Are my images uploaded to a server?

No — all image processing uses the HTML5 Canvas API directly in your browser. Images are read via the File API and drawn to a canvas element, then exported as a new file. Nothing leaves your device.

What image formats can I upload?

The tool accepts any image format your browser supports: JPEG, PNG, WebP, GIF (first frame only), BMP, AVIF, and SVG rasterized to a canvas. The output format can be JPEG, PNG, or WebP regardless of the input format.

What is the difference between JPEG, PNG, and WebP output?

JPEG is best for photographs — it uses lossy compression and supports a quality slider. PNG is lossless and best for graphics with text or sharp edges. WebP is a modern format that achieves smaller file sizes than JPEG at the same quality level and is supported by all modern browsers.

How does the quality slider work?

The quality value (1–100) maps directly to the Canvas API's encoderOptions parameter when calling toDataURL('image/jpeg', quality/100). A quality of 85 is typically indistinguishable from 100 at a significantly smaller file size.

How does Download All as ZIP work?

After processing, clicking Download All as ZIP uses the JSZip library (loaded from CDN) to package all processed images into a single .zip file in memory, which is then downloaded to your device without any server involvement.

Media 無料サインアップ不要

Photo Resizer & Compressor

Resize and compress images in the browser using Canvas API — by percentage, exact dimensions, or max dimension — with batch processing and ZIP download.

ツールを読み込み中…

このツールについて

Resize and compress photos entirely in your browser without uploading them to any server. Drag and drop one or multiple image files onto the upload area to add them to the batch queue. Three resize modes give you full control: Percentage mode scales images by a percentage of their original size (10–200%); Exact Dimensions mode sets a specific width and height; Max Dimension mode fits the longest side within a pixel limit while automatically maintaining proportions. The aspect ratio lock toggle keeps width and height proportional in Exact Dimensions mode — type either dimension and the other updates automatically. Choose the output format: JPEG and WebP support a quality slider (1–100) for fine-grained control over compression; PNG uses lossless compression. Each image in the queue shows a before/after comparison: the original filename, original dimensions and file size, and the estimated new dimensions and file size after processing. Click Process to apply the resize and compression to all images. Download individual processed images with a single click, or use the Download All as ZIP button to bundle all results into a single ZIP archive using JSZip. A progress bar tracks batch processing status.

使い方

1 Drag and drop images onto the upload area, or click 'Choose Files' to select one or more images.
2 Select a resize mode: Percentage, Exact Dimensions, or Max Dimension.
3 Choose the output format (JPEG, PNG, or WebP) and set the quality slider for JPEG/WebP.
4 Toggle 'Lock Aspect Ratio' to maintain proportions when entering exact dimensions.
5 Click 'Process All' to resize and compress every image in the queue.
6 Click the download icon on individual images or 'Download All as ZIP' to save the results.

このツールについて

使い方

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