Useful Chrome extensions to developers

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Now, these are some useful extensions that I've been using in Chrome to help me to develop webapps:
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• Dimensions: A tool for designers to measure screen dimensions
• Full Page Screen Capture: Screen capture your current page in entirety and reliably!
• Google Analytics URL Builder: This extension is a hyper version of Google Analytics URL Builder and tag URL's to be tracked in Google Analytics Campaign reports. Also, you can create shortlinks using your bit.ly account.
• HTTP/2 and SPDY indicator: An indicator in the address bar for HTTP/2 and SPDY support by each website.
• JSONView: An useful extension to format JSON files.
• JSON Editor: JSON Editor is a tool to view, edit, and format JSON. It shows your data in an editable treeview and in a code editor.
• Kingsquare HTML Validator: A HTML5 validation library, using a JavaScript port of the TIDY library
• Mobile/Responsive Web Design Tester: Test responsive web designs or mobile pages that detect specific user agents
• Postman – REST Client: Postman helps you be more efficient while working with APIs.
• RailsPanel: Devtools panel for Rails development. It requires meta_request gem.
• Tabs saver: It allows to save your opened tabs to future use.
• Wappalyzer: It detects technologies used on websites. It's very interesting for curious people.
• Window Resizer: Resize browser window to emulate various screen resolutions. It is useful because you can set dimensions without worries like toolbar's height.
• YSlow: Make your pages faster with Yahoo!'s page performance tool.