Disclaimer

This is an unofficial document. While every attempt has been made to ensure its accuracy, it was produced without any cooperation from VATSIM or IVAO, and no agreements (including NDAs) were signed during its making. The protocol was reverse-engineered by inspecting incoming/outgoing packets during the course of a regular network connection. No security measures were broken; the protocol is in plaintext, and the details of authentication measures are not documented (nor were the measures themselves reverse engineered).

This document is not an official approval to develop software for either network. To do so, you must get in touch with either network, and will likely have to sign an NDA and/or legal agreement to do so. Use this at your own risk!

By using any software derived from this documentation, you accept responsibility in the event any action - legal or otherwise - is taken against you by IVAO and/or VATSIM.

License

The original FSD protocol is in public domain, and its source code can be found here. However, the modified versions used by VATSIM and IVAO (which are the main focus in this document) are under NDA, and are therefore closed-source. Please refer to the respective networks' policies (IVAO, VATSIM) regarding restrictions on the use of their FSD implementations.

This document is licensed under the GPL, version 3.

Please see "License" under the "Preface" section for the full text.