Is it safe to annotate a PDF online?

Yes — and ours is safer than most. Many free online tools quietly upload your files to their servers to do the work. We don't. Everything happens inside your browser on your own device, so your files never reach the internet. There's no upload step, no server copy, and no way for us (or anyone else) to see what you're working on.

Are my files uploaded to a server?

No. There's no server-side processing here. The whole tool is a tiny app that runs in your browser — we don't even have a server that could receive your files. You can confirm this by opening your browser's network tab while you use the tool: nothing leaves your device.

Do I need to sign up or pay?

No. There's no account, no email collection, no credit card. The tool is free to use as much as you want, on as many files as you want. We're supported by a few unobtrusive ads on the page — not by your data.

Can I edit my annotations later?

Saved annotations are flattened into the page content, so they can't be edited like Acrobat-style annotations. Re-annotate the original if you need a different result.

Will annotations show in other PDF viewers?

Yes — they're drawn into the page content, so any viewer renders them.

Annotate PDF

Add visual annotations to a PDF. Highlight text, underline, strikethrough, draw freehand, or drop comment markers. Six colours, undoable, baked into the saved PDF.

Features

Highlight, underline, strikethrough, freehand draw, note pin
Six colour choices
Per-page undo
Annotations are flattened into the saved PDF (visible in any viewer)
Works on any number of pages

How to annotate pdf

Drop the PDF — Drag the PDF you want to mark up.
Pick a tool — Highlight, underline, strikethrough, draw, or note.
Mark up — Click and drag on the page to add annotations. Use undo if needed.
Save — Click "Save with N annotations" — the marked-up PDF downloads.

Frequently asked questions

Is it safe to annotate a PDF online?: Yes — and ours is safer than most. Many free online tools quietly upload your files to their servers to do the work. We don't. Everything happens inside your browser on your own device, so your files never reach the internet. There's no upload step, no server copy, and no way for us (or anyone else) to see what you're working on.
Are my files uploaded to a server?: No. There's no server-side processing here. The whole tool is a tiny app that runs in your browser — we don't even have a server that could receive your files. You can confirm this by opening your browser's network tab while you use the tool: nothing leaves your device.
Do I need to sign up or pay?: No. There's no account, no email collection, no credit card. The tool is free to use as much as you want, on as many files as you want. We're supported by a few unobtrusive ads on the page — not by your data.
Can I edit my annotations later?: Saved annotations are flattened into the page content, so they can't be edited like Acrobat-style annotations. Re-annotate the original if you need a different result.
Will annotations show in other PDF viewers?: Yes — they're drawn into the page content, so any viewer renders them.