Webshot - Free and Open Source screenshot website service
Screenstab - A tool to turn ordinary screenshots into beautiful image assets
App Screenshot Maker - Design marketing screenshots for your app in minutes
Thum.io - A real-time website screenshot generator
Geekflare Screenshot API - Take a full page screenshot of any site from multiple locations whether it be via desktop, mobile or tablet
GoFullPage - GoFullPage is an all-in-one browser extension for Chromium, Firefox, Opera, and Chrome that lets you capture screenshots for page layouts.