Lindsay Lohan -- Accused of Stealing 'Virtual Closet' App

Lindsay Lohan has been accused of stealing before ... but never digitally -- which is exactly what one web developer says LiLo and her brother Michael Jr. have done.

Lindsay and MiLo allegedly struck a deal with a tech entrepreneur named Fima Potik to work on his startup called Spotted Friend ... according to the NY Post.

The app allows users to see what clothes celebrities have in their closet ... then gives the person a chance to buy the threads -- and the celebs get a cut of the profits

LiLo tweeted about Spotted Friend in July 2013 ... but for some reason, the group parted ways -- and last month the Lohans started raising money for a similar app.

Now MiLo Jr, Lindsay and their new business partner have reportedly been slapped with a cease and desist ... threatening swift legal action if she doesn't stop.