There are many places where you can find Apps to use in your courses. You can add external apps in the Canvas App Center, the Edu App Center, or through vendor-provided tools.
Once configured, external apps may be able to be added to Modules, Course Navigation, the Rich Content Editor, and Assignments. The external app should include information about where the app can be placed in Canvas.
Located in Course Settings, the App Center is your gateway to powerful teaching tools that are easily integrated into a Canvas account or Canvas course. These apps can be installed into Canvas with one click.
The Edu App Center is an index lists of all current Canvas-compatible External Apps and is updated frequently.
Many vendors use their own external tool integrations. Vendors will have their own landing pages with instructions on how to configure and use the tool. Some vendors may provide a common cartridge that will import the tools for you. However, any app used by a vendor will require a key and secret provided by the vendor and need to be configured manually, by URL, or by XML.