Python 3 script to extract images from HTTP Archive (HAR) files (Tested & working on Python 3.11)

extract_har.py

import json
import base64
import os

# make sure the output directory exists before running!
folder = os.path.join(os.getcwd(), "imgs")

if not os.path.exists(folder):
    os.mkdir(folder,777)

ext = {
            "image/webp": "webp",
            "image/jpeg": "jpg",
            "image/png": "png",
            "image/svg+xml": "svg"
        }

with open("har.har", "r",encoding="utf8") as f:
    har = json.loads(f.read())

entries = har["log"]["entries"]

for entry in entries:
    mimetype = entry["response"]["content"]["mimeType"]
    filename = entry["request"]["url"].split("/")[-1]
    if mimetype in ext:
        image64 = entry["response"]["content"]["text"]
        ext.get(mimetype)
        file = os.path.join(folder, f"{filename}")
        with open(file, "wb") as f:
            f.write(base64.b64decode(image64))

Note that this gist will overwrite files with the same filename and different URL paths, since the code is not creating subfolders.

For updated version with subfolders creation and parametrised (specifiable) input file and output folder, see the fork here:
https://gist.github.com/FurloSK/0477e01024f701db42341fc3223a5d8c