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Fluent is a web-based workflow stream that works with existing Gmail accounts to bring a Sparrow-like user interface to email.

Users can stream email threads and replies, preview aggregated attachments in a tab, quickly reply or compose inline, archive messages, and even add a to-do list with the new design concept that claims to run on any web browser.

Sparrow is a great success as a Mac-only application, and now Fluent hopes to balance the playing field and snag users whom are in dire need of a new Gmail look and functionality. Fluent’s website specifically praises its workflow ability, multiple accounts options, and “blazing” fast search-as-you-type filter.

The streaming email UI is the work of three former Googlers who quit the Mountain View, Calif.-based Company. BusinessInsider said Cameron Adams, Dhanji Prasanna, and Jochen Bekmann left because designers were “less valuable” than engineers at Google, and they felt disconnected from Google’s culture while operating from across the world in Sydney, Australia…

On Fluent’s Tumblr blog, the founders explained they left Google to fulfill a product vision based on six principles: Simple conversations, Streamlined workflow, access anywhere, beautiful design, seamless experience for desktops, small screens and touch devices, and communicating in the best way possible.

The departure seems fruitful. They invested their time into making the “future of email,” and soon gave birth to a concept that clearly draws cues from a variety of email and social network app designs, including Sparrow, Facebook, and Tweetie.

The service is in closed beta now and only has a demo account available, but those interested can easily sign up for an invite when Fluent launches. It is worth noting that some have mentioned running into a Java error message when attempting to launch the demo version.

This article is cross-posted on 9to5Google.