|Initial release||May 29, 2015|
|Operating system||Windows, Android, macOS, iOS|
|Platform||Android Nougat and later, MacOS High Sierra and later, iOS 13.4 and later|
|Size||67.06 MB (Android), 175 MB (iOS), 58.6 MB (macOS)|
Spark is an email application for Windows, iOS, macOS, and Android devices by Readdle. Lifehacker wrote that Spark was the best alternative for Mailbox users when that service went offline.
On April 2, 2019, Readdle released Spark for Android, the company's first mobile application for the Android platform.