How to use Fill PDF Form
- Select a fillable PDF form.
- Fill in the fields listed on screen.
- Tick “Flatten” if the recipient should not change your answers, then save.
Fillable vs. flat forms
This tool works with PDFs that contain real form fields (AcroForms). If your PDF is just a printed form with lines to write on, use Edit PDF to type text anywhere on the page, and Sign PDF to add a signature.
Form fields use the standard PDF fonts, which only cover Latin characters; for Chinese or other scripts, use Edit PDF instead.
🔒 Your files never leave your device
bopdf processes your documents locally with JavaScript (pdf-lib and Mozilla pdf.js) inside your browser tab. Your PDF is never uploaded, stored or seen by us — you can even disconnect from the internet after the page loads and the tool keeps working. When you close the tab, everything is gone.
Frequently asked questions
Why are no fields shown?
The PDF has no interactive fields. Use Edit PDF to type on it.
What does flatten mean?
Your answers become part of the page and can no longer be edited.
Are my files uploaded to a server?
No. Everything happens in your browser on your own device. Files are never sent over the internet, which makes bopdf suitable for confidential documents.
Is there a file size limit?
There is no fixed limit, but very large files (hundreds of MB) depend on your device memory. On phones, files up to about 100 MB usually work well.