Long Screenshot Merger
Long Screenshot Merger
Stitch scrolling screenshots into one long image with overlap removal and overlap fine-tuning.
Drag and drop images here or click to browse
Supports PNG / JPEG / WebP / AVIF / HEIC / HEIF
🚀 Quick Start
- Upload multiple scrolling screenshots
- Choose Vertical or Horizontal
- Keep Auto dedupe on; tweak Advanced settings or disable it if detection is unstable
- If the order is wrong, drag to reorder (or sort by name/time from the Sort menu in the bottom toolbar).
- Fine-tune seams/crops in Preview first (use ↺ to restore if needed), then open Overlaps to fix low-confidence boundaries, and download
🧩 Preview Fine-tuning
- In Preview, click the button on a seam to unlock (shows ✓). The view will auto-focus on that seam when needed; left-drag either image around the seam to fine-tune alignment (the seam line stays fixed). Right-drag pans the view; mouse wheel zooms.
- When ↺ appears on a seam, click it to restore that seam’s adjustments.
- For Top/Bottom (or Left/Right), unlock the edge button and drag near the edge in a large area to adjust cropping; the buttons follow the edge.
- When ↺ appears on the edge, click it to restore cropping to 0.
📌 Common Scenarios
- Stitch scrolling web page screenshots (articles/docs/etc.)
- Merge chat log screenshots (WhatsApp/Telegram/etc.)
- Combine comics or long images in parts (needs stable overlap)
- Join horizontal scrolling/panorama segments (Horizontal mode)
🎛️ Dedupe & Overlap Settings
- Direction: Vertical/Horizontal stitching.
- Auto dedupe: detects overlap between adjacent screenshots and removes duplicates.
- Overlaps panel: manually enter overlap pixels per boundary (used for dedupe cropping); clear to return to auto. Works best together with Preview fine-tuning.
- Max/Min overlap: narrows the search range to reduce false positives.
- Tolerance / Scan step: higher tolerance is more forgiving; smaller step is more accurate but slower.
- Diff / Confidence: lower diff and higher confidence means more reliable; review low-confidence boundaries.
- Smart sort (experimental): tries to infer order automatically; may be unreliable with many/similar images.
🧭 Usage Advice
- Keep ~10–30% overlap between screenshots and avoid large dynamic regions (video/animations/infinite scroll).
- If detection is unstable, fix the order first (drag, sort by time, reverse). Correct order usually matters more than tweaking.
- Tune one parameter at a time: start with max/min overlap, then adjust tolerance/step for fine-tuning.
- For low-confidence boundaries, manually set overlaps or temporarily disable auto dedupe before exporting.
- If the output is very large, set a max export size to reduce memory usage and export failures.
⚠️ Limitations & Compatibility
- Requires stable overlap between adjacent screenshots; with no overlap or huge content differences, auto dedupe won't work.
- Dynamic content can confuse detection and cause duplicates/missing parts.
- Many/high-res screenshots can be memory-heavy and slow; try batching or resizing first.
- Use the latest Chrome/Edge/Firefox or Safari 16+ (HEIC/HEIF support varies by browser).
🔒 Privacy & Security
- All processing happens in your browser; data never leaves your device
❓ FAQ
Why does the output have duplicates or missing parts?
Check the order first. Then review low-confidence boundaries in Overlaps: manually set overlap pixels, tweak advanced settings, or disable auto dedupe before exporting. Too little overlap or too much dynamic content can also cause mis-detection.
What do “Diff/Confidence” mean?
Diff measures similarity around a boundary (lower is more similar). Confidence is an estimate of reliability. Low confidence usually means you should review or tweak settings.
When does Smart sort fail?
With many files, highly similar content (solid colors/repeated layouts), or screenshots from different pages, the inferred order can be unstable—manual ordering is recommended.
Why does export ask for confirmation?
To prevent obvious duplicates/missing parts when low-confidence boundaries exist. Fix overlaps or disable auto dedupe, then choose “Export anyway” if needed.