Is there a file size limit?

A single file may be up to 100 MB, and a batch up to 50 files. Those are guardrails rather than a paid tier — the work happens on your machine, so an enormous document is limited by your own memory before it is limited by us.

Where does the processing actually happen?

In this tab. The file is read locally, converted or edited locally, and handed back as a download — no copy is sent to a server, so there is nothing for anyone to breach or keep.

Will it work on a phone?

Yes. The layout adapts to a small screen and the processing runs in the mobile browser, so a photo or a downloaded document can be handled on the device it arrived on.

Is this free, or free until it asks for a card?

Free, with no upsell behind it: no account to create and no file-count quota that appears halfway through a job.

Underline PDF Text

Underline passages in the editor.

Drag & drop the PDF you want to edit

One document at a time — edits are flattened into the pages on save

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About Underline PDF Text

Underline PDF Text is here for changing what is on the page: underline passages in the editor. It takes PDF and produces PDF. Files up to 100 MB each, 50 at a time, and the work happens on your own machine rather than on a server.

The slow route to changing what is on the page is installing something, making an account and uploading the file; this is the fast route.

How to use Underline PDF Text in 3 steps

Drop the file on the page — PDF, one file up to 100 MB.
Set the text selection to underline, in the colour you pick.
Press Apply edits and download the PDF result.

What you get with Underline PDF Text

One job, done in the browser: underline passages in the editor.
Free to use, with no signup and no account
No watermark or logo added to your output
Works on desktop and mobile, no install

Underline PDF Text: questions

Is there a file size limit?: A single file may be up to 100 MB, and a batch up to 50 files. Those are guardrails rather than a paid tier — the work happens on your machine, so an enormous document is limited by your own memory before it is limited by us.
Where does the processing actually happen?: In this tab. The file is read locally, converted or edited locally, and handed back as a download — no copy is sent to a server, so there is nothing for anyone to breach or keep.
Will it work on a phone?: Yes. The layout adapts to a small screen and the processing runs in the mobile browser, so a photo or a downloaded document can be handled on the device it arrived on.
Is this free, or free until it asks for a card?: Free, with no upsell behind it: no account to create and no file-count quota that appears halfway through a job.