FOSSiBOT S3 Pro Review: The $139 Phone That Feels Like a Flagship Killer!

I want to talk about the FOSSiBOT S3 Pro because this phone is honestly one of the most surprising budget devices I’ve seen in a long time. Imagine getting a phone with a 2K AMOLED curved display, a secondary rear screen, and a 5000mAh battery—all for just $139. Sounds too good to be true, right? Well, that’s exactly what FOSSiBOT is offering here, and it’s making a lot of noise in the budget smartphone market.

Now, I know what you’re thinking—how can a phone this cheap have features that even some mid-range devices don’t offer? That’s exactly what I wanted to find out. The FOSSiBOT S3 Pro is not just another budget phone; it’s trying to redefine what we expect from devices in this price range. From its sleek design to its impressive display and unique rear screen, this phone is packed with features that make it stand out. But does it actually deliver where it matters? Spoiler alert: it might just blow your mind.

Design and Build Quality

For a device that costs just $139, the FOSSiBOT S3 Pro doesn’t feel cheap at all. In fact, it’s one of those phones that makes you double-check the price tag because it looks and feels way more premium than it has any right to. The phone has a metal frame, which is a big deal at this price point. Most budget phones go for plastic frames to cut costs. It’s the kind of thing that makes you feel like you’re holding something more expensive. On the back, you’ve got a plastic panel, but don’t let that fool you—it’s not the cheap, glossy plastic that attracts fingerprints like crazy. Instead, it has a matte-like finish that feels smooth to the touch and does a great job of hiding smudges. Plus, it’s practical because, let’s be honest, glass backs are fragile, and no one wants to deal with a cracked phone.

Now, let’s talk about the ergonomics. The S3 Pro is 8.65mm thick and weighs 199 grams, which is pretty standard for a phone with a large display and a big battery. But here’s the thing—it doesn’t feel bulky or heavy in the hand. The curved edges on both the front and back make it super comfortable to hold, and the phone sits nicely in your palm. It’s one of those devices that you can use one-handed without feeling like you’re going to drop it every five seconds.

On the right side, you’ve got the power button and volume rocker, both of which are easy to reach and have a nice, clicky feel to them. The buttons don’t wobble or feel loose, which is another sign of good build quality. On the bottom, there’s a USB-C port, a microphone, and a speaker grille. The SIM tray is also down here, and it supports either dual SIM cards or one SIM card plus a microSD card for expandable storage (up to 1TB, which is awesome).

The front of the phone is where things get really interesting. You’ve got a 6.67-inch curved AMOLED display that dominates the front panel. The bezels are thin, especially on the sides, and the screen curves gently into the frame, giving it that premium look you’d expect from much more expensive phones. The chin at the bottom is slightly thicker, but it’s not distracting, and honestly, at this price, it’s more than acceptable.

Now, let’s not forget the star of the show—the secondary rear display. On the back, there’s a circular module that houses the cameras and a 1.09-inch touch-sensitive screen. This little display is functional and adds a cool factor to the phone. You can use it to check notifications, control music, see the time, or even take selfies using the rear camera. It’s not something you’ll use all the time, but it’s a neat feature that sets the S3 Pro apart from other budget phones.

Display Quality

In fact, the display is one of the main reasons this phone is turning heads in the budget smartphone market. The main display is a 6.67-inch 2K AMOLED panel. Yes, you read that right—2K AMOLED on a $139 phone. This is the kind of display you’d typically find on much more expensive devices, so seeing it here is a real treat. The resolution is 2400 x 1080 pixels, which translates to a sharp 394 pixels per inch (PPI). What does that mean in real-world use? Everything looks crisp, clear, and detailed.

Now, let’s talk about the AMOLED technology. If you’re not familiar, AMOLED displays are known for their vibrant colors, deep blacks, and excellent contrast. Each pixel on an AMOLED screen emits its own light, which means you get true blacks because the pixels can turn off completely. This makes colors pop and gives the screen a more dynamic and immersive feel. Watching movies or playing games on this display is a joy because the colors are so rich and lifelike.

The curved edges of the display add to the premium feel of the phone. It’s not just for looks—the curves make the phone more comfortable to hold and give it a sleek, modern aesthetic. The screen-to-body ratio is 96.6%, which means there’s very little bezel around the display. This makes the phone feel more immersive, especially when you’re watching videos or playing games.

Brightness is another area where the S3 Pro excels. The display can hit up to 1800 nits in High Brightness Mode (HBM), which is fantastic for outdoor use. Even in direct sunlight, you’ll have no trouble seeing what’s on the screen. Indoors, the display is equally impressive, with excellent viewing angles and consistent color accuracy no matter how you tilt the phone.

The always-on display (AOD) feature is also worth mentioning. It allows you to see the time, date, and notifications without waking up the phone. This is super convenient and helps save battery life since you don’t have to turn on the main display just to check the time.

Now, let’s not forget the secondary rear display. This is a 1.09-inch circular touch-sensitive screen located on the back of the phone, right in the camera module. It’s a unique feature that adds a lot of functionality. You can use it to check notifications, control music, see the time, or even take selfies using the rear camera. It’s not something you’ll use all the time, but it’s a neat addition that sets the S3 Pro apart from other budget phones.

Finally, the under-display fingerprint sensor is fast and reliable. It’s conveniently located and works well in most conditions. It’s not the fastest sensor out there, but it’s more than adequate for everyday use.

Performance and Benchmarks

When you’re dealing with a budget phone, you might expect some compromises, but the FOSSiBOT S3 Pro manages to hold its own surprisingly well. This phone is powered by the MediaTek Helio G85 processor. Now, this isn’t the most powerful chipset out there, but it’s a solid choice for a budget phone. It’s built on a 12nm process and features an octa-core setup: two Cortex-A75 cores clocked at 2.0 GHz for heavy lifting and six Cortex-A55 cores at 1.8 GHz for lighter tasks. This combination is designed to balance performance and power efficiency, which is exactly what you want in a budget device.

The phone comes with 6GB of RAM, which is pretty decent for the price. But here’s the kicker—FOSSiBOT includes a memory expansion feature that lets you virtually extend the RAM up to 20GB by using part of the internal storage. Now, before you get too excited, this isn’t the same as having actual physical RAM, but it does help with multitasking and keeping apps running smoothly in the background.

For storage, you get 128GB of internal space, which is more than enough for most users. If you need more, there’s a microSD card slot that supports cards up to 1TB, so you’ll never run out of space for your photos, videos, and apps.

In everyday use, the FOSSiBOT S3 Pro handles itself pretty well. Apps open quickly, and switching between them is smooth thanks to the 6GB of RAM. Social media apps like Instagram, Facebook, and Twitter run without a hitch, and even more demanding apps like YouTube and Spotify work flawlessly. Scrolling through feeds, watching videos, and browsing the web are all smooth experiences.

Multitasking is also a breeze. You can have multiple apps open at once, and the phone doesn’t struggle to keep up. The memory expansion feature helps here, allowing you to keep more apps in the background without them reloading every time you switch back.

Gaming Performance

Now, let’s talk gaming. The Mali-G52 GPU inside the Helio G85 is capable of handling casual games like Candy Crush, Subway Surfers, and Among Us without breaking a sweat. These games run smoothly, and the AMOLED display makes everything look vibrant and immersive.

However, when it comes to more demanding games like Call of Duty Mobile or Genshin Impact, you’ll need to dial down the graphics settings to get a playable frame rate. At medium settings, these games are playable, but don’t expect buttery-smooth performance at high settings. The phone can handle light to moderate gaming, but it’s not a gaming powerhouse. That said, for casual gamers, it’s more than sufficient.

Benchmark Results

Let’s get into some numbers. I ran a few benchmarks to see how the FOSSiBOT S3 Pro stacks up against other budget devices.

• AnTuTu Benchmark: The phone scored around 236,000 points, which is decent for its price range. It’s not going to blow anyone away, but it’s more than enough for everyday tasks and light gaming.
• Geekbench 5: In single-core performance, the S3 Pro scored 442 points, and in multi-core, it managed 1,407 points. Again, these scores are solid for a budget device and show that the phone can handle most tasks without issue.

Camera Performance

Cameras are always a big deal, especially in budget phones, because this is where manufacturers often cut corners. But FOSSiBOT seems to have put some effort into the camera system here, so let’s see if it delivers.

The FOSSiBOT S3 Pro has a triple-camera setup on the back:

• 64MP Main Camera: This is the star of the show, using a Sony IMX682 sensor. It’s the primary camera for most of your shots.
• 2MP Macro Camera: For close-up shots, though it’s more of a “nice to have” than a must-have.
• Depth Sensor: Helps with portrait mode and adding that bokeh effect to your photos.

On the front, there’s an 8MP selfie camera tucked into a small punch-hole cutout. It’s not the most impressive spec on paper, but let’s see how it performs in real life.

Daylight Photography

In good lighting conditions, the 64MP main camera actually does a pretty decent job. Photos come out with good detail, vibrant colors, and decent dynamic range. If you’re shooting landscapes or well-lit scenes, you’ll be happy with the results. The AI photography mode kicks in to optimize scenes, and it works well for things like greenery, skies, and food.

That said, the 64MP mode is more of a gimmick. Sure, it captures more detail, but the file sizes are huge, and the difference isn’t always noticeable unless you’re zooming in a lot. For everyday use, the standard 16MP shots (pixel-binned from 64MP) are more than enough.

The 2MP macro camera is… well, it’s there. It’s not great, but it’s fun to play around with if you’re into close-up shots. Just don’t expect professional-level detail—it’s more of a novelty feature.

Low-Light Photography

This is where the S3 Pro starts to show its budget roots. In low-light conditions, the main camera struggles a bit. Photos can come out grainy or noisy, and details get lost in darker areas. The Night Mode helps a little by brightening up the scene and reducing noise, but it’s not magic. You’ll get usable shots, but don’t expect flagship-level low-light performance.

Portrait Mode

Portrait mode is where the depth sensor comes into play. The S3 Pro does a decent job of separating the subject from the background, and the bokeh effect looks natural in most cases. Edge detection isn’t perfect, especially with complex backgrounds or hair, but for a $139 phone, it’s pretty impressive. The AI also helps adjust skin tones and lighting, so your portraits look polished without too much editing.

Selfies

The 8MP front camera is… fine. It gets the job done for video calls and casual selfies, but don’t expect anything groundbreaking. In good lighting, selfies look decent with natural skin tones and enough detail. In low light, though, things get muddy, and the lack of a front-facing flash or night mode doesn’t help. The AI beauty mode is there if you want to smooth out your skin, but it can look a bit artificial if you crank it up too high.

Here’s a fun feature: the 1.09-inch circular display on the back lets you use the 64MP main camera for selfies. This is great because the rear camera is way better than the front one. You can frame your shots using the small screen, and the results are noticeably sharper and more detailed than regular selfies. It’s a bit gimmicky, but it works well if you’re into taking high-quality selfies.

Video Recording

The FOSSiBOT S3 Pro can record video at 1080p and 30fps. The quality is okay for a budget phone—colors are accurate, and the footage is stable thanks to electronic stabilization. However, there’s no 4K recording, which is a bit of a bummer but understandable at this price point.

The stabilization works well for walking shots or casual vlogging, but don’t expect it to handle fast movements or shaky hands perfectly. The audio quality is decent, but the microphone can pick up wind noise if you’re outdoors.

Software Experience

After all, a phone can have all the hardware in the world, but if the software isn’t smooth and user-friendly, it can ruin the whole experience. The FOSSiBOT S3 Pro runs on Android 14 out of the box, which is a big win for a budget phone. Android 14 brings all the latest features, improvements in privacy, and better performance optimizations. It’s great to see a budget device launching with the latest Android version, especially when some mid-range phones are still stuck on older versions.

FOSSiBOT has added its own custom skin on top of Android, but thankfully, it’s not overly bloated. The interface is clean, simple, and easy to navigate. It’s not as heavy as some other custom skins (looking at you, MIUI), which means it doesn’t slow down the phone or eat up too much RAM.

The home screen is straightforward, with an app drawer that keeps things organized. You can customize the home screen with widgets, change icon styles, and even tweak the animation speeds if you want a snappier feel. The notification shade is clean, with quick toggles for things like Wi-Fi, Bluetooth, and NFC. There’s also a dark mode, which looks great on the AMOLED display and helps save battery life.

Pre-Installed Apps

One of the best things about the S3 Pro’s software is that it doesn’t come loaded with a ton of bloatware. Sure, there are a few pre-installed apps, but most of them are useful, like a file manager, calculator, and FM radio. There’s no annoying third-party junk that you’ll need to uninstall right away, which is a breath of fresh air for a budget phone.

Gestures and Navigation

The S3 Pro supports gesture-based navigation, which is my personal favorite way to use Android. Swiping up to go home, swiping from the sides to go back—it all feels intuitive and smooth. If you prefer the old-school three-button navigation, that’s an option too.

There’s also a Smart Touch feature that lets you customize gestures for quick actions. For example, you can double-tap the screen to wake it up or swipe in a specific direction to launch an app. It’s a small but handy addition that makes the phone feel more personalized.

Bugs and Quirks

No software is perfect, and the S3 Pro does have a few minor quirks. For example, I noticed that the secondary rear display can sometimes be a bit slow to respond, especially when switching between functions like the music player and notifications. It’s not a dealbreaker, but it’s something to keep in mind.

There’s also the occasional animation stutter, especially when switching between heavy apps. It’s not frequent, but it does happen. That said, these issues are minor and don’t take away from the overall smoothness of the experience.

Battery Life and Charging

Now, let’s talk about one of the most important aspects of any smartphone—battery life. After all, what good is a phone with a great display and smooth performance if it dies halfway through the day? The FOSSiBOT S3 Pro packs a 5,000mAh battery, which sounds promising, but let’s see how it holds up in real-world use.

The 5,000mAh battery in the S3 Pro is a beast. In my testing, the phone easily lasted a full day of moderate to heavy use. Here’s a breakdown of what I got:

• Social Media and Browsing: Scrolling through Instagram, Twitter, and Facebook for a couple of hours used about 15-20% of the battery. Not bad at all.
• Streaming Videos: Watching YouTube or Netflix for an hour drained around 8-10%. The AMOLED display helps here since it’s more power-efficient when showing darker content.
• Gaming: Playing casual games like Candy Crush or Among Us for an hour used about 12-15%. More demanding games like Call of Duty Mobile pushed that closer to 20%, but that’s expected.
• Standby Time: The phone sips power when idle, losing only 1-2% overnight. This is thanks to Android 14’s optimizations and the efficient Helio G85 chipset.

If you’re a light user, you can easily stretch the battery to two days. But even with heavy use—streaming, gaming, and multitasking—the S3 Pro will get you through a full day without breaking a sweat. For a $139 phone, this kind of battery life is seriously impressive.

Now, let’s talk about the 18W fast charging. While it’s not as blazing fast, it’s still a solid feature for a budget phone. The included 18W charger gets the job done at a reasonable pace. Here’s how fast it charges:

• 0 to 50%: In about 45 minutes. That’s enough to get you through most of the day.
• 0 to 100%: In roughly 1 hour and 45 minutes. It’s not the fastest charging out there, but it’s still decent for a phone in this price range.

If you’re someone who charges their phone overnight or during downtime, the 18W charging is perfectly fine. It’s not going to blow your mind, but it’s reliable and gets the job done.

 Pros and Cons

Final Verdict

Finally, let’s wrap this up. The FOSSiBOT S3 Pro is one of those rare budget phones that feels like it shouldn’t exist at its price point. For just $139, you’re getting a phone with a stunning 2K AMOLED display, a unique secondary rear screen, and a 5,000mAh battery that lasts all day. Add in decent performance, a clean software experience, and a surprisingly good main camera, and you’ve got a device that’s hard to beat.

You can purchase it directly from the official FOSSiBOT website or through authorized retailers like AliExpress. During the launch period (January 20th to February 7th), the phone is available at the discounted price of $139 with a coupon code. After that, the price may go up to its original $270, so if you’re interested, now’s the time to grab it.

If you’re in the market for a budget phone and can snag the S3 Pro for $139, don’t hesitate—it’s one of the best values you’ll find in 2025. Even at its original price of $270, it’s still a solid choice, but at the discounted launch price, it’s an absolute steal.

So, what are you waiting for? Head over to the FOSSiBOT Store and get yourself this incredible budget phone before the deal ends. You won’t regret it!

And that’s a wrap on the FOSSiBOT S3 Pro! Let me know if you have any questions or if there’s anything else you’d like to know about this impressive little device. 😊