Understanding Compress Images Online
Compress PNG, JPG, WEBP, and AVIF images in batches while controlling quality and preserving practical visual detail.
How image compression reduces file size
The compressor decodes PNG, JPG, WEBP, or AVIF input and re-encodes it with the selected quality. It can remove nonessential metadata and use the server image library’s optimized encoder settings. Dimensions remain unchanged, so the result targets encoding weight rather than pixel count.
Lossy formats reduce less-visible detail through quantization and prediction. PNG uses lossless filtering and DEFLATE compression, so its savings depend on repeated colors, flat regions, palette opportunities, and metadata rather than photographic quality alone.
Choosing a practical quality setting
A value between 80 and 88 is a strong starting point for web photographs. Lower values can save more bytes but may soften texture, create ringing around high-contrast edges, or produce banding in smooth gradients. Logos and interface graphics often need lossless PNG or a high-quality transparent WebP/AVIF output.
Compare the result at its actual display size, not only while zoomed in. The best setting is the smallest file that still looks clean in the real page layout.
Compression, resizing, and responsive delivery
Compression and resizing solve different problems. Compression changes how pixels are encoded; resizing changes how many pixels exist. A 4000-pixel camera image can remain large even after aggressive compression if the page only displays it at 800 pixels.
For strong performance, resize to realistic display dimensions, create responsive variants, encode efficiently, and set explicit width and height attributes to reduce layout movement.
Metadata and privacy
Image files may contain camera model, timestamps, editing software, comments, thumbnails, and GPS coordinates. Re-encoding commonly removes much of this metadata, reducing size and limiting accidental publication of private information.
Do not treat metadata stripping as a forensic privacy guarantee. Review sensitive originals with dedicated metadata tools before public distribution.
Temporary processing model
Every file receives a separate upload progress indicator and a random staging token. The server stores files below a blocked storage directory and serves results through expiring download routes instead of exposing filenames or directories.
The included cron script deletes assets older than thirty minutes. This retention policy protects shared hosting disk space and means recent-history download links naturally expire.
Frequently asked questions
Does compression resize the image?
No. This tool preserves width and height. Use the image resizer when you also need fewer pixels.
Which formats can I compress?
PNG, JPG/JPEG, WebP, and AVIF are accepted when the matching server codec is available.
Why can a PNG stay large?
PNG is lossless. Detailed photographs and noisy textures are harder for its filters and DEFLATE compression to reduce.
Are there batch limits?
The application does not impose a file-count limit; server upload and memory settings remain the practical limits.