Guides
Written by the people building the tools, edited before publishing, and dated so you can judge how current they are. Where we are describing typical behaviour rather than something we have measured, we say so.
How-to · 7 min read
How to hit a 50 KB limit without wrecking the photo
The order of operations that keeps a heavily compressed photo looking like a photo, and the one mistake almost everyone makes first.
Updated 1 September 2026
Troubleshooting · 6 min read
Why an upload form keeps rejecting your file
Size caps, dimension caps and format checks look identical from the outside — the error message is usually the same unhelpful sentence. Here is how to tell them apart.
Updated 1 September 2026
Technical · 11 min read
What happens when a browser compresses an image
Decoding, colour transforms, discrete cosine transforms and quantisation — where the quality actually goes, and why doing it in a tab is now realistic.
Updated 1 September 2026
Comparison · 9 min read
JPEG, PNG, WebP or AVIF: choosing by content
A decision path based on what is actually in the image, rather than on which format is newest.
Updated 1 September 2026