How Private Browser Image Processing Works
Understand local image decoding, canvas processing, downloads, network requests and what to verify before trusting a browser image tool.
Local does not mean the website is offline
The HTML, JavaScript, fonts, analytics or advertising resources may arrive over the network. Local processing is a narrower claim: selected image bytes are not intentionally sent to an image-processing server. A dedicated codec may also be downloaded before it works locally.
| Stage | Typical location | What to verify |
|---|---|---|
| Select file | Operating-system picker | Only chosen files are exposed |
| Decode | Browser memory or local codec | No image request appears |
| Transform | Canvas or worker | CPU use stays on device |
| Download | Local blob/object URL | Expected type and filename |
Verify with browser tools
- Open the browser’s developer tools and Network panel.
- Clear existing requests.
- Select a non-sensitive test image.
- Process and download it.
- Look for POST, PUT or unusually large requests during those actions.
- Inspect the destination and payload metadata of anything unexpected.
The site’s Local Processing page provides a product-specific architecture and capability check.
Limits of the privacy claim
Local processing does not protect a compromised device, malicious browser extension or altered website code. It also does not automatically remove metadata from an output. Use an updated browser, verify the domain and HTTPS connection, keep sensitive originals private and inspect downloaded files before sharing.
Common mistakes
- Equating “runs in a browser” with “never uses a network.”
- Testing with a sensitive image instead of a disposable sample.
- Ignoring analytics, advertising and codec requests because they are not image uploads.
- Assuming canvas export preserves or removes all metadata.
- Trusting a privacy slogan without a verifiable explanation.
Frequently asked questions
Can a website read every photo on my device?
A normal file input exposes only files you deliberately select, subject to browser and operating-system controls.
Does local conversion remove EXIF?
Often canvas re-encoding does not copy source EXIF, but do not treat that as a guarantee; verify the output.