screenshotlayer API is described as 'Screenshotlayer is a lightweight REST API built to automate the process of capturing website screenshots through your own application. Simply define your URL & choose from a full stack of customisation features, and the API will return a high quality PNG, JPEG or GIF image' and is an website. There are four alternatives to screenshotlayer API, not only websites but also apps for SaaS. The best screenshotlayer API alternative is CloudBrowser.co. It's not free, so if you're looking for a free alternative, you could try microlink.io or Screenshotbase.
There are many reasons why switched away from screenshot layer