Is Image Shuttle free?

Yes, Image Shuttle is completely free with no hidden costs. All features can be used without limits and without creating an account.

Are my images uploaded to a server?

No. All processing in Image Shuttle happens locally in your browser using Canvas API, WebAssembly, and Web Workers. Your images never leave your device.

What image formats are supported?

Image Shuttle supports four major formats: JPEG, PNG, WebP, and AVIF. You can freely convert between these formats.

Will image quality decrease after compression?

It depends on the compression level you choose. With the 'High Quality' preset (85% quality), differences are nearly invisible to the naked eye. With 'Maximum Compression', there may be slight quality loss but significantly smaller file sizes. For PNG images, WebAssembly quantization is used — the quality preset maps proportionally to the quantizer target (85% maps to target 60, 70% to target 49, 50% to target 35).

How large can the images be?

Image Shuttle has no application-level size limit. The actual limit depends on your browser and device's available memory. Modern desktop browsers typically support images up to 16,384 × 16,384 pixels. If an image exceeds the browser's Canvas limit, processing will fail. For very large images, manually set maximum width/height to scale them down.

Why does PNG compression use WebAssembly?

PNG is a lossless format, and standard Canvas API compression has limited effectiveness. Image Shuttle uses libimagequant-wasm (a library compiled from a high-quality quantization algorithm to WebAssembly) for more efficient PNG compression, typically reducing file size by 50-80%. The quality preset maps proportionally to the quantizer's target value.

How many images can be processed simultaneously in batch mode?

Image Shuttle uses intelligent concurrency control, automatically adjusting the number of parallel processes based on your device's CPU cores (default: navigator.hardwareConcurrency). For example, an 8-core CPU can process 8 images simultaneously.

What are the advantages of WebP and AVIF formats?

WebP is 25-35% smaller than JPEG and 26% smaller than PNG, supporting transparency and animation. AVIF is a newer format, approximately 50% smaller than JPEG, supporting HDR and wider color gamuts. Both are recommended formats for modern web.

Can I resize an image to exact dimensions like 512×512?

Yes. In the Photo Editor, crop to the aspect ratio you need (e.g. 1:1), open Resize and type the target width (such as 512) — the height syncs automatically with the aspect-ratio lock. Apply and export to get exactly that size, with your choice of PNG/JPG/WebP format and compression quality.

What adjustments and filters does the Photo Editor support?

Adjustments cover brightness, contrast, saturation, hue, blur, sharpen, vignette and grain, plus grayscale/sepia/invert toggles — and 12 one-click filter presets (B&W, Noir, Vintage, Warm, Cool, Fade, Punch, Soft, Dramatic and more). You can also add text (9 font stacks including Chinese), 96 emoji stickers and 6 shape types, all draggable with full undo/redo.

What layouts does the Collage Maker support?

20 programmatic layouts are built in: regular grids (2×2 up to 4×2), feature-photo compositions and asymmetric mosaics, across 6 canvas ratios (1:1 to 9:16). Spacing, outer margin, corner radius and background color are all adjustable; photos can be panned and zoomed inside each cell, and the result exports at 2000px width.

Do custom canvas sizes in the Design Studio cost anything?

Completely free. Custom width/height from 64 to 4096 pixels, 8 social-media size presets (OG image, YouTube thumbnail, Instagram, Story and more), the layer system, gradient backgrounds and 10 starter templates cost nothing, and exports never carry a watermark — features many competitors paywall.

What's the difference between Image Shuttle and Squoosh?

Both process images locally in your browser, but they serve different needs: Squoosh is a single-image compression tool, while Image Shuttle is a full image studio — batch compression and format conversion plus a built-in photo editor (filters, text, exact-pixel resize), a collage maker and a design studio, with a bilingual UI and offline PWA support.

Image Shuttle について

ShuttleLab がお届けする、無料でプライベートなブラウザ内画像スタジオ — 圧縮、編集、コラージュ、デザイン

Image Shuttle とは？

Image Shuttle は、すべてブラウザ内で動作する無料のオンライン画像スタジオです。圧縮ツールとしてスタートし、今では 4 つのツールが 1 つに。JPEG / PNG / WebP / AVIF の圧縮・フォーマット変換、調整・フィルター・トリミング・ピクセル単位のリサイズが揃った画像エディタ、20 種類のグリッドレイアウトを備えたコラージュメーカー、レイヤー・テンプレート・自由なカスタムキャンバスサイズが使えるデザインスタジオです。従来のオンラインツールと違い、ファイルがアップロードされることは一切なく、すべての処理は Canvas API、WebAssembly、Web Workers を使ってあなたのデバイス上で行われます。

512×512 のアバターが必要ですか？ 1:1 でトリミングし、リサイズに 512 と入力して書き出すだけ。まさにそのサイズで、フォーマットも圧縮品質もあなたの選んだとおりに出力されます。透かしは一切なく、アカウント登録も不要。他のツールでは有料になりがちなカスタムキャンバスサイズも、ここでは無料です。ウェブ向けの画像最適化でも、スクリーンショットへの注釈付けでも、SNS カバーの作成でも、写真をグリッドに並べるコラージュでも、Image Shuttle はプライバシーのリスクゼロでこなします。

100% プライベート

すべての画像処理はブラウザ内でローカルに完結します。ファイルはアップロードされず、データは収集されず、第三者があなたの画像にアクセスすることもありません。

アカウント不要

すぐに圧縮を開始できます — 登録もメールもトラッキングも不要。画像をドロップするだけです。

オープンソースの精神

Image Shuttle は AGPL-3.0 ライセンスのオープンソースで、最新のウェブ標準の上に構築され、すべての処理をクライアントサイドで行います。

圧倒的な速さ

並列処理には Web Workers を、PNG 最適化には WebAssembly を活用し、Image Shuttle はネイティブ並みの速度でプロ品質の圧縮を実現します。

When should I use Image Shuttle?

1WordPress post image optimization

Before: 5MB origin images, LCP > 4s, low Google PageSpeed score

After: Compressed to 800KB, LCP drops to 1.5s, PageSpeed score improves by 30+

2E-commerce product image batch processing

Before: 200 product images totaling 1.2GB, 30 minutes to upload to CDN

After: Compressed to 300MB total, upload time reduced to 8 minutes

3Email attachment image compression

Before: 3 photos totaling 15MB, exceeding email attachment limits

After: Compressed to 3MB, sent successfully with no visible quality difference

4Converting legacy PNG images to modern WebP format

Before: Website uses many PNG screenshots, slow page loads

After: Converted to WebP with 35% size reduction, noticeably faster loading

5Social media image preprocessing

Before: Phone photos are 8MB, slow Instagram upload with server-side compression

After: Pre-compressed to 1MB, fast upload with quality under your control

How-To Guides

How to compress a single image

1Open the Image Shuttle website (image.shuttlelab.org)
2Drag and drop your image onto the upload area, or click to select a file
3Choose a compression quality preset (High Quality 85%, Balanced 70%, or Maximum Compression 50%)
4Click the 'Apply' button to start compression
5Use the slider to compare original and compressed results, then download when satisfied

How to batch-compress multiple images

1Select multiple images in the upload area (supports drag-and-drop multi-select)
2Adjust compression settings (quality, format, size limits)
3Click 'Apply' — the system will automatically process all images in parallel
4Once processing is complete, click 'Download All' to download all compressed files at once

How to resize an image to exact dimensions (e.g. 512×512)

1Open the Photo Editor (image.shuttlelab.org/editor) and upload your image
2In Crop, pick the target aspect ratio (e.g. 1:1), drag the selection to frame the image, then apply
3Open Resize and type the target width 512 — the height syncs automatically via the aspect-ratio lock
4After applying, the bottom status bar shows the output size (512 × 512 px)
5Click Download, choose PNG/JPG/WebP format and compression quality, and export

How to convert image format

1Upload the image you want to convert
2Select the target format in the format selector (JPEG, PNG, WebP, or AVIF)
3Adjust quality parameters as needed
4Click 'Apply' and download the converted file

Image Shuttle vs Similar Tools (as of 2026-05)

Feature	Image Shuttle	TinyPNG	Squoosh
100% Local Processing	✓	✗	✓
No Registration Required	✓	✗	✓
Batch Processing	✓	Paid	✗
Format Conversion	✓	✗	✓
WebP/AVIF Support	✓	✗	✓
WebAssembly PNG Compression	✓	✗	✗
Real-time Preview Comparison	✓	✗	✓
Photo Editing (filters/text/exact resize)	✓	✗	✗
Collage Maker & Design Studio	✓	✗	✗
Completely Free	✓	Free tier limited	✓

Frequently Asked Questions

初めての出会いが、旧友との再会のように感じられますように

Image Shuttle は ShuttleLab が心を込めて作った、完全無料でオープンソースのツールです。もし 1 枚でも画像の圧縮にお役に立てたなら、必要としている友人にシェアしていただくことが、私たちにとって何よりの応援です。

友人にシェアする

お問い合わせ

ご質問、フィードバック、サポートが必要ですか？

support@shuttlelab.org