Shottr - Shottr is a free macOS screenshot app with scrolling screenshots, OCR, annotation and measurement instruments.
Microlink screenshot - Take a screenshot of any website
Full Page Screen Capture - I built a Chrome Extension that allows you to save a screenshot of an entire webpage as an image
Thum.io - A real-time website screenshot generator
Webshot - Free and Open Source screenshot website service
LambdaTest - Perform Web Testing on 2000+ Browsers & OS