Use **request.args.get(param)** :
http://10.1.1.1:5000/login?username=alex&password=pw1
@app.route('/login', methods=['GET', 'POST'])
def login():
username = request.args.get('username')
print(username)
password = request.args.get('password')
print(password)
# Below is the ref link:
[enter link description here][1]
[1]: https://flask.palletsprojects.com/en/1.1.x/api/#flask.Request.args