Word Unscrambler on Apps is a deliberately small program. You type letters. It rearranges them against a word list shipped with the page. The interesting design choice is not the UI — it is where the work happens.
What “client-side” means here
Once the page and its word list have loaded, matching runs in your browser’s JavaScript. The tool does not POST your letter string to a remote solver. That matters for two reasons: privacy is simpler to explain, and the tool still works if the network blips after the first load.
Hosting still sees ordinary request logs when you open the page (IP, user agent, path). That is normal for any hosted site. What it does not need is a second channel that receives every scramble you try.
The boring tradeoff
A bundled list is finite. It will miss slang, brand-new coinages, and some proper nouns. A cloud dictionary could stay fresher — and would also turn a typing helper into a data collection point. For anagram play and casual word games, a fixed list is enough.
If you need an official Scrabble or tournament authority, this is the wrong tool. I say that on the product page for a reason.
What I refuse to do
I will not wrap a thin form around someone else’s API and call it a product. If the word list changes, that change ships as an Apps update you can inspect. If the matcher is wrong, the bug is in code I control.