Why you can trust us

Engadget has been testing and reviewing consumer tech since 2004. Our stories may include affiliate links; if you buy something through a link, we may earn a commission. Read more about how we evaluate products.

ZTE Open review: Firefox OS gets off to a modest but promising start

As the first Firefox OS smartphone, the ZTE Open is an ambassador for its platform: it's built to prove that web apps can do the hard work of their native equivalents. It's also geared toward first-time smartphone owners with its simple interface and an $80 unlocked price. This combination of open, standards-based software and affordable hardware sounds like a dream for both developers and newcomers alike. But is that how it works in practice? Read our review and you'll find out.


ZTE Open review a rough start for Firefox OS

The design of the Open is an exercise in minimalism. A close cousin of the Android-based Kis III, it feels like a large, smooth pebble -- albeit one covered in soft-touch plastic. It's very comfortable to hold as a result, although the thin back cover and smudge-prone 3.5-inch screen will remind you that you're using a low-end handset. ZTE does deserve some kudos for embracing Firefox's native colors -- whether you buy an Open in blue or orange, your phone is destined to stand out.

The back-to-basics philosophy extends to the controls and ports. Aside from the screen, the only features on the front are an LED (for charging only) and a capacitive home button. There's no front-facing camera, unfortunately. On the left is a volume rocker that's easy to use by feel alone; the top holds both a power button and a headphone jack, while the micro-USB port and microphone sit at the bottom. You'll find only a 2-megapixel camera and speaker on the back, although it's easy to pop off the rear cover and get access to both the 1,200mAh battery as well as the SIM and microSDHC card slots. That accessibility is essential, too, as the built-in 512MB of storage isn't enough to hold a media collection. The eBay version (available in the US and UK) doesn't officially ship with any microSD expansion, although carriers like Movistar Spain include a 4GB card in the box; we've also heard of eBay customers receiving 4GB cards.

As you've likely gathered, the Open will disappoint if you're looking for clever hardware tricks. There are no shortcut keys, notification lights or water resistance. About all you'll get for luxury is an FM radio. However, there's a refreshing simplicity to the design. It's tailor-made for newcomers to the smartphone world who don't need (or don't care for) any frills. While we wish that the components inside were more powerful, the form factor is at least appealing.

ZTE Open


114 x 62 x 12.5 mm (4.5 x 2.4 x 0.5 inches)


120g (4.2 oz)

Screen size

3.5 inches

Screen resolution

480 x 320

Screen type



1,200mAh lithium-ion (removable)

Internal storage


External storage

MicroSDHC, up to 32GB

Rear camera

2MP (fixed-focus)

Front-facing cam


Video capture

352 x 288




GSM GPRS / EDGE (850 / 900 / 1800 / 1900); HSDPA (850 / 1900)




Qualcomm Snapdragon MSM7225A


1GHz single-core ARM Cortex-A5


Adreno 200




None (USB mass storage for transfers)


Dual-band, 802.11a/b/g/n

Wireless Charging


Operating system

Firefox OS 1.1 (1.0.1 on current units)


ZTE Open review a rough start for Firefox OS

Many smartphones under $100 have very basic displays, and that's exactly what you'll get with the Open. At 3.5 inches, the LCD is a bit too small for fast typing with Mozilla's on-screen keyboard. The 480 x 320 resolution is usable, but not exactly sharp. Colors are adequate (if flat) head-on, but they wash out when you view the phone from a sharp angle. The screen is at least readable in sunlight, though.

To us, responsiveness is the display's main flaw. Despite using capacitive input, the Open's touchscreen just isn't very sensitive or accurate. It was too easy for us to miss a photo opportunity because our shutter press didn't register, or to launch an app when we meant to scroll. Even swiping down the notification bar requires a bit more effort than we're used to. The unresponsiveness is occasionally frustrating, and we'd expect better even at this modest price point.

It wouldn't take much to get a significantly improved display, either. Contrast the Open with a more expensive (if still frugal) phone like the LG Optimus L3 II: LG may have shed some screen resolution, but its display is both more responsive and produces richer colors. While ZTE doesn't have to compete in the Optimus L3 II's price bracket, it should have spent more on the screen.


ZTE Open review a rough start for Firefox OS

We'll be blunt: the Open's 2-megapixel rear camera is terrible, even by the standards of entry-level phone photography. Virtually every photo is full of blocky compression artifacts, noise and color inaccuracies. Well-lit photos in any environment are defined by purple fringing effects and blown-out highlights, while low-light images lose most of the visible detail. There's no flash to fill in that detail, and the fixed focus rules out any macro shots. We'd still take the Open's camera over none at all, but that's not exactly a compliment.

This isn't helped by the camera software, which is as rudimentary as it gets. Your options are to shoot photos, shoot videos or visit the gallery app -- and that's it. There are no settings or special modes. While there's a healthy selection of editing and sharing options in the gallery, such as cropping and exposure compensation, you'll have little input when taking the snapshot. Thankfully, Mozilla's Principal Developer Evangelist Christian Heilmann tells us that the basic feature set is due more to the hardware than the OS. We'd expect more advanced phones to get improved controls.

Just be warned that video recording is equally crude, if not more so. You can only shoot 352 x 188, 20 fps movies with single-channel sound. The image quality is decent for the resolution, but the audio is worse than a phone call. We'd use the Open's video mode only as a last resort.


ZTE Open review a rough start for Firefox OS

This is why you're reading, really. The Open is the first taste of Firefox OS for many people, including programmers who want to test their Firefox OS apps on a real device. As such, a quick explanation of the platform is in order.

At its heart, Firefox OS is a Linux variant that runs HTML5-based web apps instead of native code, even for hardware-dependent features like phone calls. Mozilla believes that its web focus liberates mobile app development; by using open standards like HTML5, developers won't be locked into supporting just one device ecosystem. It could also make smartphones more affordable, as devices won't need to store apps that primarily run online. As Heilmann explains, it's meant to deliver a smartphone experience to those who'd otherwise buy a basic cellphone -- not to become the "next iOS or Android."

It may be a while before we get Firefox OS software that feels completely at home in the modern smartphone world.

The basic experience will be familiar to anyone who has used iOS or Android, since it borrows a few concepts from both. Users get a basic home screen with a search box, a tray of customizable app shortcuts and an expandable notification bar with quick settings. Swiping to the right scrolls through your apps. Like iOS, almost every navigation element is onscreen; while that consumes extra space, it's potentially simpler for users who haven't tried (or just don't want) hardware keys. Ultimately, the interface is easy enough to understand that it takes just a few minutes to learn the ins and outs of the platform. That's no doubt the point. Mozilla wants even first-time smartphone owners to feel at home, and we'd say that the company succeeded.

That simplicity extends to the search box, which epitomizes the web-based strategy of Firefox OS. Officially known as the adaptive app search field, the box shows web results as though they were apps, not pages. Look for sushi and you'll get icons for the likes of Epicurious (for sushi recipes) or Google Maps (to find nearby sushi places). Any relevant local apps appear in the list, and you can "install" any result as an app. The approach is simple and largely works, although it may be slightly confusing to users who won't always see an explanation of where a web link will go. Thankfully, they can always use the Firefox browser to see traditional, text-based web results.

We have mixed reactions to this emphasis on web apps. The philosophy lets developers quickly port apps to Firefox OS, and lets phone makers include a lot of apps that aren't always available beyond major platforms. Our test unit shipped with third-party apps like AccuWeather, Facebook, Nokia's Here Maps, Twitter, Wikipedia and YouTube. However, this can be frustrating when you realize that most existing Firefox OS apps aren't much more capable than a mobile-optimized website. Here Maps can cache an area you're looking at for offline use, as it can elsewhere, but you can't jump over to Here Drive (like on Windows Phone) to get turn-by-turn navigation. Accordingly, you tend to lose major functionality present in native apps on other platforms, like most forms of push notifications and inter-app communication. Mozilla tells us that cross-app support is rolling out, and that app notifications will come in the OS' 1.2 upgrade; still, it may be a while before we get Firefox OS software that feels completely at home in the modern smartphone world.

DNP ZTE Open review Firefox OS gets off to a modest but promising start

It's difficult to realize exactly what you're missing, as there aren't many apps in the Firefox Marketplace, Mozilla's official store. While that's somewhat forgivable given the web push and Firefox OS' limited market presence, it also leaves us hard-pressed to find the big-name apps that we like. Right now, many Firefox OS programs are filling holes left by better-known titles: Check-In Fox replaces Foursquare, for example, while Sketchbook Squad substitutes for Doodle Jump. We have noticed major releases like Pulse and SoundCloud, but they're in the minority. Discovery is limited to finding the newest or most popular apps in a given category. Although Firefox Marketplace will undoubtedly grow in the months ahead, it currently doesn't hold a candle to mature app portals like the App Store, Google Play or the Windows Phone Store.

The OS itself is equally young. The Open unit we received is running a pre-release version of Firefox OS 1.1, which introduces surprisingly basic features like MMS and a search option in the music app. The phones on the market as of this writing are still using 1.0.1, and there's no word on whether or not they'll get 1.1 or later. Mozilla says that it can push security fixes itself -- an important advantage over some platforms -- but that bigger updates will usually require carrier or manufacturer approval. Regardless of the OS version, many of the stock apps include only the bare essentials. You can't put a video on repeat, for instance, and media syncing is limited to copying files in USB mass storage mode. Concepts like NFC and voice recognition just don't exist in Firefox OS at this stage, and there's no guarantee that they will, given the focus on low-cost, open technology. Firefox OS may be a great introduction to smartphones, but it's limiting for seasoned users.

Performance and battery life

DNP ZTE Open review Firefox OS gets off to a modest but promising start

Gauging the Open's performance is far trickier than it is with other devices. It's not just that we're looking at our first Firefox OS device, which prevents many direct comparisons; it's also that there are very few benchmarking tools. Still, there's enough here to give a clear indication of how well ZTE's handset deals with common tasks.

Mozilla needs more capable hardware to demonstrate Firefox OS' potential.

Getting around the OS is smooth enough. Although the Open is running on just a 1GHz, single-core Snapdragon MSM7225A and 256MB of RAM, the home screen, browser and many apps are mostly stutter-free. The hardware could keep up with a few 2D action games, too. Just don't expect a media powerhouse. We couldn't play H.264-encoded 720p video, and there aren't yet 3D games available (though WebGL makes these possible).

More importantly, browsing -- Firefox OS' very reason for being -- falls a bit short. Everyday web surfing is fine, but more sophisticated pages and web apps either take a while to load or periodically bog down. That subjective experience is supported by our web benchmarking. The Open took 3,665ms to complete the SunSpider JavaScript test, or more than twice as long as the Lumia 520 (1,400ms). It's more comparable to the 2009-era Motorola Milestone, better known as the GSM equivalent to the Droid; it wasn't much slower at 4,628ms. We tried other web tests to play it safe, and the results were less than flattering. Kraken, Mozilla's own JavaScript benchmark, took 67,371ms to complete where a Moto X we have on hand (admittedly, well beyond the Open's league) can finish that same test in 9,295ms. Google's Octane wouldn't even run on the Open -- it took several tries just to reach the page without an error, and the phone would invariably give up partway through.

Cellular data is also an issue. We're not concerned about the Open's modest HSPA speeds, which on Canada's Telus network averaged about 3.1 Mbps for downloads and 1.3 Mbps for uploads. It's the reception that sours the experience. The Open is very sensitive to signal changes, and it's considerably more likely to drop its data link (at least in Ottawa) where other devices using the same 3G service work properly. When a phone that absolutely needs a good internet connection has trouble sustaining that connection, there's a serious problem.

ZTE Open review Firefox OS gets off to a modest but promising start

Battery life, on the other hand, is superb. Whatever gripes we might have with the basic software feature set, it keeps the Open running for a long time on a small lithium-ion pack. We couldn't run our usual looping video test, but it was easy to last through a day of moderate-to-heavy use that included several checks of both Facebook and Twitter, a similar amount of browsing, a 20-minute call, 20 photos and two short videos. Based on less-strenuous use after our formal testing, we could see the Open lasting for two or even three days without a fresh charge.

Call quality is also good. In reasonably quiet situations, both ends of the call are loud and generally quite clear. There's no noise-canceling microphone, though, so you'll have to shout if you're in a loud environment. The rear speaker puts out sound at moderate volumes, and it isn't anything to write home about.


ZTE Open review a rough start for Firefox OS

More Info

We should reiterate what we said earlier in the review: the ZTE Open is partly intended as a developer phone. For those customers, it does the job well. You don't need a quad-core processor or a 1080p display to demonstrate that your HTML5 app runs properly. For $80 unlocked, the smartphone is even something of a bargain; it's cheap enough that you could buy several for a programming team. If you're looking for a testbed device, don't hesitate to pick one up.

There are also certain everyday customers who might like the Open. If you're just considering a smartphone for the first time and object to the complexity or cost of what's on the market, it's hard to beat the pricing. On Movistar Spain, the Open costs €58 ($78) with prepaid service; the Optimus L3 II is twice as expensive, at €116 ($156). Travel to Colombia and the 149,900 pesos (also $78) that you'll pay at Movistar will easily undercut a phone like Samsung's Galaxy Young, which costs 317,900 pesos ($167). Mozilla argues that Firefox OS brings smartphones to a wider audience, and it's right -- some customers would be relegated to a basic feature phone if the Open weren't available.

For many of you reading this, the Open won't make sense. The price differences between the Open and more advanced devices either won't matter as much, or aren't that large to start with. Americans will want to look at the Nokia Lumia 620 from Aio Wireless -- it's only slightly more expensive at $100 prepaid, but much more powerful. If you can spend $30 more beyond that, you may also want to consider a few Samsung phones, such as the Galaxy Amp (at Aio Wireless) and Galaxy Reverb (at Virgin Mobile). It's a tougher call if you're in Spain or another market where these deals aren't available, but we would investigate phones like the Optimus L3 II or Sony Xperia E. The Open is fine as a child's first phone or a backup device, however.

Whether or not the Open fits your needs, one thing is clear: Mozilla needs more capable hardware to demonstrate Firefox OS' potential. The Open is good for someone whose alternative would be a basic flip phone, but the camera quality, connectivity, display and performance don't do full justice to the software. Thankfully, more smartphones are coming. Along with a more powerful ZTE phone, we can also expect the (unsanctioned) Geeksphone Peak+. The as-yet-unannounced devices from Huawei and LG may also be worth waiting for. Firefox OS could easily take off -- it just needs a better launch vehicle.