Better Auth is a framework-agnostic authentication and authorization framework for TypeScript, designed as a monorepo with a core library, multiple database adapters (Drizzle, Prisma, Kysely, MongoDB, in-memory), client SDKs (React, Vue, Svelte, Solid, Expo, Electron), and a plugin ecosystem. It supports email/password, OAuth2/OIDC, SAML, SCIM, passkeys, 2FA, phone number OTP, and more. The architecture is modular: the core package provides the `betterAuth()` function, which configures plugins, database adapters, and social providers, and exposes a REST API for authentication flows. Client libraries use nanostores for reactive state management. The CLI offers project scaffolding, migration generation, and schema validation. External dependencies include jose for JWT, zod for validation, and various ORMs for database access. The codebase is well-tested with unit, integration, and e2e tests across all packages, and includes a release tooling package with AI-assisted changelog generation.