PDF Form Filler
Fill the interactive form fields of a PDF from a JSON object that maps field names to values. Text fields take strings, checkboxes take true or false, and radio groups, dropdowns and list boxes take one of their options. Unknown field names are reported by name before anything is written, and you can flatten the filled form so the values become fixed page content.
Frequently asked questions
How do I write the values?
As a JSON object whose keys are the full field names and whose values are the content, for example {"name": "Ada Lovelace", "subscribe": true, "country": "UK"}. Use the PDF Form Fields tool to see the exact names. The object can hold up to 1,000 fields.
Which values does each field type accept?
Text fields accept strings and numbers. Checkboxes accept true or false, and also yes, no, on, off, 1 and 0. Radio groups need one of their option names, dropdowns and list boxes need one of their options or, if they allow several, an array of options, and an editable dropdown accepts any text.
What happens with a misspelled field name?
Nothing is filled. The tool checks every name first and answers with a message that lists the names it could not find, so you can correct them and try again.
What if a value does not fit its field?
A text longer than the maximum length of the field, an option the field does not offer or a value of the wrong kind is refused with a message that names the field. Button and signature fields cannot be filled and are refused the same way.
What does the flatten option do?
It turns the filled fields into ordinary page content after filling, so the values can no longer be edited and look the same in every viewer. Leave it off to keep the form editable.
Which characters can I fill in?
Latin text uses Helvetica. When a value contains characters outside that font, such as Greek or Cyrillic, the field appearances are drawn with an embedded subset of Inter. Characters neither font covers, such as Chinese, are refused with a message that lists them.
Do the fields I leave out change?
No. Only the fields named in the JSON are changed, and every other field keeps its current value.
Are XFA forms supported?
No. Only standard AcroForm fields can be filled. XFA data, which this engine cannot edit, is removed so that viewers show the AcroForm fields with the new values.
Can I fill a password protected PDF?
Yes, enter its password in the password field. The filled PDF is saved without the password, and the password is not returned.
What are the limits?
PDFs up to 10 MiB and 200 pages, a JSON text up to 100,000 characters with at most 1,000 fields, and 30 seconds of processing. The filled PDF can be up to 32 MiB.