Rocket.Chat App
Self-hosted integration built on top of Rocket.Chat’s webhooks to deliver data into Rocket.Chat from on-premises tools like Jira, GitLab, and other popular products.
A Rocket.Chat App is an integration or a plugin created in an isolated environment, running locally within the Rocket.Chat environment. It enables the users to get more done with their server, with the flexibility of integrating their workflows and favorite apps, without the risk of losing data to an external server or having direct access to theirs, being run independently within their local environments.
You can also create your own App and publish it on our official Marketplace to share with the world. Users can download your application from the marketplace and use it.

How to install Rocket.Chat Apps?

Several apps are available to increase the productivity of your team's workflow. You can browse these apps either on our marketplace or access them directly from the Admin Panel.
To install Rocket.Chat apps from the marketplace, first, you need to register your workplace (even if it is a community edition ) on Rocket.Chat Cloud. Once your workplace is registered, you can install the apps from the marketplace from the Admin panel of your Rocket.Chat instance.
Different Rocket.Chat Apps can have different installation steps.
Upcoming sections are a few guides that will help you get started with Rocket.Chat App Engine to create and publish your own applications.

Webinar on Getting Started with Rocket.Chat Apps Development

We had a webinar some time ago on how to get started with Rocket.Chat Apps development. It is a bit outdated but can get you through the basics.
An updated guide can be found at Creating an App.