You can download the SHA-256 checksum for the 2.2.48 (latest) version of the Windows desktop app here:
https://sync.com/download/sync-packages/win/2.2.48/cur/sync-installer.exe.sha256
And the SHA-256 checksum for the 2.2.48 (latest) version of the Mac desktop app here:
https://sync.com/download/sync-packages/osx/2.2.48/cur/Sync.dmg.sha256
Note:
- Substitute sha256 with sha1 or md5 in the URLs, if you prefer an alternate checksum format.
- Substitute the version number (2.2.48) for different versions.