Core only:
https://seafile.servator.de/sbc/LONGAN/Longduino/cores/longduino-core-0.2.2.zip
Package Index (Core and dfu-util/openocd/toolchain for Linux x64/arm64/armhf and Windows):
https://seafile.servator.de/sbc/LONGAN/Longduino/package_longduino_multi_index.json