Check availability of personalized (vanity) plates on the CA DMV website.
python3 find_plate.py GOBEARS XKCD42 "HI MOM"
GOBEARS ... ✗ taken
XKCD42 ... ✓ AVAILABLE
HI MOM ... ✗ taken
Check as many plates as you want in a single run.
Python 3 (no third-party packages needed).
Hits the CA DMV's plate-check JSON API (checkPers.do) after establishing a session through their standard init/start handshake. Uses only Python standard library HTTP requests.