AppMakr / Infinite Monkeys used to offer a free version of our DIY app builder platform, creating mobile apps that were supported by banner ads running in them. However, we spoke to a lot of our app publishers and the general opinion was that people hated them. So, we have eliminated that plan and now offer our full platform starting from just $1 / month. Considering the many thousands of dollars it would cost to hand code a new app, we think it's a pretty good value!
For a more detailed explanation, see Jay's recent blog post.