LINE Front-end Framework (LIFF) Development Reference & API Guide

Overview

The LINE Front-end Framework (LIFF) allows developers to build rich web applications running inside the LINE app (in-app LIFF browser) or in external web browsers. This guide provides full reference specifications for the LIFF SDK (v2.x), covering environment checks, initialization, authentication, user context, profile retrieval, messaging, permanent links, and error handling.

Official Documentation Reference: LINE LIFF API Reference (index.html.md)

When to Use

• Building web apps that run inside the LINE in-app browser or standard web browsers.
• Initializing the LIFF SDK using liff.init({ liffId }).
• Handling user authentication (liff.login(), liff.logout(), liff.isLoggedIn()).
• Retrieving user details (liff.getProfile(), liff.getDecodedIDToken(), liff.getAccessToken()).
• Retrieving runtime context (liff.getContext(), liff.getOS(), liff.getLanguage(), liff.isInClient()).
• Sending messages or sharing content (liff.sendMessages(), liff.shareTargetPicker()).
• Generating permanent LIFF URLs (liff.permanentLink.createUrl()).
• Handling error objects (LiffError) and debugging LIFF app initialization issues.