True hinge-angle support
Reads Sensor.TYPE_HINGE_ANGLE continuously where the device exposes one, and falls back gracefully to Android's fold-state API where it doesn't — so the effect works across foldable lineups.
For Android foldables · Android 12+
The fold,
The fold,
made fluid.
FoldFX recreates the fluid, hinge-driven screen transition your foldable deserves. Instead of hard-cutting between cover and main layouts, your interface visibly blurs, scales and reshapes itself as the phone physically opens — tracking the real speed of your hand.
- Real hinge sensorwith graceful fallback
- Angle-drivenno canned animation
- Private by designno data collected
Interactive preview
Drag the hinge. Watch it fold.
This is a live web replica of FoldFX's core transition — the same angle-driven blend, with a gradient blur that blooms out of the hinge, a motion smear that tracks the speed of your hand, and a diagonal light sweep. Fold slowly and it eases through slowly; flick it open and it smears through fast.
0°
Closed · cover screen
Tip: you can also grab the phone itself and drag it open.
A live 3D simulation of a book-style foldable running the FoldFX transition: the cover display hands off to the main display through a hinge-weighted gradient blur, a velocity-driven motion smear and a light sweep, all driven by the fold angle. On device, that angle comes from the real hinge sensor; the slider mirrors the debug tool built into the app.
Straight from the app
The real thing
Real screens captured from FoldFX running on a device — the live-telemetry home and the transition viewport with its manual angle override — alongside the launch marketing render. Tap any image to view it full size.
Features
Everything a fold transition should be
FoldFX is built around a single, continuous value — the fold angle — and layers physical effects on top of it, so the result feels like glass moving with your hand rather than two screens being swapped.
Continuous blending
The cover and main layouts don't snap at a fixed threshold. A single angle value continuously blends between the compact single-column layout and the expanded grid, in both directions.
Physical mid-fold effects
A gradient blur that blooms out of the hinge and peaks partway through the fold, a motion smear that follows the speed of your hand, a slight scale-up and a soft diagonal light sweep ride along mid-transition, so it reads as glassy and physical — never like a hard cut.
Tracks your hand
Because the animation is driven directly by the sensor, it follows the actual speed of your gesture. Fold slowly and it eases through slowly; flick it open and it snaps through fast.
Haptic midpoint tick
A single, subtle haptic tick fires at the transition's midpoint — once per gesture — giving the fold a satisfying tactile "click" right as the interface changes sides.
Tunable & persistent
Adjust the reveal window (which angles trigger the transition) and the blur strength to taste. Settings persist across restarts via DataStore preferences, and an on-screen debug slider lets you tune without folding.
Under the hinge
One angle value. Everything follows.
The whole effect is a pipeline from hardware to pixels, rebuilt from scratch in Kotlin — an original implementation of the idea, not a port of anyone's code or assets.
-
01
Sense
Jetpack WindowManager watches fold state, while
Sensor.TYPE_HINGE_ANGLEstreams the physical hinge angle in real time as the phone opens and closes. -
02
Blend
The raw angle is mapped through the adjustable reveal window and used to continuously cross-blend a compact cover layout into the expanded main layout — no fixed cut-off point.
-
03
Effects
A hinge-weighted gradient blur peaks mid-fold, content compresses gently into the crease, and a soft diagonal light sweep glides across — all weighted by a sine curve so the middle of the fold feels the most cinematic.
-
04
Feel
A single haptic tick marks the midpoint — once per gesture — while DataStore keeps your reveal window and blur strength exactly where you left them.
Honest by design
What FoldFX is — and what it isn't
No marketing fog. Here's exactly where the effect lives and what it can and cannot touch on your device.
✓ What it is
- A from-scratch Android implementation of the fluid, hinge-driven fold transition that wowed everyone when flagship book-style foldables arrived in September 2026
- A live, sensor-driven demo of the technique: blending two layouts using one continuous angle value
- An homage built with original code, original names and original assets — a generic animation approach, not anyone's proprietary design
- A base that can grow into a live wallpaper or custom home-screen launcher in later phases
✕ What it isn't
- Not a system-level replacement — it can't change how other apps transition when you fold; that's a privilege the operating system reserves for itself on stock Android
- Not affiliated with, endorsed by, or derived from any device manufacturer in any way
- Not a canned GIF-style animation — the motion is generated live from your hinge sensor
- Not a data collector — it needs no account and phones nothing home
Tech stack
Modern Android, end to end
Built with the current generation of Android tooling, targeting the newest foldable APIs while staying compatible with devices running Android 12 and later.
Language & UI
KotlinJetpack ComposeMaterial 3
Foldable APIs
androidx.windowSensor.TYPE_HINGE_ANGLEFold-state fallback
Persistence
DataStore PreferencesPersistent settings
Requirements
Android 12+Foldable device recommendedVersion 1.0
FAQ
Questions, answered
Will FoldFX change how every app animates when I fold my phone?
No — and no third-party app can. Modifying system-wide transitions is an OS/OEM-level privilege on stock Android. FoldFX brings the effect to its own interface, to your live wallpaper, and — experimentally, behind a clear disclosure screen — to other apps' screens via an accessibility overlay.
Does my phone need a hinge-angle sensor?
It helps, but it isn't required. On devices that expose Sensor.TYPE_HINGE_ANGLE, FoldFX uses the real continuous angle. Where the sensor isn't available, it falls back to an approximation derived from Android's fold-state API, so the transition still works — just with fewer intermediate steps.
Which devices are supported?
FoldFX runs on Android 8.0 (API 26) or newer and is designed for foldable phones — book-style and flip-style. The highest-quality render path needs Android 12+; older versions automatically use a compatible path. On non-foldable devices you can still experience and tune the full effect with the built-in on-screen slider. FoldFX is still in beta, though, and might have issues on some devices — hinge response, wallpaper and overlay rendering vary across foldable models and OEM Android builds. If something misbehaves on yours, report it and it will shape the next build.
What can I customize?
The "reveal window" — which range of angles drives the transition — and the blur strength are both adjustable in-app and saved persistently. The on-screen debug slider lets you rehearse the effect without physically folding the phone.
Is FoldFX affiliated with any device maker?
No. FoldFX is an independent homage to a UI technique. It's built with original Kotlin code, original names and original assets — the underlying idea of blending two layouts with a live angle value is a generic animation approach, not proprietary technology. FoldFX is not endorsed by or affiliated with any device manufacturer or platform vendor.
Does it collect my data?
No. Hinge angles and settings are processed and stored entirely on your device. FoldFX has no accounts, no analytics and no ads. See the Privacy Policy for the full detail.
What's new
Version 0.2.6 · Smooth on every foldable
- The fold now glides — on some phones it used to jump in steps; now it flows like a real hinge on every foldable we support.
- FoldFX no longer depends on your phone’s mood — it fills in what the phone can’t tell it, so the fold always looks smooth and natural.
- If your phone stops sharing fold information, the effect keeps flowing instead of freezing in place.
- Every open and close settles in gently — a softer start, a graceful finish.
0.2.5
0.2.6
Smoothness
On some phones the fold jumped in steps
Glides like a real hinge on every foldable
Adaptability
Needed the phone to share every fold detail
Lovely even when the phone can’t share details
Keeps going
Could freeze if the phone stopped responding
Keeps flowing no matter what the phone does
The fold, in your hands.
Buy once, download straight from here, keep it forever — no store, no subscription.
One-time payment · key moves between devices anytime · hassle-free refunds via Polar
Secure checkout by Polar
- On-device only
- No account needed
- No ads
- Works offline
Version 0.2.6 · Android 8.0+ · Beta software — behavior varies by device