Yapaysız collects nothing, sends nothing and has no account.
Your documents, the analysis of them, your settings and your own rules. Documents are where you save them; settings and rules live in the app's own container on this Mac. None of it is transmitted anywhere: the app has no network access and no server to send anything to.
Only the documents you save, where you save them, and its own settings and rules file. Importing a Word or PDF file reads it; it is never changed. A suggestion changes your text only when you accept it.
Spelling uses your Mac's own dictionaries. Rewriting uses Apple Intelligence on this Mac. The first time it is needed, macOS itself may download the model files from Apple — that is the system doing it, not Yapaysız, and your text is not part of that request.
There is no telemetry, no crash reporting of our own, no identifier and no advertising. If macOS asks whether to share a crash report with developers, that is Apple's mechanism and your choice.