Simply visit Wordle’s website (https://www.powerlanguage.co.uk/wordle/), right-click on the page (or use a drop-down menu depending on your browser), choose “save page as a webpage,” and save it to your desktop. You should then see an HTML file on your desktop as well as a folder that’s labeled “wordle_files.” Clicking on the HTML file should open the game in your browser, even if you’re offline.
A bit more detail on how Wordle is built, from the Gizmodo link I posted:
And from Vice:
All the words have been pre-selected and are sitting there for anyone to view. People have already reverse-engineered the code and created bots that spoil the next day’s word. So, people are simply downloading the page to play an offline version of Wordle that can last for seven years.