The URL used in this tutorial is Un air sain pour tous | Atmo France (with the department at the end).
If you find a city-level API, I’d be interested 
Thanks, the URL is even available in the JSON configuration 
.
My question was how this URL was found to access documentation or something to modify it and get the data by city 
(cf: how you found the pollen API endpoint)
Hello,
It doesn’t seem to me that you can get the data by city; I haven’t looked into the matter.
I simply found it through what’s done in Home Assistant, in particular at the following link:
https://www.skipcool.ovh/2021/02/27/recuperer-les-informations-de-pollens-fr-dans-homeassistant/