Is my PDF uploaded anywhere?

No. The PDF is read, drawn, marked and saved inside this browser tab: pdf.js draws the pages and pdf-lib writes the annotated copy, both running in the page. No byte of the file, its text or your notes is sent anywhere or passed to analytics. The only thing stored in your browser is the color, opacity and mode you last chose. The file and its annotations are not stored, so they are gone when the tab closes unless you save the PDF or the .json.

Does highlighting hide or redact the text underneath?

No. A highlight does not redact: it is a translucent colored box multiplied over the page, so the words under it stay visible and stay in the file as text, and they can still be selected, searched and copied in the saved PDF. After saving, the tool reopens the copy in the tab, looks up each highlight's words in its text and shows the result below the tool. Removing text from a PDF takes a redaction tool that deletes it from the file; this tool does not delete any text.

Can I edit or remove a highlight after saving the PDF?

Not as an annotation. Saving flattens highlights and rectangles into the page content, so other PDF readers show them but do not list them as annotations to select, edit or delete. Notes are the exception: each note is saved as a PDF note annotation, which readers can open and delete. To keep editing, save the optional .json with the PDF, then later open the original PDF here and load the .json: every mark comes back with its page, position, color, opacity and note.

Can I highlight a scanned PDF?

A scanned page is an image with no text layer, so there are no words to select. On such a page the tool switches to Rectangle: drag over the area, or type its left edge, top edge, width and height in points, and the rectangle is saved filled in your color with a solid outline. Searchable PDF OCR on this site adds a text layer to a scan, after which its words can be selected and highlighted here.

Can I highlight without a mouse, or on a phone?

Yes. Type a word or phrase into Find on this page and press Highlight matches to highlight each match on that page, up to 500 at once. On a touch screen, select the words, then press Highlight selection. Rectangles can be typed as four numbers instead of dragged, and every button, color choice and note field can be reached with the keyboard.

Does it work on rotated pages?

Yes. A page the PDF turns 90, 180 or 270 degrees is shown turned, and each mark is converted from the page as shown into the file's own coordinates with the same transform the page is drawn with, so it is saved over the words you selected. On a 612 by 792 point page turned 90 degrees, a box 100 to 300 points across and 50 to 70 down from the top left of the screen is saved at x 50 to 70 and y 100 to 300 in the file.

Is there a size limit?

PDFs up to 50 MB open. One page is drawn at a time, fitted to the width of the pane, with 150% and 200% zoom. A PDF that needs a password to open is refused, since the tool has no password prompt, and one encrypted with an owner password is refused because a copy with highlights could not keep its protection. A PDF with a digital signature opens, and the page says that the signature will not validate in the saved copy, since the copy is a rewritten file.

PDF Highlighter

Open a PDF and select words on the page to highlight them in yellow, green, pink or blue at 25, 40 or 60 percent opacity, or type a phrase into Find on this page to highlight each match, up to 500 at once. Pages with no text layer, such as scans, take rectangles you drag or type in points. Each mark can carry a note, Undo steps back through your last 100 changes, and the annotated PDF is saved with the highlights flattened into the page and the notes as PDF note annotations. An optional .json keeps each mark with its page, position, color and note, so you can load them onto the original PDF and keep editing. Pages turned 90, 180 or 270 degrees are marked where you see the words, and the file never leaves this tab.

PDFnone open

The page appears here, with its text ready to select.

annotationsnone yet

Highlights and rectangles appear here, in order, each with its note.

· or drop one anywhere on the stage

Never uploadedNo accountMarked in this tabUp to 50 MB

Pages

none yet

Annotations

none yet

Page shown

not drawn yet

Export

PDF, JSON

Selection on a page rotated 90°612 x 792 pt shown 792 x 612; box x 100 to 300, y 50 to 70 from the top left
saved at PDF x 50 to 70, y 100 to 300, over the same words
Saved, then reopenedthe annotated PDF, opened again in this tab
save the annotated PDF and it is reopened here and checked
Text under a highlightcopied or searched in the saved PDF
save a copy, and the words under a highlight are looked up in it

Accuracy. A highlight is a colored layer drawn over the page and flattened into the page when you save: the text beneath it is not redacted or removed and stays selectable, searchable and copyable, and other PDF readers show the highlight but cannot edit or delete it as an annotation. Notes are saved as PDF note annotations, and a page with no text layer, such as a scan, takes drawn rectangles instead of text selection. There is no text editing or reflow, and PDFs up to 50 MB are read and saved on your device, never uploaded.

Common questions

Is my PDF uploaded anywhere?: No. The PDF is read, drawn, marked and saved inside this browser tab: pdf.js draws the pages and pdf-lib writes the annotated copy, both running in the page. No byte of the file, its text or your notes is sent anywhere or passed to analytics. The only thing stored in your browser is the color, opacity and mode you last chose. The file and its annotations are not stored, so they are gone when the tab closes unless you save the PDF or the .json.
Does highlighting hide or redact the text underneath?: No. A highlight does not redact: it is a translucent colored box multiplied over the page, so the words under it stay visible and stay in the file as text, and they can still be selected, searched and copied in the saved PDF. After saving, the tool reopens the copy in the tab, looks up each highlight's words in its text and shows the result below the tool. Removing text from a PDF takes a redaction tool that deletes it from the file; this tool does not delete any text.
Can I edit or remove a highlight after saving the PDF?: Not as an annotation. Saving flattens highlights and rectangles into the page content, so other PDF readers show them but do not list them as annotations to select, edit or delete. Notes are the exception: each note is saved as a PDF note annotation, which readers can open and delete. To keep editing, save the optional .json with the PDF, then later open the original PDF here and load the .json: every mark comes back with its page, position, color, opacity and note.
Can I highlight a scanned PDF?: A scanned page is an image with no text layer, so there are no words to select. On such a page the tool switches to Rectangle: drag over the area, or type its left edge, top edge, width and height in points, and the rectangle is saved filled in your color with a solid outline. Searchable PDF OCR on this site adds a text layer to a scan, after which its words can be selected and highlighted here.
Can I highlight without a mouse, or on a phone?: Yes. Type a word or phrase into Find on this page and press Highlight matches to highlight each match on that page, up to 500 at once. On a touch screen, select the words, then press Highlight selection. Rectangles can be typed as four numbers instead of dragged, and every button, color choice and note field can be reached with the keyboard.
Does it work on rotated pages?: Yes. A page the PDF turns 90, 180 or 270 degrees is shown turned, and each mark is converted from the page as shown into the file's own coordinates with the same transform the page is drawn with, so it is saved over the words you selected. On a 612 by 792 point page turned 90 degrees, a box 100 to 300 points across and 50 to 70 down from the top left of the screen is saved at x 50 to 70 and y 100 to 300 in the file.
Is there a size limit?: PDFs up to 50 MB open. One page is drawn at a time, fitted to the width of the pane, with 150% and 200% zoom. A PDF that needs a password to open is refused, since the tool has no password prompt, and one encrypted with an owner password is refused because a copy with highlights could not keep its protection. A PDF with a digital signature opens, and the page says that the signature will not validate in the saved copy, since the copy is a rewritten file.

A highlight is a colored layer drawn over the page and flattened into the page when you save: the text beneath it is not redacted or removed and stays selectable, searchable and copyable, and other PDF readers show the highlight but cannot edit or delete it as an annotation. Notes are saved as PDF note annotations, and a page with no text layer, such as a scan, takes drawn rectangles instead of text selection. There is no text editing or reflow, and PDFs up to 50 MB are read and saved on your device, never uploaded.