How SwiftSave keeps files on your side of the glass.

Your browser downloads the app code like any website. When you drop a file, that code reads the file from disk, transforms it in memory, and offers a download link. That path does not require you to send the file to SwiftSave’s servers for routine conversion. Treat it like editing an image in a desktop app: the app sees the file because you chose it, not because it was silently uploaded.

Network activity you will still see is normal site traffic: HTML, JavaScript, fonts, and WebAssembly bundles (for example FFmpeg-based video helpers). Those payloads are the program, not your private document contents.

The main converter routes images through decoders and encoders available in the browser, uses the Web Audio API for many audio paths, and relies on WebAssembly FFmpeg for heavier video re-encodes when the format needs it. Document and spreadsheet routes use parsing libraries such as SheetJS for XLSX/CSV/JSON style workflows.

Very large files can still feel slow because your laptop or phone is doing the work. That is the tradeoff for not handing the same file to a stranger’s GPU farm.

The metadata viewer reads structure your browser can already access. It is useful for checking dimensions, container tags, and basic properties before you share a file. It is not a forensic suite and it does not upload the file for “deep analysis” on a backend.

Browsers change, codecs evolve, and some corporate devices lock down WebAssembly or storage. If a conversion fails, try a smaller clip, a different browser, or a desktop tool for edge cases. When in doubt, keep a backup of the original file before converting.

For who operates SwiftSave and author bios, see the About page. For policies, read the Privacy Policy.