Every key, blank and programmer.
Found by its code.

It matters completely. A remote on the wrong frequency will never pair, however carefully it is programmed, because the receiver in the car is listening on one band only. North American vehicles are usually 315MHz and European and Asian models usually 433MHz, but there are exceptions inside a single model year, so read the figure off the fob rather than assuming it. It is normally printed on the circuit board next to the crystal.

The chip decides the whole job, because it decides whether a key can be cloned or has to be programmed to the car. The families you meet most are ID46, ID47, ID48, ID49, 4C, 4D and 8A. ID46 and the 4D family can usually be cloned onto a blank in a couple of minutes with no connection to the vehicle at all. ID47, ID49 and 8A are rolling code parts and generally have to be written through the immobiliser. If the chip is not printed on the key itself, a transponder reader identifies it in seconds. Every product page here states the chip where we hold it confirmed, and leaves it blank where we do not.

They solve opposite halves of the same job, which is why most locksmiths end up owning both. A cutting machine shapes the metal so the key turns the lock. A programmer talks to the immobiliser so the car accepts the key and starts. Cut but not programmed, the key turns and the engine will not fire. Programmed but not cut, nothing turns at all. Start with whichever half you currently pay somebody else to do.

The FCC ID identifies the radio module inside the remote, and it is the single most reliable thing to search on, because it narrows a fob to one exact part instead of a family that looks identical in photographs. It is moulded into the back of the case or printed on the board inside, and it usually opens with a short letter group such as HYQ or KR5. Paste it straight into the search box at the top of this page. If the case is broken and the code is gone, the OEM part number on the board is the next best identifier.

Often, but it depends on the vehicle rather than on the tool, and it is the question worth settling before you buy anything. Some immobilisers accept an all keys lost procedure over the OBD port in minutes. Others need the module read on the bench, which means taking it out of the car, and some need a PIN read separately before anything can be written at all. Every tool listed here states which procedures its manufacturer supports on its own page. We will not tell you a platform covers your vehicle unless the manufacturer says so.

It reads the lock instead of the key. You pick the wafers and the tool decodes the cuts as you go, so you leave with the bitting written down and can cut a working blank with no original and without pulling the lock out of the door. Each tool is ground for one keyway, so it is chosen by keyway code and never by vehicle make: an HU100 tool works on every lock using that profile, whatever badge is on the bonnet.