TrailStack vs FormSync

Turn any video into a stunning strobe photo — right on your iPhone device. TrailStack stacks multiple frames from your video into one composite image, creating the classic strobe effect used by sports photographers, coaches, and creative artists. No cloud upload. No subscription. No Photoshop skills required. HOW IT WORKS 1. Pick any video from your camera roll 2. Adjust Trim, Interval, Sensitivity, Fade, and Cleanup sliders 3. See results instantly in the real-time preview 4. Export a crisp PNG at your video's original resolution to your Photos KEY FEATURES • Import any existing video — no in-app recording required • Real-time preview as you adjust every parameter • 4 built-in presets: Default, Sport, Art, Sharp • Supports slow-motion video for ultra-detailed motion analysis • Export at original video resolution PNG (up to 1920px on the longest side) • 100% on-device processing — your videos never leave your phone • Free to use, with an optional ad to remove the watermark from exports PERFECT FOR • Athletes & coaches — analyze a golf swing, tennis serve, or gymnastics routine • Skateboarders & BMX riders — capture trick sequences in one frame • Dancers & performers — visualize choreography and movement flow • Physics & science teachers — demonstrate motion and velocity visually • Social media creators — create eye-catching composite sports photos WHY TRAILSTACK? Other strobe photo apps require you to record video inside the app — TrailStack works with footage you already have. Sony MotionShot was discontinued in 2021. Clipstro is iOS-only and cannot import existing videos. Photoshop can achieve similar results, but takes 30–60 minutes of manual work per photo. TrailStack does it in seconds. PRIVACY FIRST All processing happens entirely on your device. We never upload, store, or transmit your photos or videos to any server. What's on your phone stays on your phone. FREE & FAIR TrailStack is free to download and use. Exports include a small watermark. Watch a short optional ad to save a watermark-free version at any time — no subscription, no hidden fees. Download TrailStack and see your movement in a whole new way.

FormSync lets you place two videos side by side and play them together — a simple app for checking form. Compare any kind of movement: dance, golf, tennis, baseball, training, and more. Put a reference next to yourself, or your past form next to today's, and spot the differences at a glance. Features - Pick two videos from your camera roll and view them side by side - Play and pause both videos at the same time - A shared seek bar to move both to the same position - Slow-motion playback (0.25x / 0.5x / 0.75x / 1x) - Set a start point for each video and fine-tune it in 0.05s steps - Jump to start / skip forward 10s / back 10s - Pinch to zoom in and check the fine details up close (zoom is kept in your exports too) - Landscape mode on the compare screen - Swap one video and keep the other — compare new takes against your reference, one after another - Mirror view — flip either video horizontally to match your reference's direction - Draw straight lines to compare form — angle and alignment (PRO) - Auto-detect pose — full-body skeleton and spine angle drawn in one tap (PRO) - Export your comparison as a single video, landscape or vertical 9:16 (saved to your camera roll, ready to share) - Set an end point and export just the range you want to show - Save your comparisons to history, name them, and revisit them Free - Compare any videos — preview plays 10 seconds from your chosen start points - Export comparisons up to 10 seconds (with a small watermark) - Keep your 5 most recent comparisons in history PRO (one-time purchase) - Play and compare videos in full length - Draw straight lines to compare form — angle and alignment, baked into your exports too - Auto-detect pose — full-body skeleton plus spine angle for your golf swing, in one tap - Export full-length comparisons (watermark can be turned off) - Keep unlimited history All videos are processed on your device and are never uploaded to a server. For iPhone.