India, Nov. 10 -- The message lands in an actors' WhatsApp group late at night, between a dozen forwards. "Casting for a vertical series. Female lead, 22 to 28. Mumbai. Rs.3.5K/day incl. commission."

A year ago, a lead role like this was hard for a newcomer to find. Now posts like it turn up almost every day.

They are for microdramas: short drama series made to be watched on a phone held upright, on apps such as Kuku TV, Story TV, QuickTV and ZEE5's Bullet. About 110 million people in India now watch them, according to industry estimates. The apps have been downloaded about 450 million times, according to venture fund Lumikai. Viewers watch 1.2 billion episodes a day, according to a study by ShareChat and Moj with Kantar.Every one of th...