For many developers, privacy is not marketing fluff. It is a real workflow requirement when they are handling request bodies, logs, or config with sensitive fields.
A browser-side tool reduces the need to send payloads to a remote application server just to prettify, validate, or compare text. That does not eliminate every risk, but it cuts out one unnecessary exposure point.
Clear privacy copy, obvious local-only messaging, working tools above the fold, and legal pages that explain what the tool does and does not process.