Now iPhone and iPad users can take advantage of popular paid iOS apps on sale for free, reports BGR. From cool camera apps to creating a fun paper keyboard, these paid iPhone and iPad apps have been made available for free by their developers for a limited time.

Building apps can be a lucrative venture for developers if the app catches on with consumers. Offering an app free is one way to get consumers to discover it, try it and, hopefully, buy it.

The mobile application sales below could end in an hour or a week from now. If you click on a download link and see a price listed instead of the word "free," the app is no longer free. If you chose to download the app after the sale has ended, you will be charged the regular price.

Paper Keyboard

This app allows you to print a PDF file on paper and use it as a keyboard. Place your iPhone where marked on the paper and the phone's camera detects your fingers with cutting-edge algorithms. Play games, use the typing test and more. Download Paper Keyboard. Regular price $0.99.

ProCam 2

Get a professional camera experience both in camera functionality and user interface with your iPhone using ProCam. The app is easy to use for beginners who want customized settings to create the best photos and videos. Download ProCam 2 for iPhone or download ProCam XL 2 for iPad. Regular price $1.99.

ACDSee

The ACDSee iPhone app gives you an innovative camera, a state-of-the-art photo editor and a collage maker along with all the tools needed to get the best mobile photography experience. Download ACDSee. Regular price $1.99.

TotalReader Pro

The TotalReader Pro claims to be the best application for reading books in any format. All formats are 100 percent supported, including the styles, chapters, tables, links and more. Download TotalReader Pro. Regular price $4.99.

MyKees

The MyKees app allows you to fully customize your iPhone or iPad keyboard by color, text size and more. Download MyKees. Regular price $0.99.

City Weather

The City weather app shows the temperature and weather details of any location or city worldwide with attractive animations. Download City Weather. Regular price $1.99.