TwinLens is a free, browser-based image comparison tool with a minimalist design that uses your full screen for comparison — no sidebars, no clutter, nothing to install. This guide walks you through every step, from loading your first image to sharing a permanent link with a colleague.
Step 1 — Open the tool
No account, no install, no email required. The tool runs entirely in your browser. Your images never leave your device — everything is processed locally.
The interface is intentionally minimal: two empty image panels fill your entire screen, ready to receive your images.
Step 2 — Load your images
You have two ways to load images:
- Drag and drop: drag an image file from Finder or Explorer and drop it onto the left or right panel.
- Click to browse: click anywhere on an empty panel to open a file picker.
Supported formats include JPG, PNG, WebP, AVIF, HEIC, GIF, and BMP. You can load up to four images and switch between side-by-side, horizontal, and grid layouts.
Step 3 — Choose a view mode
Use the mode buttons in the toolbar to switch between views:
| Mode | How it works | Best for |
|---|---|---|
| Slider | Drag a vertical divider left or right to reveal one image over the other | Before & after retouching, UI revisions |
| Split | Both images sit side by side with a fixed divider | Color grading, layout comparisons |
| Peek | Click and hold to see the second image; release to snap back | Spot-checking subtle differences quickly |
| Diff | Highlights pixel-level differences in red and shows a similarity score | QA, design reviews, version diffing |
Step 4 — Zoom in and inspect details
Scroll anywhere in the comparison area to zoom in. Both panels zoom and pan in sync, so you always inspect the same region of both images at the same time.
- Drag to pan after zooming in.
- Press F to fit both images to the window.
- Press 1 to jump to 100% (1:1 pixel view) for maximum detail.
- Double-click to reset zoom.
Step 4b — Label and annotate
Click the label area beneath each image to type a custom name — for example Before Retouch and After Retouch. Labels appear on the comparison view and are included in exported snapshots.
In Slider mode the labels float at the bottom-left and bottom-right of the panel so they stay visible regardless of slider position.
Step 5 — Export or share
Export a snapshot
Click the Snapshot button (camera icon) in the toolbar to download the current comparison view as a PNG. The exported image includes both panels, the divider, and any labels you have set. Press P for a keyboard shortcut.
Generate a shareable link
Click the Share button (link icon) to upload your images and generate a permanent shareable URL. Anyone with the link can view your comparison — they do not need a TwinLens account or install.
- Images are stored securely and linked to the share ID only.
- The link opens directly in the same view mode you had active.
- Copy the URL from the dialog and paste it into Slack, email, or a design review thread.
Keyboard shortcuts reference
TwinLens is designed for keyboard-first workflows. Here are the most useful shortcuts:
| Key | Action |
|---|---|
| S | Toggle Slider / Split view |
| F | Fit to window |
| 1 | 100% zoom (actual size) |
| P | Save snapshot to PNG |
| X | Swap left and right images |
| ? | Show all shortcuts |
Common use cases
- Photo retouching: load the original RAW export and the edited JPEG to review every adjustment.
- UI design reviews: compare the mockup PNG with a browser screenshot to catch spacing and color drift.
- Before & after: real estate photos, product shots, landscape photography — drag the slider to create a dramatic reveal.
- QA & regression testing: use Diff mode to spot pixel-level regressions between two builds of a rendered UI.
- Print prepress: check that the CMYK PDF export matches the RGB screen proof at 100% zoom.
Ready to compare?
Free, private, and instant. No account or install needed — just open the tool and drop your images in.
Compare Images Now — No Install Needed →