How to convert a PDF from base64 string to a file?


I have a PDF as a base64 string and I need to write it to file using Python.
I tried this:

import base64

base64String = "data:application/pdf;base64,JVBERi0xLjQKJeHp69MKMSAwIG9iago8PC9Qcm9kdWNlciAoU2tpYS9..."

with open('temp.pdf', 'wb') as theFile:

But it didn’t create a valid PDF file.
What am I missing?

Asked By: Rafael Miller



From my understanding base64decode only takes in a base64 string and looks like you have some headers on your string that are not encoded.

I would remove “data:application/pdf;base64,”

check out the doc here:

When I’ve used it in the past, I have only used the encoded string.

Answered By: Mark

Does writing it by using the codecs.decode function work?
also as Mark stated, you can try to remove the data:application/pdf;base64, portion of the string as this section of the string is not to be decoded.:

import codecs
base64String = "JVBERi0xLjQKJeHp69MKMSAwIG9iago8PC9Qcm9kdWNlciAoU2tpYS9..."

with open("test.pdf", "wb") as f:
    f.write(codecs.decode(base64string, "base64"))
Answered By: Jebby

This is not just base64 encoded data, but data-uri encoded:

There is another post on stack overflow asking how to parse such strings in Python:

How to parse data-uri in python?

The gist of it is to remove the header (everything up to and including the first comma):


NOTE: I use [1:2] instead of [1] because it won’t throw an exception if there is only 1 element in the list because nothing follows the comma (empty data).

Answered By: Forest Darling

Extending @Jebby‘s answer using Base64 (had the same issue as @SmartManoj)

import base64
base64String = "JVBERi0xLjQKJeHp69MKMSAwIG9iago8PC9Qcm9kdWNlciAoU2tpYS9..."

with open("test.pdf", "wb") as f:
Answered By: Dfranc3373

Here is my solution::–

from base64 import b64decode

def base64_to_pdf(file):
    file_bytes = b64decode(file, validate=True)
    if file_bytes[0:4] != b"%PDF":
        raise ValueError("Missing the PDF file signature")

    with open("file.pdf", "wb") as f:
        return f.write(file_bytes)
Answered By: Mohd Shoaib
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