Why won't my PDF Let me highlight?

Most likely because the file is composed of images (possibly scans) and does not contain any “real” text. If you can't select the text with the text selection tool then you can't highlight it, either. Use other markup tools, like the Square tool, instead.

How do you unlock a PDF file?

Click CHOOSE FILE. It's a green button on the right side of the page. Select your PDF file. Click Open. Enter the user password. Click UNLOCK. Click VIEW & DOWNLOAD IN BROWSER.

How do I unlock a PDF for editing?

Click CHOOSE FILE. It's a green button on the right side of the page. Select your PDF file. Click Open. Enter the user password. Click UNLOCK. Click VIEW & DOWNLOAD IN BROWSER.

Protected Highlight in PDF For Free

Drop document here to upload

Select from device

Up to 100 MB for PDF and up to 25 MB for DOC, DOCX, RTF, PPT, PPTX, JPEG, PNG, JFIF, XLS, XLSX or TXT

Last updated on Sep 14, 2026

Try most popular PDF tools

Discover a full set of tools to handle any document task.

Edit PDFs

Make quick PDF edits online.

Sign

Add legally binding signatures.

Merge

Combine multiple PDFs.

Request signatures

Send a document for signing.

Convert

Transform PDFs into other formats.

Find form online

Browse the online forms library.

Rearrange

Change the order of pages.

Send PDFs for review or editing.

Compress

Reduce PDF file sizes.

pdfFiller ranks among the best

pdfFiller is rated 4.6 out of 5 stars across 1,000+ G2 reviews.

Read all reviews

Takes a little time to learn, but works very well

Anonymous Customer

Site can be difficult to navigate when searching for a doc not already created.

Jaclyn P

very good, it is a little hard to navigate. The user interface could be cleare

Jay b

it is very easy to use and very informative. i would recommend it to everyone.

fatou k

Effectively resourceful as an administrative supervisory tool.

Belinda G

So far so good So far so good. Easy to use anywhere since it is web based and I don't have to worry about which computer I'm using, whether at home, office, or other.

Geoffrey Katz