No uploadYour file stays on this device.
Your original stays as it isYou download a new copy. Your file is never changed.
Free, no sign-upNo account and no daily limit.

What happens to your file

Everything below happens inside your browser, on your own device. The PDF and the pictures you add are never uploaded.

Your browser opens the PDF and draws the pages with pdf.js, the PDF viewer built into Firefox.
Text you add is written into the page as real text in the Sarabun font, which covers Thai, English and Vietnamese. Only the letters you use are embedded, so the file stays small, and the text can be selected, searched and copied.
Drawings, lines, arrows, boxes and circles are saved as vector lines, so they stay sharp when someone zooms in.
Pictures are re-saved in your browser before they go into the file. This also removes hidden photo data such as GPS location.
Highlights are see-through color, mixed so the text underneath stays dark and readable.
Everything you add becomes part of the page, not a separate comment layer. The rest of the file, including its text, links, bookmarks and form fields, is left as it was.

In short

Choose a PDF
Pick a tool
Tap or drag on the page
Press “Save PDF” and download

How to edit a PDF

Choose a PDF. The first page opens large, with small previews of every page below it.
Pick a tool: Text, Draw, Highlight, Shapes, Image or White-out.
For text, tap where it should start and type in the box. For the other tools, drag on the page.
Tap anything you added to move it, change its color or size, or delete it. Undo and redo work for every step.
Press “Save PDF” and download the file. “Back to editing” keeps everything in place if you want to change something.

When people use it

Fill in a form that has no fields

Type your name, address and answers on top of the lines of a printed-style form.

Mark up a document

Highlight the important lines, circle a number and add an arrow with a short note for whoever reads it next.

Fix a small mistake

Cover a wrong date or price with White-out and type the right one on top.

Add a logo or a stamp

Put a company logo, a photo or a scanned stamp on the page.

What it can’t do

It can’t change text that is already in the PDF. White-out only covers it, and the old text can still be copied from the file. To remove information for good, use Redact PDF.
The text font covers Latin, Thai and Vietnamese letters. Text in other scripts, such as Chinese or Arabic, is saved as a picture, so it can’t be copied or searched.
Text is added line by line. Long text does not wrap by itself, so press Enter where a new line should start.
Password-protected PDFs, and PDFs whose owner has blocked editing, can’t be opened.
Any digital signature already in the PDF stops being valid once the file is changed.

Questions about editing PDFs

Is my PDF uploaded?

No. pdfMB edits the file inside your browser, and it never leaves your device. You can check this in your browser’s network tools.

Can I change the existing text in my PDF?

Not directly. PDF files usually contain only the letters that were used, so typing new words into old text often gives missing or wrong letters. Cover the old text with White-out and type the new text on top instead.

Will Thai text look right and copy correctly?

Yes. Tone marks and vowels sit in the right place, and when you copy the text from the saved PDF you get the same letters you typed, including words like “น้ำ”.

Can people remove what I added?

It is written into the page, not added as a comment that can be clicked away. Someone with a PDF editor can still change any part of a page, so this is not protection against changes.

Can I undo a mistake?

Yes. Undo and redo cover every step: adding, moving, resizing, recoloring and deleting. On a computer you can also press Ctrl+Z and Ctrl+Shift+Z.

Is there a page or size limit?

There is no fixed limit. Very large files can run out of memory on some phones.

Edit PDF