A developer who claims to have access to the next major release of Windows Phone has spilled the beans on Reddit. Based on this leak, which appears to be legit, Windows Phone 8.1 will offer many changes when compared to the current shipping version of the OS, Windows Phone 8 with Update 3.

This list is based on the Reddit leak, but I've added my own notes and context where possible.

April release. Windows Phone 8.1 and a new SDK for developers is due April 2, according to the leak. Since that's when BUILD is happening, and I've previously (and exclusively) reported that BUILD will focus on Windows Phone and Xbox One, that date makes sense.

Universal apps with HTML/JavaScript. The leaker claims that developers will be able to create so-called Universal apps with HTML and JavaScript that can run on both Windows 8.x and Windows Phone 8.1.

Battery Sense. A new Battery Sense app will help you see which apps are using up the battery.

Xbox Music and Xbox Video. They are replacing the Music & Video hub.

Podcast app. With the Music & Video hub being removed and Microsoft creating separate Xbox Music and Xbox Video apps, many are wondering about podcast support. According to the leak, Windows Phone 8.1 will include a new standalone Podcast app, which is unexpected.

Camera app. The Camera app has been redesigned. Surprised it's not just the Pro Camera app from Nokia.

Bing apps. A full slate of Bing apps are now installed by default, as they are in Windows 8.1: Bing Finance, Bing Food & Drink, Bing Health & Fitness, Bing News, Bing Sports Bing Travel, and Bing Weather.

VPN support. We knew this was coming, but Windows Phone 8.1 will provide the same type of built-in VPN support as does Windows 8.1. Which is to say, not the VPN support everyone needs: Cisco.

Wi-Fi Sense app as a sort of accompaniment to Data Sense, Battery Sense, and ... Storage Sense.

OneDrive. SkyDrive has been rebranded as OneDrive throughout Windows Phone 8.1, as it has in Windows 8.1 Update 1. And the OneDrive app now supports local file system browser, as it does in Windows.

SD card support. There is much better support for micro-SD cards in Windows Phone 8.1. In addition to digital media content, you can now install apps to the card, using the Storage Sense setting, above.

Command bar. Not a huge deal, but it appears that the name "app bar" is being replaced by "command bar."

App lifecycle maintenance. Mobile apps are managed by the OS as they are in Windows RT. So tapping the Back button no longer kills an app. (I'm not 100 percent sure it ever did that, but whatever.) Multitasking will be "more efficient." You can swipe down to close apps from the multitasking screen, as you can on other mobile OSes. (The close boxes are still there too.)

App auto-updating, just like Windows 8.1.

New tile sizes. As was the case with Update 3, Windows Phone 8.1 will again support new tile sizes, no doubt related to ever-bigger screen resolutions.

File Picker has been redesigned. There's a File Saver now as well.

YouTube app. Hope springs eternal, I guess.

Xbox Games hub has been redesigned.

Quick Settings menu (Wi-Fi, Bluetooth, etc.) by swiping down from the top of the screen.

Action Center menu by swiping up from the bottom of the screen. Some are reporting that this is the Notification Center, but I'm hearing it's a different feature.

PlayTo and screen mirroring support. Nokia currently offers a PlayTo app for Lumia owners, and various screen mirroring apps for that matter.

Not surprisingly, Microsoft has nothing concrete to say on the record, but it vaguely addressed the notion that it may have recently shared Windows Phone 8.1 information with external developers.

"We regularly involve our developer community in a variety of private programs," a Microsoft statement notes. "We have nothing to share broadly about our recent developer outreach."

More as it comes in...