
Description: Substack is an email newsletter platform that allows writers and publishers to easily create, design, and distribute email newsletters. It aims to let freelance writers and bloggers build direct relationships with readers.
Type: Open Source Test Automation Framework
Founded: 2011
Primary Use: Mobile app testing automation
Supported Platforms: iOS, Android, Windows

Description: TinyLetter is an email newsletter service that allows users to easily create, send, and manage email newsletters. It has a simple editor for crafting newsletter content and customizing newsletter design.
Type: Cloud-based Test Automation Platform
Founded: 2015
Primary Use: Web, mobile, and API testing
Supported Platforms: Web, iOS, Android, API