About FormFlatten
FormFlatten is a PDF form filler and flattener that runs in the browser tab you are reading this in. It opens a PDF, finds the interactive form inside it, shows every field where it actually sits on the page, and writes your answers back into the file — either keeping the form editable or flattening it so the values become permanent page content.
It exists because the forms people fill in are rarely trivial documents. A tenancy application, a tax declaration or a school enrolment form carries a name, an address, a personal identification number and sometimes a bank account — exactly the data you should not paste into an anonymous website that promises to email you the result. Here the PDF is read with pdf.js and rewritten with pdf-lib inside your browser: there is no upload, no temporary storage, no account and no analytics script. Close the tab and the document is gone from the page along with everything you typed.
It is built and maintained by Interhive OÜ, a small studio in Tallinn that makes tiny, dependable web tools.
What it does
- Reads the real AcroForm
Text fields (single line, multiline, combed, length-limited), checkboxes, radio groups, dropdowns, option lists, push buttons and signature fields — each with its PDF name, widget rectangles, font size and flags.
- Three ways to save
A filled PDF that stays editable, a flattened PDF whose values are page content, and a flattened PDF whose pages have been re-rendered as images for maximum compatibility.
- Signatures and free text
Draw a signature with a mouse, finger or stylus, or upload a photo of one and drop its white background. PDFs with no form fields at all can still be written on with hand-placed text boxes.
- Values in and out
Export what you typed as JSON or CSV, and fill a form from a JSON file of field names — useful when you send the same form every month.
Honest limits
FormFlatten does not open password-protected or certified-signed PDFs, and it does not support XFA (LiveCycle) forms — those need Adobe's own software. A drawn signature is an image of your handwriting, not a cryptographic digital signature, so it carries the same weight as signing a printed page. And flattening is one-way: keep the original file if you may need to change an answer later.
Get in touch
Found a form this tool reads wrong, or a field type it misses? Send us the form if you can share it — we read everything.
support@interhive.org