Table of Contents
Image compression tools produce meaningfully different results depending on the image type you are compressing. TinyPNG's colour quantisation algorithm is exceptional for flat-colour PNGs but only average for photographs. Squoosh gives the most precision but requires manual settings. Browser-based tools with automatic quality selection trade control for convenience.
No single tool wins across every image type. This comparison covers four widely used free compressors — TinyPNG/TinyJPG, Squoosh (Google), iLoveIMG, and LevnTools — evaluating each for the five image types where the differences between tools are most significant.
Tools Tested
TinyPNG / TinyJPG: Proprietary lossy compression using colour quantisation for PNG and JPEG. Free tier: 5MB per file, 20 files per batch. Upload required.
Squoosh (Google): Open-source browser-based compressor with multiple codec options (MozJPEG, OxiPNG, WebP, AVIF, JpegXL). No upload, no file size limit. Requires manual quality settings — no auto mode.
iLoveIMG: Web interface supporting JPEG, PNG, and GIF compression. Upload required. Free tier has file count restrictions.
LevnTools Image Compressor: Browser-based, no upload, no file size limit, auto quality settings with manual override.
Which Tool Wins for Each Image Type
The right tool depends on what you are compressing, not on which one has the most users.
JPEG photographs: MozJPEG (used by Squoosh at quality 80) is the best open-source JPEG encoder available and consistently outperforms standard libjpeg on quality-to-size ratio. TinyJPG is close behind and requires less manual effort. Both produce imperceptibly different results from the original at 75–80% quality settings. iLoveIMG and browser-based auto-compressors perform similarly. The main differentiator for large camera files (10–25MB) is the 5MB per-file limit on TinyJPG's free tier — those files require Squoosh, iLoveIMG, or a browser-based tool.
PNG with flat colours (logos, icons, UI elements): TinyPNG's colour quantisation algorithm is purpose-built for this image type and achieves the highest PNG-to-PNG reduction — typically 60–80% on logos and flat-colour graphics. It works by reducing the colour palette from 24-bit to 8-bit using a perceptual algorithm that selects which colours to merge. Browser-based quantisation achieves similar results but is typically 5–10% behind TinyPNG on flat-colour images.
PNG with gradients (illustrations, screenshots): TinyPNG's quantisation causes visible banding on gradients because reducing to 256 colours cannot represent smooth colour transitions accurately. Squoosh in lossy WebP mode avoids this — WebP handles gradients without banding because it uses DCT-based compression rather than palette reduction. For gradient-heavy images, any WebP converter produces better results than TinyPNG's palette quantisation.
Logos with transparency: All tools preserve alpha transparency in PNG output. Squoosh in lossless WebP mode typically achieves the smallest transparent file. TinyPNG maintains transparency but occasionally softens sharp text edges slightly. For logos where edge crispness is critical, Squoosh lossless WebP or OxiPNG are the better choices.
Raw camera images (10MB+): TinyPNG/TinyJPG rejects files above 5MB on the free tier. Squoosh, iLoveIMG, and browser-based tools handle large files without restrictions. MozJPEG at quality 75–80 via Squoosh achieves the best ratio for raw camera JPEG — typically 75–85% reduction with no perceptible quality loss at web display sizes.
Compress images in your browser— No file size limit, no upload, supports JPEG and PNGWhen Each Tool Wins
TinyPNG wins: Flat-colour PNGs under 5MB where its colour quantisation achieves the best PNG-to-PNG ratio. Its JPEG compression is also solid for files under 5MB.
Squoosh wins: Maximum quality control, AVIF or WebP output, files over 5MB, gradient images where PNG quantisation causes banding (WebP handles gradients without banding). Requires more manual adjustment.
LevnTools wins: Files over 5MB, privacy-sensitive images, no-account no-upload requirement, JPEG and PNG from the same tool with auto settings.
iLoveIMG: Offers acceptable compression for routine images but does not lead in any test category. It adds GIF compression which the others handle inconsistently.
Privacy and Practical Constraints
TinyPNG and iLoveIMG both require uploading files to their servers. Squoosh and LevnTools process images entirely in the browser.
For images of unreleased products, private photography, client work, or any image with commercial sensitivity, browser-based compression is the appropriate choice.
For routine website images, stock photos, and non-sensitive visual assets, the upload-based tools perform comparably and the privacy trade-off is minimal.
File size limits: TinyPNG is the most restrictive at 5MB. iLoveIMG varies by plan. Squoosh and LevnTools have no meaningful upper limit.
Frequently Asked Questions
What is the best free image compressor for JPEG files?
What is the best free PNG compressor?
Does image compression affect quality?
Which image compressor works for files over 5MB?
Summary
No single image compressor wins across all image types. TinyPNG leads on flat-colour PNGs under 5MB. Squoosh provides the best precision control and WebP/AVIF output quality. LevnTools handles large files and privacy-sensitive content without upload requirements. Picking the right tool for the specific image type and constraint (file size, privacy, format) produces significantly better results than defaulting to one tool for everything.