MSAL

MSAL, short for Microsoft Authentication Library, is a family of libraries from Microsoft that enables applications to authenticate users and obtain tokens from the Microsoft identity platform. It provides a consistent, cross‑platform API for acquiring access tokens and ID tokens to call protected resources such as Microsoft Graph or your own web APIs secured by Azure Active Directory (Azure AD) or Microsoft accounts. MSAL supersedes the older ADAL library and aligns with the v2.0 endpoints, supporting OpenID Connect and OAuth 2.0 flows.

MSAL implements authentication flows appropriate to each platform, including the authorization code flow with PKCE for public clients, device code flow for headless devices, and integrated Windows authentication on Windows. It also handles token caching and silent token renewal so users do not need to sign in repeatedly. The libraries support multi-tenant and single-tenant scenarios, as well as Azure AD B2C consumer identities, and can sign in users across multiple apps with single sign-on when configured.

MSAL is available for multiple languages and platforms, including .NET, JavaScript, Java, Python, Android, iOS, macOS, and Unity. Developers use MSAL to obtain access tokens for Graph, Office 365, and custom APIs protected by Azure AD, manage user accounts and sessions, and implement secure sign-in flows in web, mobile, and desktop applications.

Key benefits include a uniform API across platforms, built‑in token caching, refresh token handling, and alignment with modern authentication best practices such as PKCE. Microsoft maintains MSAL with documentation and samples to support integration of the Microsoft identity platform into a wide range of app types.