I’m building a “compress to exact KB/MB” tool — what would make it feel trustworthy/useful? (maker feedback)

Hey Digg — I’m the maker of a small browser-based tool that compresses images to a target size (e.g., 20KB / 200KB / 1MB). It runs locally in the browser (no uploads).

I’m not here to drop links — I’m here to learn from designers who deal with real submission/upload constraints.

Two UX questions:

1. In your workflow, what’s the most painful “size limit” scenario? (forms, job applications, portfolios, client portals, etc.) What usually goes wrong?

2. What controls would you expect to make this feel predictable and trustworthy?
   (quality slider, max width/height, “keep text sharp” mode, PNG→JPG toggle for transparency, batch mode, before/after preview, clear failure messaging, etc.)

If anyone wants to test it, ask and I’ll share a link in the comments.