The 7 Best Free Image Compression Tools in 2025

Last month I had to optimize 500+ product images for a client's e-commerce site. After trying nearly every tool out there, I learned which ones actually work and which ones are just hype. Here's my honest breakdown.

Why Image Compression Matters

Before diving in, here's the reality: unoptimized images account for about 38% of a webpage's weight on mobile. That directly hits your Core Web Vitals and, ultimately, your Google rankings. Getting compression right isn't optional anymore.

The Tools I Tested

1. TinyPNG

The old reliable. TinyPNG has been around forever, and it still does a solid job. You can process up to 20 images at once (max 5MB each), and the compression is genuinely impressive for PNGs.

Pros: Dead simple interface, good PNG compression, free tier is generous.

Cons: JPEG compression is okay but not exceptional, 5MB limit can be annoying for larger files, requires upload to their servers.

2. ShortPixel

ShortPixel consistently delivered the best JPEG compression in my tests. It reduced one test image from 2.1MB to 1.13MB while TinyPNG got it to 1.7MB. That's a significant difference when multiplied across hundreds of images.

Pros: Best-in-class JPEG compression, supports WebP and AVIF conversion, 10MB file limit, three compression modes (lossy, glossy, lossless).

Cons: Slower processing speed, free tier limited to 100 images/month, images uploaded to external servers.

3. Squoosh

Google's open-source tool is impressive. It runs entirely in your browser using WebAssembly, so your images never leave your device. You get real-time previews and fine-grained control over compression settings.

Pros: 100% private (local processing), excellent visual comparison tool, supports modern formats like AVIF.

Cons: One image at a time (no batch processing), can be resource-intensive on older devices.

4. Small.im

This is where things get interesting. Small.im combines the privacy benefits of local processing with the convenience of batch operations. I compressed 50 images in under a minute, all without uploading anything to external servers.

Pros: Processes everything locally in your browser, unlimited batch processing, no file size limits, supports conversion between JPG/PNG/WebP/AVIF/GIF/SVG, completely free with no registration, works offline.

Cons: Heavy processing can be demanding on older hardware (though this applies to any WebAssembly-based tool).

5. Optimizilla

A straightforward tool that combines lossy and lossless compression. The quality slider lets you find the sweet spot between file size and image quality.

Pros: Mix different formats in the same batch, intuitive quality control, 100% free.

Cons: Limited to 20 images per batch, requires server upload.

6. Compressor.io

Supports JPG, PNG, GIF, and SVG with both lossy and lossless options. The interface is clean and the results are consistent.

Pros: SVG support is rare, good quality preservation, simple drag-and-drop.

Cons: One image at a time, images processed on their servers.

7. ImageResizer.com

Been around since 2012, compresses millions of images. The 80% compression rate is solid for most use cases.

Pros: Process up to 50 images at once, no registration or watermarks, long track record.

Cons: Less control over compression settings, server-side processing.

My Recommendation

For privacy-conscious users or anyone handling sensitive images: Small.im or Squoosh. Your data never leaves your device.

For maximum JPEG compression: ShortPixel delivers the smallest files.

For quick one-off tasks: TinyPNG remains the easiest option.

For batch processing without limits: Small.im is hard to beat - unlimited images, no registration, and it all happens locally.

Quick Comparison

Tool	Batch Processing	Privacy	File Limit	Best For
TinyPNG	20 images	Server	5MB	Quick PNG optimization
ShortPixel	50 images	Server	10MB	Maximum JPEG compression
Squoosh	1 image	Local	None	Fine-tuned control
Small.im	Unlimited	Local	None	Privacy + bulk processing
Optimizilla	20 images	Server	None	Mixed format batches

The bottom line? Choose based on your priorities. If privacy matters (and in 2025, it should), go with browser-based tools that process locally. If you need the absolute smallest file sizes for JPEGs and don't mind server uploads, ShortPixel is your best bet.