Mobilizon can use some 3rd-party pictures as illustrations. Right now it's only used as a illustration for the city/region the user has been located to. Only Unsplash is supported at the moment.
You need to get an API Key from Unsplash. Unreviewed apps are only allowed 50 requests per hour.
config :mobilizon, Mobilizon.Service.Pictures.Unsplash, app_name: "Mobilizon", access_key: "your-unsplash-API-key", csp_policy: [ img_src: ["images.unsplash.com"]