Smart or full flatten — form fields, annotations, and layers made permanent
WhiskFile Flatten PDF is a free online tool to smart or full flatten — form fields, annotations, and layers made permanent. Files are processed entirely in your browser — nothing is uploaded to any server.
Quick Answer
Smart or full flatten — form fields, annotations, and layers made permanent. WhiskFile's Flatten PDF is free, works in your browser, and requires no account. Your files never leave your device — all processing happens locally.
Upload your PDF
Select or drag and drop your PDF file. WhiskFile instantly analyzes it in your browser — detecting form field count and page count. Nothing is uploaded to any server.
Review the analysis
WhiskFile displays the form field count and page count. If form fields are detected, Smart mode is automatically recommended. If no fields are found, Full mode is suggested.
Choose flatten mode
Select Smart mode to flatten form fields only (instant, text stays selectable) or Full mode to rasterize every page as an image (flattens everything, tamper-proof).
Set DPI for Full mode
If using Full mode, adjust the DPI slider between 96 (screen quality) and 300 (print quality). The default of 200 DPI provides a good balance of sharpness and file size.
Flatten and download
Click 'Flatten & Download'. Smart mode completes instantly. Full mode shows a progress bar as each page is rendered. Download the flattened PDF when complete.
Verify the result
Open the flattened PDF to confirm form fields are no longer editable and annotations are permanently embedded. Keep a backup of the original if needed.
Max file size: 50 MB (free) · 500 MB (paid). Processing time: ~6s on average. Upload one file at a time.
Flatten PDF runs entirely in your browser — no software to install. Works on any device with a modern browser.
Windows & Mac
Chrome, Firefox, Edge, Safari
iPhone & Android
Safari, Chrome mobile
iPad & Tablets
Full touch support
Unlike server-based tools that upload your documents, WhiskFile processes everything locally in your browser. Your files never leave your device — not even temporarily.
No upload required
Files are processed in your browser — nothing is sent to any server
100% private
No server storage, no data collection, no third-party access
Works offline
Once loaded, works without an internet connection
“Password-protecting sensitive documents before sharing gives me peace of mind. Simple and reliable.”
Robert Liu
Compliance Officer
“Redacting confidential info from legal documents is critical. WhiskFile makes it foolproof.”
Nina Patel
Attorney
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Client-side processing
This tool now runs entirely in your browser — files never leave your device.
Result preview & sharing
Preview your processed file before downloading, and share results via a secure link.
No. Flattening is irreversible. Save a copy before flattening if you need to keep the editable version.
Smart mode flattens only form fields (text inputs, checkboxes, signatures) while keeping text selectable and file size small. Full mode renders every page as a high-res image — flattening forms, annotations, comments, stamps, and layers — but text is no longer selectable.
Flattening removes interactivity permanently by merging elements into the page. Locking (protect PDF) adds a password but keeps form fields intact.
Flattening ensures recipients see the PDF exactly as intended — filled values and signatures can't be altered, and the file is smaller and more compatible.
Smart mode flattens AcroForm fields only: text inputs, checkboxes, radio buttons, dropdowns, and signatures. Annotations, comments, and stamps are NOT affected. Text remains selectable and searchable, and the file size stays small.
Full mode renders every page as a high-resolution JPEG image, flattening everything: form fields, annotations, comments, stamps, signatures, layers, and transparency. Text is no longer selectable, but the result is tamper-proof.
Smart mode merges the visual appearance of signatures into the page, but cryptographic signature validation may be invalidated. Full mode rasterizes signatures as images. Always keep a backup of the signed original.
200 DPI (default) is ideal for most use cases — sharp text and images at a reasonable file size. Use 300 DPI for print-quality output. Use 96 DPI for screen-only documents where smaller file size matters more.
No. WhiskFile flattens PDFs entirely in your browser using pdf-lib and pdfjs-dist. Your file never leaves your device — nothing is uploaded. This makes it completely private.
No. WhiskFile has no file size limits, no page limits, and no daily task caps. Competitors like Sejda (50 MB, 50 pages, 3 tasks/hour) impose restrictions.
WhiskFile auto-detects form fields when you upload a PDF and displays the count (e.g. '12 form fields detected'). If fields are found, Smart mode is automatically recommended.
Not separately. Smart mode flattens form fields only. Full mode flattens everything including annotations. To flatten annotations alone, use Full mode — it rasterizes all page content.
Yes. WhiskFile flattens PDFs directly in your browser — no software to install. The flattened PDF is compatible with all standard PDF viewers including Adobe Reader, Preview, and Chrome.
Yes. Flatten PDF on WhiskFile is completely free with no account required. Free users get 7 tasks per day with files up to 50 MB. There are no watermarks on any plan. Pro plans ($4.99/month) unlock unlimited tasks, 500 MB files, batch processing, and API access.
Yes. Flatten PDF runs entirely in your browser using WebAssembly. Your files are never uploaded to any server — they stay on your device throughout the entire process. No data is transmitted, stored, or accessible to WhiskFile or any third party.
Yes. Flatten PDF works on any device with a modern browser — iPhone, Android, iPad, tablets, Chromebooks, and desktop computers. No app download required. The interface adapts to your screen size automatically.
Flatten PDF accepts PDF files as input and produces PDF output. The maximum file size is 50 MB on the free plan (500 MB for Pro users). There are no page count limits.
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