Show HN: TechRex – client-side PDF editor (no upload, no watermark)

1 pointsby Maaz-Sohail9 maanden geleden1 comments

Hi HN — I built a client-side PDF editor because I got tired of “free” tools that upload files and add watermarks. This runs entirely in the browser: edit text, add images/logos, sign, merge/split. No upload, no watermark, no signup.

How it works (tech): WebAssembly + Canvas + Web Workers. Text edits operate on glyph runs; when metrics don’t match exactly we do a subtle white-out behind the run and draw new text over it (preserves layout). Signatures use velocity-aware smoothing (Catmull–Rom → cubic Beziers). Export dedupes XObjects to avoid file bloat. Mobile Safari gets tiled rendering to keep memory stable.

Perf (measured): ~1.2s FCP / ~1.5s LCP on mid-range Android for the landing UI; TBT ~0–30ms during typical edits.

Privacy: default is offline—no network calls during edit/export. Any optional cloud action is explicit and TLS-only. No watermark, no usage caps.

Gaps: no full OCR yet; no global find/replace; batch stamping per-page for now.

Try it: https://pdffreeeditor.com/

Direct editor: https://pdffreeeditor.com/editor/

Script-light mode (disables analytics): https://pdffreeeditor.com/?lite=1

I’d love feedback on weird fonts, RTL, giant scans, or perf gotchas. Happy to share more internals and ship fixes live in the thread. — Maaz

1 comments

MrCoffee79 maanden geleden

I don't understand how your editor is supposed to work and it does not have online help? For example, how can I place my cursor at a particular place in the document and begin editing the text around my cursor location?