If you've downloaded this before 3/17/19, you must redownload the patcher.
Installation instructions: Download the baseedit from MinecraftForums, and use the jar file I provided to "modify" the baseedit. Then you install by using the baseedit instructions on MinecraftForums.
You probably need Java 8 to do this.
If you would like to use this with LiteLoader, simply patch the .litemod file. It will say "4 out of 5 patchers" because the ClientBrandRetriever patcher isn't needed for the liteloader version. The patcher will work fully on liteloader despite what it says, but there is a chance that the server will block liteloader itself.
Note: If you get the following error when launching, relaunch with the launch button. (above "launch offline") (MultiMC only)
If you see an error in the output, make sure that
-Your WDL version is directly from the offical download link (https://github.com/Pokechu22/WorldDownloader/releases)
-Your WDL version is not already modified
-You selected the right WDL version (versions not from pokechu22 are not supported as there is no way to detect them)
Otherwise, PM me. You can try older releases of WDL to see if it works.
Note that all 5 patchers (4 with liteloader) should be fully working if you use the patcher on a unmodified version. If it isn't the case, it is an error. PM me for that.
How I Patch WDL:
The first step is to delete ClientBrandRetriever.class from the WDL mod. This prevents the client brand from being sent as "WorldDownloader".
The second step is to stop all communication from the client to the server, so the server will never see any WDL packets and the client will never respond to any WDL packets sent to it.