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Local PDF tool - browser processing

Stamp a confidential PDF without uploading

Stamping a confidential PDF without uploading means placing visible status marks — Confidential, Draft, Approved, Void — onto sensitive pages locally. You choose the stamp, place it on the right page, and export, so a document marked Confidential never tours a stranger’s server to get that mark.

Stamp locally See the proof

0 bytes sent proof

What the widget measures

The panel counts what leaves your browser after you choose a file. The site's own scripts and fonts load like any web page — what you will never see is a request carrying your PDF. Check it here, or open your browser's Network tab and see for yourself.

0 bytes of your document sentStarts measuring when you choose a file on a tool page
Document request bodies
0 bytes
App network after file open
0 bytes
Processing engine
Browser WASM worker

The number is scoped to request bodies after you choose a document. App assets such as JavaScript, WASM, and fonts can still load; those are not your PDF bytes.

Verify it yourself
  1. Open DevTools, then the Network tab.
  2. Choose a PDF in the tool and complete the action.
  3. Filter for fetch or XHR requests; document processing should not create a request carrying your file.

Stronger check: load the tool page first, then disconnect from the network before choosing the file. Already-loaded tool code can continue processing locally, but a first visit still needs the site assets.

Local vs. online

How local processing compares

Doing this in Lemmafour keeps the file on your device. A typical online PDF tool uploads it to a server first — here is the practical difference:

  Typical online PDF tool Lemmafour
Where your file goes Uploaded to the provider’s servers Stays in your browser — never uploaded
Works offline No — it needs a round trip to their server Yes, once the page has loaded
Account or sign-up Often required Never — no account, no email
What they keep afterwards Your file sits on their servers until they delete it Nothing to keep — it never left your device

Steps

How to do it in Lemmafour

  1. Choose Stamp locally.
  2. Open the confidential PDF.
  3. Pick Stamp in the toolbar.
  4. Choose the stamp style and place it on the right page.
  5. Apply and export the stamped PDF.

Expert note

Stamps are visible labels

A stamp can communicate status, but it does not enforce access control, encryption, or redaction. If a document contains sensitive information that should not be shared, redact or remove that content before stamping. If the stamp is only for internal status, keep the original and stamped output named clearly to avoid sending the wrong version.

FAQ

Questions people ask before using this tool

Can I add a Confidential stamp?

Yes. The stamp tool includes confidential-style page markings.

Does stamping protect the PDF?

No. It adds visible content; it does not restrict opening, copying, or forwarding.

Can I stamp before signing?

Yes. You can stamp, sign, and export in the editor workflow.

Related private PDF workflows

Keep working locally

Redact a PDF without uploading Use secure redaction mode locally in your browser and verify that redacted text is not recoverable. Sign a PDF without uploading Add a drawn, typed, or imported visual signature to a PDF locally in your browser. Edit a PDF without uploading it Open the Lemmafour PDF editor and edit a PDF in your browser without sending document bytes to a server. Prepare a PDF for print without uploading Use Print Doctor locally to check page size, orientation, margins, and print risks before exporting. PDF tool hub Browse the shipped local PDF tools.