Google Photos vs ReSmush.it

Google's Photos APIs let apps read from and write to a user's Google Photos library across three products: the current Picker API lets a user securely choose individual items to share without granting an app full library access, the older Library API supports app-driven uploads and management of app-created content (several of its broader read scopes were removed on April 1, 2025), and the newer Ambient API drives slideshow experiences on photo frames and connected TVs. Every product requires OAuth2 user consent — there is no server-only API-key path — governed by Google's Photos API User Data and Developer Policy. Usage is free, bounded by per-project quotas that vary by product (for example 100,000 requests/minute for the Picker API versus 10,000/day for the Library API).

ReSmush.it is a free, keyless image-optimization API — best known as the backend behind the ReSmush.it WordPress plugin — that accepts a source image URL and returns a JSON payload with the compressed image's URL plus original size, compressed size, and percent reduction. A live call against api.resmush.it needed no credentials and returned Access-Control-Allow-Origin: *, so it works directly from browser JavaScript. The plain http:// endpoint immediately redirects to https, so the service is https-only despite requiring no API key.