Readdle

Readdle is a Ukrainian mobile application development company. The company research and development is based in Odesa, Ukraine. The operation is mostly built around the App Store, cumulatively generating over 100 million downloads. The company was founded by former college roommates Igor Zhadanov, Alex Tyagulsky, Andrian Budantsov, and Dmitry Protserov.

Documents
Documents (previously ReaddleDocs) is a file management application. The app was Readdle's first product, and was developed because co-founders Alex Tyagulsky and Andrian Budantsov wished to be able to read books on their iPhones. It was initially released as a Safari-based web service in 2007. Later, Apple asked Readdle to submit the app (then called ReaddleDocs) to become one of the 500 apps available on the App Store when it launched on July 10, 2008. After Wall Street Journal writer Walt Mossberg endorsed the app, sales increased ninefold, netting the company $500–1000 a week. In 2013, the app rebranded as Documents.

PDF Expert
PDF Expert is a PDF editing app for iPhone, iPad and Mac. The app allows a user to read, annotate and edit PDFs, change text and images, fill in forms and sign contracts.

PDF Expert was initially launched for iOS in 2010 for the first iPad and is now supported on the iPad, iPhone, and Mac.

Spark
Spark is an email application for Windows, iOS, macOS, and Android devices. Lifehacker wrote that Spark was the best alternative for Mailbox users when that service went offline. It was released on April 2, 2019, and was Readdle's first app released on Android.