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.

What's the difference between Image Shuttle and Squoosh?

Image Shuttle is inspired by Google's Squoosh project but uses a completely different tech stack. Squoosh uses Rollup while Image Shuttle uses Next.js for modern deployment. Both embrace client-side processing, but Image Shuttle has more robust batch processing and concurrency control.

About Image Shuttle

A fast, private, browser-based image compression tool by ShuttleLab

What is Image Shuttle?

Image Shuttle is a free online image compression and format conversion tool that processes everything directly in your browser. Unlike traditional image compressors that upload your files to remote servers, Image Shuttle uses modern web technologies — Canvas API, WebAssembly, and Web Workers — to compress and convert your images without ever leaving your device.

Built by ShuttleLab, Image Shuttle supports JPEG, PNG, WebP, and AVIF formats with intelligent compression algorithms that reduce file size by up to 80% while maintaining visual quality. Whether you need to optimize images for the web, reduce storage space, or convert between formats, Image Shuttle handles it all with zero privacy risk.

100% Private

All image processing happens locally in your browser. No files are uploaded, no data is collected, and no third parties can access your images.

No Account Required

Start compressing immediately — no sign-up, no email, no tracking. Just drop your images and go.

Open Source Spirit

Inspired by Google's Squoosh project, Image Shuttle embraces the same philosophy of client-side processing with modern web standards.

Lightning Fast

Leveraging Web Workers for parallel processing and WebAssembly for PNG optimization, Image Shuttle delivers professional-grade compression at native speed.

Inspired by Squoosh

Image Shuttle was inspired by Google Chrome Labs' Squoosh project. While Squoosh uses a custom build system, Image Shuttle is built with Next.js and modern web standards for better maintainability and deployment.

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 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	✓	✗	✓
Completely Free	✓	Free tier limited	✓

Frequently Asked Questions

Meeting you for the first time feels like the return of an old friend

Image Shuttle is crafted with care by ShuttleLab — completely free and open source. If it has helped you compress even a single image, sharing it with friends who need it is the best support we could ask for.

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Get in Touch

Have questions, feedback, or need support?

support@shuttlelab.org