Even if you define the url
properly by assigning the given URL:
import requests
url = "https://www.upiqrcode.com/iban-generator/de/germany"
datas = {}
GetInfo = requests.post(url, data=datas)
decodeResponse = GetInfo.content.decode("utf-8")
print(decodeResponse)
You would end up getting HTML as response, which correctly prints on console.
Record the form-submission and watch POST request in browser
Instead, figure out how and where the form-data is POSTed. Do this by opening the browsers Developer Console (usually F12) and viewing the Network tab, before clicking submit button (here "Calculate") on the form.

You can even right-click on the request there an Copy > as CURL. Then paste that in a text-editor or on the command-line to reproduce.
curl 'https://www.upiqrcode.com/get-iban-number' \
-H 'User-Agent: Mozilla/0.0 (OS) Gecko/20210808 Firefox/0.0' \
-H 'Accept: text/html, */*; q=0.01' \
-H 'Accept-Language: en-US,en;q=0.5' --compressed \
-H 'Content-Type: application/x-www-form-urlencoded; charset=UTF-8' \
-H 'X-Requested-With: XMLHttpRequest' \
-H 'Origin: https://www.upiqrcode.com' \
-H 'Connection: keep-alive' \
-H 'Referer: https://www.upiqrcode.com/iban-generator/de/germany' \
-H 'Sec-Fetch-Dest: empty' \
-H 'Sec-Fetch-Mode: cors' \
-H 'Sec-Fetch-Site: same-origin' \
-H 'Sec-GPC: 1' \
--data-raw 'country=DE&bank=37040044&branch=&account=0532013000&ip=0.0.0.0'
Note: I have broken into several lines for readability (thus the \
at line ends). For privacy protection I have anonymized data like User-Agent and IP in the request above.
Even when anonymized like this, the request sent via cURL on the command-line, you get a response (HTML snippet) with the expected IBAN:
<h4 class="text-center text-success">IBAN Electronic Format :DE89370400440532013000</h4><h4 class="text-center text-success">IBAN Paper Format :DE89 3704 0044 0532 0130 00 </h4>
Reproduce in Python
Now you can rebuild this POST-request in Python.
What we need is:
- some request-headers like
'Content-Type: application/x-www-form-urlencoded; charset=UTF-8'
- the posted data:
'country=DE&bank=37040044&branch=&account=0532013000&ip=0.0.0.0'