How it works

BlindWMLocal is a static website: HTML, CSS, and JavaScript served from this domain. There is no backend service that receives or processes your images. Embed, extract, and detect all run inside your web browser using the bundled blind-watermark library.

  1. You open a tool page. Static assets load from this site (first visit needs network).
  2. You choose an image from your device. It stays in browser memory — never POSTed to us.
  3. Add: enter text, set strength, embed via blind-watermark in the browser.
  4. The library returns PNG data; we convert to JPEG/PNG/WebP locally if you choose.
  5. Extract: supply length/level (or auto-detect 3–64) to decode the string.
  6. Detect: optional decode probe plus frequency stats — screening only, not legal proof.

Verify offline mode (recommended)

The strongest proof that images are not uploaded: work while disconnected.

  1. Open Add watermark, Extract, or Detect and wait until the page is fully loaded (first run may fetch the watermark library).
  2. Disconnect Wi‑Fi, unplug Ethernet, or enable airplane mode.
  3. Before choosing a file, confirm the browser reports offline (optional: DevTools → Network → Offline).
  4. Choose an image and complete embed, extract, or detect — it should still work.
  5. Download or copy results as usual. No network is needed for processing.

First visit to BlindWMLocal still requires network to download pages and scripts. After that, your browser may cache assets; reload while offline only works if those files are already cached.

Verify in DevTools (Chrome / Edge / Firefox)

  1. Open a tool page with Developer Tools → Network → Preserve log.
  2. Embed or extract an image (online or offline after load).
  3. You should see .js / .css loads when the page opened — not multi‑megabyte POST bodies of your photos during processing.

We have no API that accepts image uploads. Same privacy model as ShrinkLocal compress — pure browser, no backend.