They are like Christmas markets, but in better weather (except today as it snowed all day)!
There are three - Freyung, Am Hof and Schönbrunn.
Freyung and Am Hof are right next to each other. They run from April 1 - 18. Schönbrunn is at the palace. If you have time for one, then definitely do Freyung.
Freyung is special as the market centers around thousands of painted eggs for sale - a photography dream (let me know if you want my Instagram details for photos). Surrounding the market are food, wine and gift stalls. I like the Hungarian enamel jewelry and the decorative rolling pins.
One block away is Am Hof. This market is exactly like the Christmas market, with the same vendors. My highlight is the Speck Standl, where you can get great sausages.
I plan to visit the Schönbrunn market tomorrow, but have been many times in the past. Essentially like the Christmas market, but smalller and with eggs. I’ll add some context once I visit this year. Open April 2-19.