Can you apply for a Thai visa without a flight planned to Thailand?

Apply a week before you buy your ticket

Upon application the website will say to apply within 3 months of flight date. So if you do apply now, make sure you put intended date no further than that. You don't need to book the flight, just look up an airline date and time for the flight number.

Some people are choosing to apply now because the dtv is getting harder and taking longer to be approved. Embassies are much more critical now compared to 6 months ago

You dont need a ticket, but they ask for planned dates of arrival and departure. If you plan 6months ahead, dont expect them to handle your application for a long time