What happens to a file from selection to download, which work stays on the device, and where the limits of browser processing apply.
Data-flow map
The path is short: selection → file-signature check → browser memory → decoding → bounded processing → output check → download. Exact Size Tools does not send the selected file to an application server during these operations.
Images: browser decoder and canvas, followed by a downloadable file whose format and dimensions are checked
PDFs: a local library loaded from this site, followed by a new PDF whose header and page count are checked
Temporary previews: object URLs revoked when replaced or cleared
Logs and optional analytics: selected file details are never included; Google services load only after visitor consent
Safety limits
Byte, pixel, file-count, and page-count limits reduce the chance that a damaged or unusually large file will exhaust browser memory. The tool checks the file signature before decoding it and stops on unsupported, corrupt, encrypted, or infeasible input. These controls reduce avoidable risk, but they are not a substitute for keeping an untouched original or using a trusted device.
A signature is a format identifier, not an antivirus scan. Decoding still uses device memory.
Image output
Actual encoded type, decoded output dimensions, and the selected byte rule
A technical pass cannot assess identity, document validity, or receiving-portal acceptance.
PDF output
PDF header, reload through the local library, and page count
Interactive features and signature validity need separate review.
Metadata-only DPI
Density tags in JPEG or PNG
Other metadata remains, potentially including location information.
The page and its libraries are downloaded from the host. The selected-file processing code does not send the selected file to a server. Optional advertising and analytics are separate third-party scripts; essential-only mode keeps them unloaded. Downloads saved by you remain on your device until you remove them.
To inspect the behavior, open your browser Network panel, choose essential-only, clear the request list, and process a non-sensitive test image. Code downloads are expected; no file-upload request is used by the processing workflow.