Windows

Top 5 Free Online Image Compressors Compared (2025)

Looking to shrink image sizes without sacrificing quality? Whether you’re optimizing photos for the web, mobile apps, or SEO, choosing the right image compressor can make all the difference. In this guide, we have tested and compared the top free online image compressors of 2025 to help you find the best tool for your needs.

We evaluated key factors like compression performance, transparency support, processing speed, and—most importantly—privacy. When dealing with sensitive documents (such as passports, IDs, or confidential files), ensuring your data remains secure is critical. Some compressors process images entirely in your browser, while others upload them to remote servers, posing potential privacy risks. We highlight which tools offer local processing and which ones delete your files immediately after compression, so you can make an informed choice.

Stay tuned as we break down the pros, cons, and security features of each image/photo compressor, helping you strike the perfect balance between efficiency and peace of mind.

1. SkillToSky Image Compressor

Website: skilltosky.com/image-compressor

• ✔ 100% client-side — no upload to server
• ✔ Bulk compress up to 30+ images
• ✔ Supports JPG, PNG, WebP
• ✔ Preserves transparency in PNGs
• ✔ Shows before/after size and preview

Best for: Privacy, speed, and developers/designers needing precise quality control.

2. TinyPNG

Website: tinypng.com

• ✔ Great for PNG and JPG compression
• ✘ 5MB limit per file (free version)
• ✘ Upload required – files sent to cloud
• ✔ Keeps transparency in PNG

Best for: Simple drag-and-drop compression.

3. CompressJPEG / CompressPNG

Website: compressjpeg.com

• ✔ Supports JPG, PNG, PDF
• ✔ Batch compression
• ✘ Upload to server – privacy concerns
• ✘ No compression control or preview

Best for: Fast compression with minimal settings.

4. Squoosh by Google

Website: squoosh.app

• ✔ Client-side processing (no upload)
• ✔ Tons of compression formats (WebP, MozJPEG, AVIF)
• ✔ Live comparison slider
• ✘ Only one image at a time

Best for: Developers and enthusiasts testing compression formats.

5. ImageCompressor.com

Website: imagecompressor.com

• ✔ Bulk upload support
• ✘ Upload required
• ✘ Can be slow with large images

Best for: General-purpose compression with minimal setup.

Which Image Compressor Is Right for You?

Tool	Offline/Private	Bulk Upload	Transparency	Best Feature
SkillToSky	✔	✔	✔	Preview + No Upload
TinyPNG	✘	✔	✔	Popular & Simple
Squoosh	✔	✘	✔	Format Variety
CompressJPEG	✘	✔	✘	PDF Support
ImageCompressor	✘	✔	✘	Simplicity

Conclusion

If you’re looking for a free, private, and powerful tool to compress images without sacrificing transparency or privacy, SkillToSky Image Compressor stands out in 2025. Give it a try and shrink your PNGs, JPGs, and WebPs with zero uploads and instant results.