PDF Forms: Read and Fill AcroForm Fields with Python

PDF Forms: Read and Fill AcroForm Fields with Python

Interactive PDF forms (AcroForm) are common in official documentation, contracts, and applications. Python lets you read, fill, and create them automatically.

AcroForm Field Types

Read Form Fields with pypdf

pip install pypdf

from pypdf import PdfReader

reader = PdfReader("form.pdf")

# Text fields
fields = reader.get_form_text_fields()
for name, value in fields.items():
    print(f"  {name!r}: {value!r}")

# All field types
for name, field in reader.get_fields().items():
    field_type = field.get('/FT', '?')
    value = field.get('/V', '')
    print(f"  [{field_type}] {name}: {value}")

Fill an Existing Form

from pypdf import PdfReader, PdfWriter

reader = PdfReader("blank_form.pdf")
writer = PdfWriter()
writer.append(reader)

data = {
    "full_name": "Maria Garcia",
    "id_number": "12345678A",
    "email":     "maria@example.com",
    "city":      "Madrid",
}

for page in writer.pages:
    writer.update_page_form_field_values(page, data)

with open("filled_form.pdf", "wb") as f:
    writer.write(f)
print("Saved: filled_form.pdf")

Checkboxes and Radio Buttons

data = {
    "name":         "John Smith",
    "accept_terms": "Yes",       # Checkbox: "Yes" = checked
    "gender":       "/Male",     # RadioButton: widget value
    "country":      "US",        # ComboBox: option value
}
for page in writer.pages:
    writer.update_page_form_field_values(page, data)

Create PDF Form from Scratch with reportlab

pip install reportlab

from reportlab.pdfgen import canvas
from reportlab.lib.pagesizes import A4

def create_form(output="new_form.pdf"):
    c = canvas.Canvas(output, pagesize=A4)
    width, height = A4

    c.setFont("Helvetica-Bold", 18)
    c.drawString(50, height - 60, "Registration Form")

    c.setFont("Helvetica", 12)
    c.drawString(50, height - 110, "Full Name:")
    c.acroForm.textfield(name="full_name", x=200, y=height-120, width=300, height=20)

    c.drawString(50, height - 150, "Email:")
    c.acroForm.textfield(name="email", x=200, y=height-160, width=300, height=20)

    c.drawString(50, height - 200, "Accept terms:")
    c.acroForm.checkbox(name="accept_terms", x=210, y=height-210, buttonStyle="check")

    c.drawString(50, height - 250, "Country:")
    c.acroForm.choice(
        name="country",
        options=[("US","United States"),("GB","UK"),("CA","Canada"),("AU","Australia")],
        x=200, y=height-260, width=200, height=20, value="US",
    )

    c.drawString(50, height - 300, "Gender:")
    c.acroForm.radio(name="gender", tooltip="Male", x=200, y=height-310,
                     buttonStyle="circle", value="Male")
    c.drawString(225, height - 305, "Male")
    c.acroForm.radio(name="gender", tooltip="Female", x=300, y=height-310,
                     buttonStyle="circle", value="Female")
    c.drawString(325, height - 305, "Female")

    c.save()
    print(f"Form created: {output}")

create_form()

Fill with pdfrw

pip install pdfrw

import pdfrw

def fill_pdfrw(input_path, output_path, data):
    template = pdfrw.PdfReader(input_path)
    for page in template.pages:
        annotations = page.get('/Annots') or []
        for a in annotations:
            if a.get('/Subtype') == '/Widget' and a.get('/T'):
                name = a['/T'][1:-1]
                if name in data:
                    a.update(pdfrw.PdfDict(V=data[name], AP=''))
    template.Root.AcroForm.update(pdfrw.PdfDict(NeedAppearances=pdfrw.PdfObject('true')))
    pdfrw.PdfWriter().write(output_path, template)
    print(f"Saved: {output_path}")

fill_pdfrw("template.pdf", "filled.pdf", {
    "name": "Anna Torres",
    "email": "anna@example.com",
})

Flatten the Form (Form to Static)

# Method 1: pypdf
from pypdf import PdfReader, PdfWriter
reader = PdfReader("filled_form.pdf")
writer = PdfWriter()
for page in reader.pages:
    writer.add_page(page)
with open("flattened.pdf", "wb") as f:
    writer.write(f)

# Method 2: Ghostscript (more faithful)
import subprocess
subprocess.run([
    "gs", "-dNOPAUSE", "-dBATCH", "-sDEVICE=pdfwrite",
    "-dFlattenForm", "-sOutputFile=flattened_gs.pdf", "filled_form.pdf"
], check=True)

Extract Data from Filled Form

from pypdf import PdfReader
import json

reader = PdfReader("filled_form.pdf")
extracted = {}
for name, field in reader.get_fields().items():
    value = field.get('/V', '')
    if hasattr(value, 'get_object'):
        value = str(value.get_object())
    extracted[name] = str(value) if value else ""

print(json.dumps(extracted, indent=2))

Tools for Creating Form Templates

Convert Online

To fill or extract data from PDF forms without Python, KaijuConverter processes PDFs directly in the browser.

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