List of free screenshots stuff for developerππ½
If you're looking for all programming tools around screenshots (not just free). Check this page List of screenshots Programming Tools

Puppeteer
Most things that you can do manually in the browser can be done using Puppeteer
Tag: screenshots, ui-testing, crawl

Refero - design references for your next project
The biggest collection of design references from great web applications
Tag: design, inspirations, web apps, screenshots
Free tier after sign up