Contentful is an API-first CMS, offering four REST APIs for working with your content. Each of these APIs serve a different purpose, so which one to use depends on what you want to do:
images.contentful.com. You can apply various transformations to images by appending query parameters to the URL, so we refer to this as our Images API.
The Content Delivery API (CDA), available at
https://cdn.contentful.com, is a read-only API for delivering content from Contentful to apps, websites and other media. Content is delivered as JSON data; images, videos and other media are delivered as files.
The API is available via a globally distributed content delivery network. All content, both JSON and binary, is served from the server closest to where a user is requesting content from. This minimizes latency, which especially benefits mobile apps. Hosting content in multiple data centers around the world also greatly improves the availability of content.
The Content Management API (CMA), available at
https://api.contentful.com, is a read-write API for managing your content. Unlike the Content Delivery API, the management API requires you to authenticate as a Contentful user. It covers several use cases, such as:
Note: You can also use the Content Management API to retrieve content. It's used to only manage content, so it will retrieve all items (i.e. all localized and unpublished content).
The Preview API, available at
https://preview.contentful.com, is a variant of the CDA for previewing your content before you deliver it to your customers. You use the Preview API in combination with a "preview" deployment of your website (or a "preview" build of your mobile app) that allows content managers and authors to view their work in-context, as though it was published. This API uses a "preview" access token to allow you to view unpublished content as though it were delivered by the CDA.
With the Images API
https://images.contentful.com you can resize and crop images, change their background color and convert them to different formats, PNG→JPG, for instance. Using our backend for these transformations lets you upload high-quality assets, deliver exactly what your app needs, and still get all the benefits of our caching CDN.