What it does
MIT App Inventor is a browser-based environment for building Android and iOS applications, especially in educational settings. Its Designer is used to arrange an app's interface, while a separate Blocks Editor connects visual programming blocks to define behavior. The service is free to use and provides tutorials for projects ranging from a first button-and-sound app to maps, sensors, and cloud-connected examples. A phone or tablet can run the free Companion app for testing.
From screen layout to app behavior
The official site offers working tutorial projects, including Hello Purr, a beginner exercise using a button and sound. Open a project in the browser, arrange its interface in the Designer, then switch to the Blocks Editor to connect the blocks that control what happens when someone uses the app. The two-part design makes the relationship between a visible component and its behavior concrete without requiring learners to begin by writing source code.
For a first project, follow the instructions beside a tutorial, then connect a phone or tablet with the MIT AI2 Companion app to try the result on a device. The official site also describes options to save an app to a phone or build an installable app. Tutorials progress from basic interactions to examples involving location, cameras, machine learning, and shared cloud data, so the same environment can support more than introductory exercises.
The editor itself runs in a browser on a Mac, Windows computer, or Chromebook and needs no local installation. This is a visual app-building environment, not a general-purpose text editor: its workflow centers on the Designer, blocks, and mobile app components. The Companion app is a separate device-side tool used to check projects on a phone or tablet.
Strengths
- A browser-based Designer and Blocks Editor separate interface layout from app behavior.
- The official tutorials provide working starting projects and examples using components such as buttons, sound, maps, and sensors.
- The site describes building for Android and iOS and testing on a phone or tablet with its Companion app.
Watch out for
- The visual blocks and component workflow is specialized for app building rather than general-purpose source editing.
- Testing on a physical phone or tablet uses a separate Companion app; the editor and device test setup are not the same thing.
Best for
- Teachers and students introducing programming through small mobile app projects
- Prototyping Android or iOS apps that use the platform's visual components
Sources
- MIT App Inventor (Oct 26, 2026)
- Designer and Blocks Editor (Oct 26, 2026)
- appinventor-sources/LICENSE at master · mit-cml/appinventor-sources · GitHub (Oct 26, 2026)