The popular extensions for the Path of Exile 2 trade site exist almost only for Chrome. PoE2 Trade Monkey brings their features to every browser as a userscript, made for Violentmonkey in Firefox.
A sidebar on the right holds bookmarks in folders, a history and pinned items. Bookmarks always open in the league you are playing right now, so they still work next league. That is possible because trade2 search ids contain the full search but no league. Pinned items remember their search and lead you back to it even after you searched for something else.
On top of that there is a quick filter bar that stays at the bottom of the screen together with Search and Clear, a two-column layout, highlighted mods, plus and minus on every mod to filter by it, grouped identical listings, prices in divine and exalted via poe.ninja and favorites in the stat dropdown. Every feature can be switched off on its own, and the interface follows the trade site's language.
The script sends no searches of its own, does not poll the trade API in the background and never clicks whisper or "Travel to Hideout". It only works with the data the page loads itself. How it was built is in the blog post.