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Now, these are some useful extensions that I've been using in Chrome to help me to develop webapps:
- 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.
- 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.