Extract PDF form data
Read every AcroForm field name, type and value out as JSON.
Runs on your device. The file is never uploaded.
Extract PDF form data reads every AcroForm field and prints a JSON object keyed by field name, each entry carrying a type and the current value. It is indented two spaces and saved as -formdata.json. Only the type and value are recorded, so a field's page, position and permitted options are not.
Questions
What do I get out?
A JSON object keyed by field name, where each entry has a type and a value. Text fields report type text with their string, checkboxes report checkbox with true or false, and dropdowns, option lists and radio groups report their current selection. It is pretty-printed with two-space indentation and saved with a -formdata.json suffix.
Does it upload the form to read it?
No. pdf-lib parses the AcroForm in a Web Worker in this tab and builds the JSON there. Completed forms usually hold personal information, so nothing is transmitted, nothing is cached on a server, and the tool works with your network disconnected.
Why does it say "this PDF has no form fields"?
Because pdf-lib found no AcroForm fields in the document. A PDF that looks like a form but was printed or flattened has none: the boxes are drawn on the page rather than being real widgets. There is nothing to extract in that case, so the tool stops instead of writing you an empty object.
What if a field type is not one it knows?
It is still listed. Anything outside the five known types is written out with pdf-lib's own class name as its type and a null value, so you can see the field exists even though its value was not read. Nothing is silently dropped from the output.
Can I use the output to fill another copy of the form?
Almost. The names are right but the shape is not: this writes name to an object with type and value, while Fill PDF form wants name straight to value. Strip the type wrapper and you have your input. Extracting first is still the fastest way to learn a form's exact field names.
Is the preview the same as the file?
Yes, byte for byte. The JSON shown on the page is the exact content written into the download, so you can read it, copy it out of the page and skip the file entirely if that is easier. One PDF at a time; run it again for the next.