Add text to Existing PDF using Python

I know this is an older post, but I spent a long time trying to find a solution. I came across a decent one using only ReportLab and PyPDF so I thought I'd share:

1. read your PDF using PdfFileReader(), we'll call this input
2. create a new pdf containing your text to add using ReportLab, save this as a string object
3. read the string object using PdfFileReader(), we'll call this text
4. create a new PDF object using PdfFileWriter(), we'll call this output
5. iterate through input and apply .mergePage(*text*.getPage(0)) for each page you want the text added to, then use output.addPage() to add the modified pages to a new document

This works well for simple text additions. See PyPDF's sample for watermarking a document.

Here is some code to answer the question below:

packet = StringIO.StringIO()
can = canvas.Canvas(packet, pagesize=letter)
<do something with canvas>
can.save()
packet.seek(0)
input = PdfFileReader(packet)

From here you can merge the pages of the input file with another document.

Don't use mergePage, It may not work for some pdfs You should use mergeRotatedTranslatedPage

from PyPDF2 import PdfFileWriter, PdfFileReader
import io
from reportlab.pdfgen.canvas import Canvas

page_to_merge = 0 #Refers to the First page of PDF 
xcoor = 250 #To be changed according to your pdf
ycoor = 650 #To be changed according to your pdf

input_pdf = PdfFileReader(open("Source.pdf", "rb"))
page_count = input_pdf.getNumPages()
inputpdf_page_to_be_merged = input_pdf.getPage(page_to_merge)

packet = io.BytesIO()
c = Canvas(packet,pagesize=(inputpdf_page_to_be_merged.mediaBox.getWidth(),inputpdf_page_to_be_merged.mediaBox.getHeight()))
c.drawString(xcoor,ycoor,"Hello World")
c.save()
packet.seek(0)

overlay_pdf = PdfFileReader(packet)
overlay = overlay_pdf.getPage(0)

output = PdfFileWriter()

for PAGE in range(page_count):
    if PAGE == page_to_merge:
        inputpdf_page_to_be_merged.mergeRotatedTranslatedPage(overlay, 
                inputpdf_page_to_be_merged.get('/Rotate') or 0, 
                overlay.mediaBox.getWidth()/2, overlay.mediaBox.getWidth()/2)
        output.addPage(inputpdf_page_to_be_merged)
    
    else:
        Page_in_pdf = input_pdf.getPage(PAGE)
        output.addPage(Page_in_pdf)

outputStream = open("destination.pdf", "wb")
output.write(outputStream)
outputStream.close()

If you're on Windows, this might work:

PDF Creator Pilot

There's also a whitepaper of a PDF creation and editing framework in Python. It's a little dated, but maybe can give you some useful info:

Using Python as PDF Editing and Processing Framework

You may have better luck breaking the problem down into converting PDF into an editable format, writing your changes, then converting it back into PDF. I don't know of a library that lets you directly edit PDF but there are plenty of converters between DOC and PDF for example.