About the document reader
Highlighting a PDF should not require buying desktop software or handing your document to a server you know nothing about. This online document reader opens PDF, DOCX, EPUB, Markdown and plain text files directly in your browser and lets you highlight text with four colours. There is no sign-up, no watermark and no limit on how much you annotate.
The important part is what does not happen. Your file is parsed by your own browser — it is never uploaded, never written to disk on a server, and never given a public URL that somebody else could find. That matters if you are annotating a contract, an unpublished manuscript, medical notes, or a paper you have not been given permission to share. Close the tab and the file is gone from the page; your highlights stay in your browser's own storage so the document is still marked up when you come back.
PDFs render exactly as they were laid out, so page numbers, figures and columns stay where the author put them. Highlights on a PDF are anchored to the position on the page, the way a real highlighter pen would sit. For DOCX, EPUB and text files, which reflow to fit your screen, highlights are anchored to the words themselves so they survive a change of window size or font size. Both behave the way you would expect them to.
If you would rather work with the text than the page, the Read and Edit tab lifts the extracted text into a full editor with formatting, lists, tables and the focus reading mode, so you can rewrite a passage or pull out the parts you need. And if you want your highlights to follow you across devices, or you want to turn the document into flashcards, a quiz, a mind map or an audio recap, a free account carries the whole document across.
Frequently asked questions
Is this PDF highlighter free?
Yes. Reading and highlighting are free with no account, no trial and no watermark.
Do I need to sign up?
No. You can open a document and highlight it without an account. Signing up is only needed to save highlights across devices.
Is my document uploaded to a server?
No. The file is opened and parsed in your browser. It never leaves your device and never gets a public URL.
What file types can I open?
PDF, DOCX, EPUB, Markdown and plain text. You can also paste text straight into the reader.
Can I read a DOCX without Word?
Yes. DOCX files are rendered in the browser, so you do not need Word or an Office subscription.
Will my highlights still be there next time?
Yes, on the same browser and device. Highlights are kept in your browser's storage, so clearing browser data removes them.
Can I download the highlighted PDF?
Not yet. Highlights are shown in the reader. Saving a marked-up copy is something an account will handle.
Is there a file size limit?
Very large files are limited by your device's memory rather than by us, since all the work happens in your browser.
