To prevent paid sync services, you should license your protocols and data formats in AGPL, which requires derivative work (third-party sync services) to be open sourced.
The client app in contrast, should be fine even in permissive licenses.
To prevent paid sync services, you should license your protocols and data formats in AGPL, which requires derivative work (third-party sync services) to be open sourced.
The client app in contrast, should be fine even in permissive licenses.