ESX is the oldest of the popular roleplay frameworks on FiveM and still the one you meet most often. Over the years it split into several lines — older servers sit on 1.1 and 1.2, new ones are built on ESX Legacy, which is developed today as esx_core. The differences are not cosmetic: exports and the way you fetch the player object changed between versions, so a script from a few years ago can fall over on a fresh install.
In practice two things cause most of the trouble. The first is the inventory — some servers stayed on the old esx_inventoryhud, others moved to ox_inventory, and those register items in completely different ways. The second is the database layer: mysql-async has been unmaintained for a long time and oxmysql is the standard. We write against oxmysql and ox_inventory, and where a specific resource supports more, its product page says so.
Installation is standard: folder into resources, ensure resource_name in server.cfg, and import the SQL file if the script stores anything. The resource has to start after es_extended and after the inventory — in the wrong order the console throws nil errors, because the script is reaching for something that does not exist yet.
The catalogue covers garages, vehicle shops, HUDs, production and distribution systems, jobs and emergency-service tools. The filter at the top narrows it to free or paid. If you are not sure whether something fits your setup, ask on Discord before buying — checking is faster than undoing.