Twitter's six-second video app, Vine, is now available on the Amazon App Store, therefore exposing Kindle Fire users to the service for the first time. 

Vine landed in the store on Monday, a week after the Android version launched front camera support. The timing isn't coincidental, of course, as the Kindle Fire HD has only a front-facing camera.

Read: Twitter adds genres to #Music for iOS, front camera support to Vine for Android

The app's availability on the Amazon App Store is also interesting because Instagram, a similar 15-second video app from Facebook, doesn't have a Kindle Fire app. Moreover, analytics firm Topsy, as first noted by Marketing Land, recently revealed that Instagram was now more popular than Vine. The data came from the number of shared links on Twitter.

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Vine's launch on the Amazon App Store is likely Twitter's attempt to bolster growth and hook Kindle Fire users before Instagram has the chance - especially now the Android app has camera support for plenty of selfies.