California has its own tax website fairly similar to TurboTax called CalFile. One of the devs is even here on HN. Unfortunately CalFile seems to be intentional

California has its own tax website fairly similar to TurboTax called CalFile. One of the devs is even here on HN. Unfortunately CalFile seems to be intentionally gimped e.g. only usable if you're under a certain income threshold and technically you're not supposed to use it if you have capital gains or loses (but since cap gains are treated as regular income in CA it works fine if you still use it)