Security architecture
Your deal documents never leave your machine.
Five independent layers, each one verifiable. Built for Magic Circle firms, bulge-bracket banks and PE sponsors whose IT teams say no by default.
Five security layers
100% in-memory processing
- Files are read into your browser’s sandboxed memory and compressed by background workers on your own device.
- No file chunks, byte streams or previews are ever transmitted.
- PDF repacking, lossless image re-encoding and Office re-zipping all run on your own CPU and RAM.
No storage, no cache, no database
- Compression runs in your browser, so your documents never reach us: no buckets, no database, no copies.
- Results are created inside your browser and stay there until you save them. We never see them.
- No cookies, browser storage or caches ever hold document content.
Works with Wi-Fi off
- The compression engine runs under a strict content security policy that blocks every network request it could make.
- Once the engine is ready, compression keeps running in airplane mode: the strongest proof there is.
- No third-party scripts, trackers or analytics anywhere on the site.
Proof, file by file
- Every PDF is checked by two independent PDF engines: each page rendered and compared pixel by pixel with the original, plus every word of text and the full document structure.
- Word, Excel and PowerPoint files are compared part by part with SHA-256 fingerprints, PNG and JPEG images pixel by pixel.
- If anything differs, you get your original back. The file you download is byte for byte the one that passed.
- Tested on 268 real-world documents and images and 134 deliberately tricky edge cases: not a single difference.
Compliant by omission
- Documents are compressed where they already are, on your machine, so they never enter our custody: no deal content for us to process, store or hand over.
- Your files never leave your machine, so document content is never transferred: not to us, not across a border.
- Your IT team can verify each layer themselves, starting with the air-gap test below.
Air-gap test
Open PreVDR and wait until it says Ready. Then turn off your network connection and drop a deal document. It compresses anyway, because nothing is ever sent. Open your browser’s network tab: not a single request carries your file.
For your compliance team
No sub-processors
Files are compressed in your own browser, so no third party ever handles document content.
Information barriers
Files stay on your machine and are shared with no one, so clean-team and ethical-wall rules stay intact.
No install
Runs on locked-down laptops, in the browser they already have. No install, no admin rights, no IT ticket.
Open, pinned components
Built on qpdf, libjpeg-turbo, oxipng and pdfium. Versions pinned, and every engine file is checked against its published checksum.
NDA friendly
Documents stay on your machine, so they are never disclosed to a new party, not even to us.
Signatures stay valid
Signed and password-protected PDFs are left exactly as they are. Signed Office files keep every part byte for byte.