Mod to enable item transport between world, let mods execute HTTP requests, allows you to get UNIX time for your combinator circuits, monitor production statistics in your web browser etc.
Its complicated. It does not work in singleplayer. It does require an external program to run on the server.
Download this if you are going to play on a server that has this version of the mod installed.
TL;DR: DOES NOT WORK IN SP. Works only on clusterio enabled servers.
Server owners: To set up a clusterio server, have a look at https://github.com/clusterio/factorioClusterio/tree/1.2.x#readme and follow the instructions.
For support, I am Danielv123#4902 on discord and Danielv123 / _ on espernet #factorio.