Check that your files stay local
You can check file processing yourself. Use a harmless test file and a desktop browser such as Chrome or Edge. This checks the operation you observe; repeat it for each tool you want to verify.
- Open the tool and its browser developer tools (F12 or Ctrl+Shift+I; on macOS, Cmd+Option+I). Select Network, enable Preserve log, and select All to include every request type.
- Keep recording enabled. Clear the log, reload the page, and wait for it to load. Normal requests download the page, scripts and styles.
- Select a test file, run the tool, and download the result. Some tools load additional scripts or the PDF worker on first use. A GET request for code is not a file upload.
- Inspect new HTTP requests: look at their URL, method, Payload and Initiator. File bytes must not appear in a request body, form data or URL. Inspect unexpected requests regardless of their method or domain. Also check WebSocket messages if any appear.
- A blob: or data: URL represents browser-local data. It may appear in previews or downloads and does not itself send your file to a server.
Optional offline check
After the tool has processed a test file once and finished loading its code, choose Offline in the Network panel. Process the test file again without reloading or navigating. A successful result supports local processing for that operation. A failure may mean code was not loaded yet; it does not by itself prove an upload. This is not a promise that every page is available offline.
What this does and does not show
The website still connects to its hosting service to load pages and assets. ShrinkBeam currently counts ordinary page requests on the server; it does not report tool actions or download clicks from your browser. Your selected files and file names are not part of those analytics records. Extensions and other software can create separate traffic. Do not share network logs containing sensitive information.
Measured results
Result sizes come from the actual file bytes. Rounded sizes and percentages are calculated from those bytes. A quality setting is an encoder setting, not a measured percentage of visual quality. Check the downloaded file for readability and completeness.