Here you can decompile schematics copied from Mindustry into Schemacode, a schema definition language, which can then be modified and compiled back into a schema again. Press the Export button on a Mindustry schematic, choose Copy to clipboard and paste the text into the left pane. Then press Decompile. You can compile the Schematic definition back to Mindustry schematics on the Schematics Builder page.
If your schematic contains processor(s), the code is decompiled into mlog.