SMTP4Dev is a lightweight application designed to help developers test their applications and websites that are built on the SMTP protocol. The app works as a local SMTP server and allows developers to easily test their applications without configuring or setting up a real SMTP server. It captures all emails sent from their programs and displays them in an easy-to-view web interface. It also provides a debugging mode and supports TLS/SSL for secure connections. This makes it an ideal tool for developers who need to quickly and easily test their SMTP-based applications.
smtp4dev is a local system, mailtrap is an online service