archmohaa Dec 03, 2013 at 06:26 UTC - 0 likes

    @chsedv @defineci00 @inventivetalent @xiTzJardix

    Cool your jets turbo

  • Avatar of CommodoreAlpha CommodoreAlpha Dec 03, 2013 at 04:14 UTC - 0 likes

    Man, times like these I wish I could donate, but I'm just a minor (legally). Perhaps one day in the future, I'll make it up to you somehow. (I know there's no obligation, of course, but your constant dedication and friendly, understandable responses - even in the face of "those" kinds of comments - are simply astonishing.) Keep up the awesome work; I hope you endure and persevere through even the worst of crap Mojang may throw at you (whether the crap is intentional or not).

    @bergerkiller: Go

    Lo and behold, the comments right after yours reaffirm your statement. But I think it's become an internet norm where people don't read, which begs the question that if people don't read, how do they write? I don't think there's an answer to this, anyhow.

    Sure, I'd love to include my server IP here. But it's under construction, and I wouldn't want to get sued for players wandering inside and getting hit by a random beam of steel floating about. And no, I doubt plugins would make very good lawyers either. I've never seen a plugin that forced you to sign a contract do so well.

  • Avatar of Seaboiii Seaboiii Dec 03, 2013 at 01:24 UTC - 0 likes

    @DerekZil: Go

    Correct. What does saying "Please update" give any benefits to him? We would rather want a more stable Protocollib rather than a *hitty one. Give him a break ppl.. What if he quits doing Protocollib, all of us can't do anything. Saying "Please Update" is really useless. Doesnt benefit him at all. Why not give him words of encouragement instead?

  • Avatar of DerekZil DerekZil Dec 02, 2013 at 22:11 UTC - 0 likes

    Everyone stop asking for an update!

    He is in the process of fixing it. "Keep your useless comments in your pocket."

    Insanity Realms Website

  • Avatar of xiTzJardix xiTzJardix Dec 02, 2013 at 21:27 UTC - 0 likes

    Please update!


  • Avatar of inventivetalent inventivetalent Dec 02, 2013 at 19:31 UTC - 0 likes

    Please Update to 1.7.2

    Website | Plugins | YouTube | IRC | Bug Report BFAK:90886201,de707d7ec51153e8861caf53b15df86dd75333d2e62020fc98bb93f5e2015526


  • Avatar of defineci00 defineci00 Dec 02, 2013 at 19:21 UTC - 0 likes

    Update pls :/

  • Avatar of MetalGearDaner MetalGearDaner Dec 02, 2013 at 19:12 UTC - 0 likes

    Yeah, Protocol crashes with 1.7.2 :S I hope 1.7.2 protocol build will be available soon



Date created
Oct 05, 2012
Last update
Apr 17, 2014
Development stage
  • enUS
GNU General Public License version 2 (GPLv2)
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