Google is firming up a tool that should help programmers bridge the divide between Android phones and iPhones.

It's hard to write software that matches the appearance of both Apple's iOS software and Google's Android operating system, which is one reason developers often hire separate teams to create two versions of the same product. Google, though, is finishing up a tool called Flutter that gives apps a native look for either mobile realm. It can also shuck conventional looks for something totally different.

The search giant announced the release of the initial Flutter beta at the Mobile World Congress show on Tuesday. New updates should arrive every four weeks or so as Google and others contributing to the open-source project put the finishing touches on an eventual -- though still unscheduled -- 1.0 release.

Flutter could help usher in a wave of fresh-looking apps in an era when lots of mobile software suffers from cookie-cutter similarities. Most apps today use native components, such as buttons and text boxes, that are styled to match the core software from Apple or Google. Flutter's interface widgets can follow that styling but also can go in very different directions.

"The brand identity and customization of the app's aesthetic design is now becoming more important than strictly adhering to traditional platform aesthetics," Google says in its Flutter FAQ. "For example, app designs often require custom fonts, colors, shapes, motion, and more in order to clearly convey their brand identity."

Customized app interfaces

Mobile apps from Snapchat, Hulu, Netflix, Uber and PayPal show developers have started to break free of traditional app interfaces even before Flutter, says program manager Seth Ladd.

"We believe developers and brands will really take advantage of Flutter's framework to gain control over their user interface and clearly articulate their brand identity across devices," Ladd said.

Google already uses Flutter to build its AdWords app, and the Hamilton musical app is another prominent convert. Flutter apps use Google's Dart programming language, but they can connect to existing software written in more common languages, such as Java in the case of Android and Swift or Objective-C in the case of iOS.

"Dart is approachable and easy to learn" for anyone with experience with mainstream programming languages like Oracle's Java, the web's JavaScript, Apple's Swift, Adobe's ActionScript and Microsoft's C#, Ladd said.

Hello, Fuchsia

There's one more interesting thing about Flutter: it's core to Fuchsia, a new operating system Google is building. Fuchsia is still in early stages of development, and isn't a project for the faint of heart. But as Flutter matures and attracts more programmers, things could go more smoothly for Fuchsia.

That's because app developers will be able to easily generate a Fuchsia version of their software alongside whichever other versions they're already producing. The biggest challenge for new operating systems is attracting a critical mass of software, so that's important.

But for now, Google's Flutter sales pitch is sticking to nearer-term benefits -- a unified developer team, fast testing of software, flexible styling choices and high performance when the app is running. 

First published Feb 2:41 p.m. PT.
Update, 4:17 p.m.: Adds comment from Flutter leader Seth Ladd.