Image Stacker & Overlay
Upload a base image and an overlay image, then configure blend mode, opacity, scale, and position to create a merged composite. Choose from 16 blend modes — the same ones used in Photoshop. All processing runs locally in your browser. No signup required.
Base Image (background)
Overlay Image (top layer)
Overlay Controls
Controls how the overlay pixels blend with the base image pixels.
PNG is always lossless.
Why Use Our Image Stacker & Overlay Tool?
Instant Image Overlay
Merge two images in seconds. Our image stacker processes everything locally in your browser using the Canvas API — no upload wait, no server queue, instant before/after preview.
Secure Image Stacker Online
Your images never leave your device when you overlay and stack images. 100% client-side processing guarantees complete privacy — no cloud storage, no logs, no data collection.
Image Overlay Online — No Installation
Stack and overlay images online directly in your browser. No software downloads, no plugins, no account required to use this free image stacker and overlay tool.
100% Free Forever
Use this image stacker and overlay tool without signup, subscriptions, rate limits, or hidden paywalls. Overlay as many images as you need, completely free, with no ads.
Common Use Cases for Image Stacker & Overlay
Social Media Composites
Overlay logos, watermarks, or decorative elements onto photos for Instagram, Facebook, and Pinterest posts. Use the image stacker to create consistent branded visuals across your social channels.
Double Exposure Effects
Create stunning double exposure photography by stacking two images with Screen or Multiply blend modes. The image overlay tool gives you full control over opacity and blend mode for artistic results.
Watermark & Branding
Add logo watermarks to product photos, portfolio images, or marketing assets. Position the overlay precisely using alignment controls and adjust opacity to keep the watermark subtle.
Texture & Pattern Overlays
Apply texture images (grunge, paper, bokeh) over photos using blend modes like Overlay or Soft Light. The image stacker lets you scale and position the texture for perfect coverage.
UI Mockup Compositing
Designers can overlay app screenshots onto device mockup frames, or combine UI elements with background images. The image overlay tool supports PNG transparency for clean compositing.
Photo Manipulation & Art
Combine portraits with landscape backgrounds, merge abstract art layers, or create surreal composites. All 16 CSS blend modes are available for creative image stacking effects.
Understanding Image Stacking & Overlay
What is Image Stacking & Overlay?
Image stacking and overlayis the process of compositing two or more images on top of each other to create a merged result. Our image stacker uses the browser's Canvas 2D API and its globalCompositeOperation property to apply one of 16 standard blend modes — the same modes used in Photoshop and CSS. The base image forms the background layer, and the overlay image is drawn on top with configurable opacity, scale, and position. All image stacking and overlay processing happens entirely in your browser — your images never leave your device.
How Our Image Stacker & Overlay Tool Works
- 1Upload your two images: Drop or click to upload a base image (the background) and an overlay image (the top layer). Both support JPEG, PNG, WebP, GIF, and BMP formats.
- 2Configure the overlay controls: Choose a blend mode, set opacity (0–100%), scale the overlay (5–200%), and position it using alignment presets (top/center/bottom, left/center/right) or custom X/Y pixel offsets.
- 3Apply and download: Click "Apply Overlay" to composite the images and see the before/after preview. Choose PNG, JPG, or WebP output and click "Download Result" to save.
What the Blend Modes Do
- Normal (source-over): The overlay is drawn on top of the base at the specified opacity — the standard compositing mode for watermarks and logos.
- Multiply: Multiplies pixel values, darkening the result — ideal for adding shadows, textures, and dark overlays to photos.
- Screen: Inverts, multiplies, and inverts again — lightens the result and is perfect for double exposure and light leak effects.
- Overlay: Combines Multiply and Screen based on base pixel brightness — increases contrast and is widely used for texture and grunge overlays.
Important Limitations
The output canvas uses the base image dimensions — the overlay is scaled and positioned within that space. For JPEG output, transparent pixels in the overlay are filled with white before encoding. Very large images (above 20 MP) may be slow to process depending on your device. The image stacker does not support animated GIFs — only the first frame is used.
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Frequently Asked Questions About Image Stacker & Overlay
An image stacker and overlay tool lets you composite two images together — placing one on top of the other with configurable blend mode, opacity, scale, and position. Our free image stacker uses the Canvas API to process images locally in your browser, so your files never leave your device.
The tool supports all 16 standard CSS/Canvas blend modes: Normal, Multiply, Screen, Overlay, Darken, Lighten, Color Dodge, Color Burn, Hard Light, Soft Light, Difference, Exclusion, Hue, Saturation, Color, and Luminosity — the same modes available in Photoshop and CSS mix-blend-mode.
Yes. All image stacking and overlay processing happens locally in your browser using the Canvas API. Your images are never uploaded to any server, never stored, and never leave your device. Complete privacy is guaranteed.
Yes — 100% free, forever. No signup, no account, no premium tier, no file size limits, and no ads. Stack and overlay as many images as you need.
Yes. You can align the overlay using presets (top/center/bottom and left/center/right) or switch to custom mode and enter exact X/Y pixel coordinates. You can also add pixel offsets on top of any alignment preset for fine-tuning.
Yes. The overlay scale slider lets you resize the overlay from 5% to 200% of its original size. The overlay is scaled proportionally and positioned according to your alignment settings.
You can download the merged image as PNG (lossless, supports transparency), JPG (smaller file size, no transparency), or WebP (best compression with transparency support). PNG is recommended when the overlay has transparent areas.
Yes. PNG overlays with transparency are fully supported. The transparent areas of the overlay will show the base image through, which is ideal for logo watermarks and icon overlays. For JPEG output, transparent areas are filled with white.
The output image always uses the base image dimensions (width × height). The overlay is scaled and positioned within that canvas. If the overlay extends beyond the canvas edges, it is clipped to the base image boundaries.