Attorney–client privilege and third-party tools
Privilege can be waived by disclosing privileged material to an outside party — and courts have increasingly scrutinized whether uploading documents to cloud services counts as that kind of disclosure, especially when the service's terms reserve broad rights to the uploaded content.
Converting briefs, contracts, and discovery documents locally in the browser avoids the question by not involving a third-party server at all. It also means the tool keeps working during depositions or court proceedings where WiFi is restricted or unavailable, since nothing about the conversion depends on a live connection after the page has loaded once.