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Local PDF tool - browser processing

Add text to a PDF without uploading

Adding text to a PDF places new, readable text on the page without changing the original content underneath — and Lemmafour does it locally. You click where the text should go, set the font and size, and export, while the source file stays on your device.

Add text 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 Add text locally.
  2. Use Choose PDF or LOAD PDF to open the file.
  3. Select Add Text in the toolbar.
  4. Click the page where the new text should appear.
  5. Set font size, color, and placement in the task controls, then Export.

Expert note

Added text is not the same as editing existing text

Adding text creates new PDF content on top of the page. It is useful for visible corrections, labels, and filled blanks, but it does not remove the original text underneath. If the old content is sensitive or wrong in a way that must not remain extractable, use secure redaction instead of covering it with new text.

FAQ

Questions people ask before using this tool

Can I add text to a scanned PDF?

Yes, as a visible overlay. The tool does not recognize or replace scanned text; it places new PDF text on the page.

Can I change the color and size?

Yes. The editor includes style controls for new text before export.

Does added text remain selectable?

The export writes PDF text where supported, so it can usually be selected by PDF readers.

Related private PDF workflows

Keep working locally

Edit PDF text without uploading Edit selectable PDF text locally in your browser. Your PDF stays on this device while Lemmafour applies text edits. Fill a medical PDF form privately Fill medical PDF forms locally in your browser without sending the document bytes to a server. Fill a PDF form without uploading Fill PDF form fields locally in your browser. Lemmafour keeps the PDF on your device. Sign a PDF without uploading Add a drawn, typed, or imported visual signature to a PDF locally in your browser. PDF tool hub Browse the shipped local PDF tools.