Image Resizer
Resize images by size or percent, locally.
Image Resizer scales photos by exact dimensions or percentage in your browser. Keep aspect ratio, pick PNG/JPEG/WebP output, and download the result with memory guards for large images—no upload required.
How it works
Select a local image to read its dimensions, choose percentage or width/height mode, optionally keep aspect ratio, then resize via Canvas. wowTools enforces megapixel and edge limits before allocating the output canvas.
Benefits
- Dimension and percentage modes
- Aspect-ratio lock to avoid stretch
- Large-image memory guards
- Downloadable PNG, JPEG, or WebP
Use cases
- Fit screenshots into documentation widths
- Create thumbnails for galleries
- Downscale camera photos for the web
- Prepare app icons at target sizes
Best practices
- Downscale from high-quality originals
- Prefer WebP/JPEG for photos, PNG for UI
- Keep aspect ratio unless you intend to crop
- Check output dimensions before publishing
Common mistakes
- Upscaling tiny images and expecting sharpness
- Disabling aspect lock and distorting photos
- Ignoring megapixel errors on huge panoramas
- Assuming GIF animation survives resize
Privacy
Files stay on your device. Canvas processing never uploads pixels. Clear downloaded results on shared machines when finished.
Frequently asked questions
- Does Image Resizer upload my files?
- No. Decoding and resizing happen with Canvas APIs in your browser. Nothing is sent to a server.
- How does keep aspect ratio work?
- When enabled with both width and height, the image is fitted inside that box without stretching. With only one dimension set, the other is derived from the source aspect ratio.
- What is the megapixel guard?
- Decoded and output images cannot exceed 40 megapixels or an 8192px edge. Oversized sources are rejected with a clear error instead of crashing the tab.
- Can I resize animated GIFs?
- The browser decodes the first frame into a bitmap. Animation is not preserved—export is a still image in your chosen format.
- Which output formats are supported?
- PNG, JPEG, and WebP when your browser can encode them. If WebP encoding fails, switch to PNG or JPEG.
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