Observed arrival · 2026-10-18

A PDF signature hidden in the file

firmadigitalpdf.com Visit website

Editorial interest 72/100 Selection signal · not a rating of the site

FirmaDigitalPDF presents a browser-based tool for adding a hidden label to a PDF and later checking the file.

Landing page captured for the 2026-10-18 issue.

For: People sharing PDFs who need source or change checks
Worth noticing: The signing flow accepts labels of 1–60 characters and shows SHA-1, SHA-256, and SHA-512 fingerprints for the resulting file.

Field notes

The page presents separate signing and verification flows. For signing, users select a PDF (up to 80 MB), review metadata slated for removal, and enter a hidden label of 1–60 characters; the page says processing stays in the browser. The resulting download is described as carrying a date in its filename and displaying SHA-1, SHA-256, and SHA-512 fingerprints. Verification is presented as re-uploading that file to extract the label and check integrity.

Observed signals

Read the marks

Editorial observations of this landing page, not a rating.

○OpenPublic substance visible

◎NicheUnusually specific use

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