Nevquo Pixel › Prove it stays on your device
Prove it stays on your device
Most online compressors upload your files and ask you to take their word that they are deleted. Nevquo Pixel works inside your browser instead, and you can watch it happen. These checks take about two minutes and need no technical skill.
One page works differently, on purpose. The website image analyzer sends the page address you type to a small Nevquo service so it can list that page's images. It never receives your own images, and it is not part of the optimizing pages this check is about.
Three steps to see it for yourself
- Open the Network tab and clear it
Your browser keeps a log of every request a page makes, and no website can edit that log. Open Nevquo Pixel, then press F12 (Windows and Linux) or Cmd + Option + I (Mac). In Safari, first switch on the Develop menu under Settings, then Advanced. Click the Network tab, then the clear button (a circle with a line through it) so the list starts empty.
- Add your images and read the list
Drop in a few photos. Rows will appear, and this is what to look for:
- Every row is a
GET. That is a file coming to your browser: the page's own scripts and image tools. - Type
method:POSTin the filter box (Chrome, Edge and Firefox support this). The list stays empty, because nothing is sent out. - Type the name of one of your own photos into the filter box. No row matches, because your file names are never sent anywhere.
- Every row is a
- Turn off the internet and use it again
Switch on airplane mode (or unplug the cable, or choose Offline in the Network tab's throttling menu), then reload the page and add an image. It still opens and still works, because the optimizing happens on your device and the app saved its own files during your first visit. On a phone, "Add to Home Screen" installs it like an app.
In our own test, after one online visit and with the network switched off, the page reloaded and optimized 3 of 3 test images (a JPEG, a PNG and a WebP). A HEIC photo and a TIFF that had never been opened before also worked offline. If you depend on a rarely used format such as JPEG XL while offline, open one once while you are online first.
What you will see in the list
Adding an image makes your browser fetch the tools it needs, once. These are downloads from our own address, not uploads.
| What you see | What it is | Carries your image? |
|---|---|---|
/ or the page name | The page itself | No |
main-….js, worker-….js, .css | The app and its background worker | No |
….wasm (for example mozjpeg_enc, webp_enc, avif_enc) | The image tools, saved as compact programs. A format is fetched the first time you use it. | No |
….woff2 | The page font | No |
blob: addresses | Results held in your browser memory so you can preview and download them | Yes, but they exist only on your device |
After your first visit some rows say (ServiceWorker) or disk cache. They are the app's own files saved by your browser, not new downloads.
We ran this check ourselves
On 10 October 2026 we opened the built site (version 1.3.0) in Chromium 141.0.7390.37, added 13 test images of different formats and logged every request the page made while it worked. 13 of 13 images were optimized. The log held 26 requests: all were GET, all to the site itself, with 0 bytes sent in request bodies and 0 WebSocket connections. 4 of the requests were image-tool (.wasm) downloads.
The test script, scripts/verify-no-upload.mjs, ships with the source. Your browser is the better witness, which is why the steps above come first.
Go one step further: the rule book your browser enforces
In the Network tab, click the first row (the page itself), then Headers, then look for content-security-policy in the response headers. It contains connect-src 'self' blob: data:. That is an instruction from the site to your browser: this page may not connect to any other web address. It also contains form-action 'none', so no form can be sent anywhere. And the site is a set of static files with no upload handler on the server, so there is nothing for an upload to reach.
What these checks do not show
- They check today's page. A site could change tomorrow, which is why the check is quick and you can repeat it whenever you like.
- Our host sees what any website host sees. Ordinary server logs record your address, the time and the page requested, as described in the privacy statement. They never include your images, because your images are never sent.
- Your own browser extensions can read pages you open. If that worries you, use a private window with extensions switched off.
Frequently asked questions
Why do I see so many requests when I add one image?
The first time you use a format, your browser downloads the matching image tool (a .wasm file, sometimes a megabyte or two). Those are downloads from this site to you. After that they come from your browser's saved copy.
Does the settings sync link upload my images?
No. A sync link only contains your settings, and it is a plain address you copy yourself. It never contains an image.
What does the service worker store?
Only the app's own files, so the page can open offline. It does not store your images.
Can I run the check on my phone?
The airplane-mode step works on any device. The Network tab is easiest on a computer, so do that step there.
What if I ever see a POST, or a request to another site?
Please tell us straight away, with a screenshot of the row. That would be a bug, and we want to know.