As long as you develop on your local machine, the world is nice and you are probably the only client asking for something which is probably most of the time a correct request. If you are releasing your code to the internet, you will face a lot of bots and wrong requests and automated tools to find bugs in your app. See some logs of our CartoX API running in the Internet: INFO:werkzeug:104.152.52.61 – – [31/Dec/2018 08:33:06] “GET / HTTP/1.0” 200 – ERROR:werkzeug:104.152.52.61 – – [31/Dec/2018 08:33:06] code 400, message Bad request syntax (‘HELP’) INFO:werkzeug:104.152.52.61 – – [31/Dec/2018 08:33:06] “HELP” HTTPStatus.BAD_REQUEST – ERROR:werkzeug:104.152.52.61 – – [31/Dec/2018 08:33:11] code 400, message Bad request syntax (‘DmdT\x00\x00\x00\x17\x00\x00\x00\x01\x00\x00\x00\x00\x11\x11\x00ÿ\x01ÿ\x13’) INFO:werkzeug:104.152.52.61 – – [31/Dec/2018 [...]