About
A thread you can follow.
Filum is 46 PDF and image tools — every one running entirely on-device, in your browser — built one at a time and verified on real documents before they appear. No account. No upload. No claims that haven't been measured.
The name is the principle
Filum is Latin for thread. For centuries, important documents were bound and sealed with thread — “red tape” is literally named for it. The thread was a promise: this document is intact, and nobody has touched it. That is the standard every tool is held to: the output is exactly what you chose, and nothing else is altered.
On-device — every tool, no exceptions
Organize, merge, split, sign, rotate, redact, watermark, compress, and convert — every tool runs entirely in your browser. Your file never reaches a server, because there is no server in the path: nothing is uploaded, nothing is stored, nothing has to be trusted. No permanent storage, no profile, no account.
One verified tool at a time
A tool is listed only after it passes verification against real documents — real PDFs in a real browser, output bytes inspected, every failure path tested. There is no “basic support” and no hedged claim. If a tool can’t meet that bar in full, it isn’t listed.