Lock a document down so it looks the same everywhere and nothing can be edited. Flattening bakes form fields, annotations, and layers into the page itself — ideal for a final version you're about to send. Nothing is kept afterward.
How to flatten pdf
Add your PDFChoose the PDF with forms, comments, or layers to lock.
FlattenRun it — everything is baked into the page image.
Check itThe result displays identically anywhere and can't be edited.
DownloadDownload the flattened PDF. It's gone from our side the instant you do.
What you can do
- Send a filled form that no one can alter
- Freeze comments and markup into a final copy
- Make sure a file looks identical on every viewer
- Stop form fields from being re-typed
- Prepare a print-ready final version
What happens to your file
Your files are never stored. Nothing is parked, queued, or kept — the moment your download is ready, it's gone, and no one ever sees it.
Plenty of online tools store your file on their servers and delete it later. PDF Cubby doesn't keep it at all — there's nothing left behind to clean up afterward.
Features
- Bakes in forms, annotations, and layers
- Consistent display across every PDF viewer
- Locks editing of fields and markup
- 5 free a day — unlimited with Pro ($4.99/mo, cancel anytime)
- Never stored — nothing kept afterward
Tips
- Flatten after you've finished filling and marking up — it's a one-way lock.
- Keep an editable copy for yourself before flattening the version you send.
- Adding a watermark? Apply it first, then flatten to bond it to the page.
Frequently asked questions
- Are my files kept after flattening?
- No. Your PDF is never stored — the instant your flattened file is ready, everything is gone and no one sees it.
- What does flattening actually do?
- It merges interactive and overlaid elements — form fields, annotations, layers — into the page itself, so they display identically everywhere and can't be edited.
- Will my filled-in form values stay visible?
- Yes. The values you entered are preserved as part of the page; they just can't be changed anymore.
- Can I undo a flatten?
- Not from the flattened file — keep an editable copy first if you'll need to change it later.
- Does it change how the document looks?
- No — it looks the same, it just can no longer be edited.
- Do I need an account?
- You get 5 free uses a day with no account. For unlimited use, sign in and upgrade to Pro — $4.99/month, cancel anytime. The 6 core tools (merge, split, extract, rotate, compress, convert) are always free and unlimited.
- Is my original modified?
- Never — you download a new flattened file and the source stays intact.