When added to a modpack ModpackInfo will do the following things:

It will generate a log file to the ./minecraft directory which contains information about each of the loaded mods. The information is sourced from the mods themselves. The format of the output file can be configured to text, XML, json, or BBCode.
If configured to do so a player will be sent modpack information via in-game chat when they log in. This information would have to be configured by the modpack authors prior to deployment.
Players will have access to a /modpackinfo command in-game. This command will retrieve additional information about the modpack that has been deployed.

Further information can be found on the Wiki.

Sample text file output:

Version: 1.0.1  
http://www.nothere.com  
Modpack Authors: OreCruncher  

Minecraft Coder Pack (mcp) Version 9.05  
Modding toolkit to decompile and deobfuscate the Minecraft client and server files.  
Credits: Made by the MCP team  
Website: http://mcp.ocean-labs.de/  

Forge Mod Loader (FML) Version 7.10.85.1291  
The Forge Mod Loader provides the ability for systems to load mods from the file system. It also provides key capabilities for mods to be able to cooperate and provide a good modding environment.   
Credits: Made possible with help from many people  
Authors: cpw, LexManos, Player  
Website: https://github.com/MinecraftForge/FML/wiki
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Modpacks

ModpackInfo is licensed MIT. This means that you are free to include in modpacks and there are no requirements about giving credit or linking pack to any page. However, if you feel compelled to give credit I won't mind. :)

Donations

If you wish to donate you can support me on Patreon.