Overview

MentraOS is the operating system for smart glasses. A miniapp is an app that runs on the user’s phone, inside the Mentra App, and drives the glasses through the Mentra Miniapp SDK (@mentra/miniapp). You write a bundle, the user installs it from the Mentra Miniapp Store, and it runs on their device.

Building a mobile app that connects directly to glasses over Bluetooth? Use the Bluetooth SDK docs instead.

Looking for the @mentra/sdk cloud SDK? Apps used to be cloud-hosted servers built with @mentra/sdk. They’re now built on-device with the Mentra Miniapp SDK (@mentra/miniapp), which these docs cover. The older cloud SDK docs live at mentraglass.com/legacy.

How a miniapp is built

Every miniapp has two layers:

Background: an always-on JavaScript context (no DOM) that owns all the glasses logic: subscribing to the microphone, drawing to the display, reacting to button presses. It holds your session.
UI: an on-demand WebView (React + your styles) that opens when the user taps your miniapp’s tile, and is torn down when they leave. It has no direct hardware access; it talks to the background layer over a typed message bus.

This split exists so dozens of miniapps can stay resident on a phone without each one holding a heavyweight WebView in memory. See Two-layer architecture for the full picture.

Hello world

This background entry shows text on the glasses when the user presses a button:

src/background/index.ts

import { registerMiniapp } from "@mentra/miniapp/background";

registerMiniapp((session) => {
  // Runs once the miniapp connects. `session` is your handle to the glasses.
  // display.render() replaces the frame; a stable id updates the element in
  // place. Boxes are raw device px — see session.capabilities.display.
  const hud = { x: 0, y: 0, w: 576, h: 288 };
  session.input.onButtonPress(() => {
    session.display.render([{ type: "text", id: "hud", box: hud, text: "Hello from MentraOS!" }]);
  });

  // React to what the user says.
  session.transcription.on((data) => {
    session.display.render([{ type: "text", id: "hud", box: hud, text: data.text }]);
  });
});

You don’t new a server or call start(). The host evaluates your background bundle and hands you a session. Everything you do with the glasses goes through session.

The toolchain

Three npm packages, but you only ever invoke one of them directly:

Package	Role	Where it lives
`create-mentra-miniapp`	Scaffolds a new project. Run once via `bunx`, never installed.	N/A
`@mentra/miniapp`	The runtime SDK you `import` (`session.*`, React hooks).	your `dependencies`
`@mentra/miniapp-cli`	The `mentra-miniapp` CLI (`dev` / `pack` / `release`).	your `devDependencies`

create-mentra-miniapp writes a package.json that already pins the other two, so a single bun install brings everything down.

What you could build

Live captions that show spoken words on the HUD
Real-time translation for conversations
Hands-free note-taking triggered by a button or your voice
Navigation prompts on supported glasses
Teleprompters, fitness coaches, inspection checklists, and more

Next steps

Quickstart

Scaffold, run, and load a miniapp on your phone in minutes.

Two-layer architecture

How the background and UI layers work and talk to each other.

The session

The object that connects you to the glasses.

Mobile Bluetooth apps

Connecting to glasses directly over BLE instead.

Getting Started

Core Concepts

UI Layer

Display

Audio & Speech

Sensors & Input

Camera

Phone & System

Data

Reference

How a miniapp is built

Hello world

The toolchain

What you could build

Next steps

Quickstart

Two-layer architecture

The session

Mobile Bluetooth apps

​How a miniapp is built

​Hello world

​The toolchain

​What you could build

​Next steps

Quickstart

Two-layer architecture

The session

Mobile Bluetooth apps

How a miniapp is built

Hello world

The toolchain

What you could build

Next steps