ToolBoxUnderline PDF
Draw a line under important text in a PDF.
Free · No signup · Files stay on your device
or drop a file here
How to use Underline PDF
- 1Select your PDF file.
- 2Drag over the text you want to underline.
- 3Press the button to apply your marks.
- 4Download your PDF.
Your files stay private
Your file is processed on your own device. It is never uploaded to our servers.
Frequently asked questions
Is Underline PDF free?
Yes. ToolBox is 100% free. No signup, no watermark, no daily limit.
Are my files uploaded to a server?
No. All work happens inside your browser on your own device. Your files never leave your phone or computer.
Does it work on mobile?
Yes, on Android, iPhone, tablets and desktop. Very large files can be slow on older phones.