Better Auth Core (TypeScript)

Goals

• Set up a Better Auth instance with environment variables and data layer wiring.

• Wire server handlers and a client instance.

• Use sessions and server-side API methods safely.

• Keep data-layer choices pluggable (drivers or adapters).

Quick start

• Install better-auth .

• Set BETTER_AUTH_SECRET (32+ chars) and BETTER_AUTH_URL .

• Create auth.ts and export auth .

• Provide database (driver or adapter) or omit for stateless sessions.

• Mount a handler (auth.handler or a framework helper).

• Create a client with createAuthClient .

import { betterAuth } from "better-auth";

export const auth = betterAuth({ database: myDatabaseOrAdapter, // driver or adapter; omit for stateless mode emailAndPassword: { enabled: true }, socialProviders: { github: { clientId: process.env.GITHUB_CLIENT_ID as string, clientSecret: process.env.GITHUB_CLIENT_SECRET as string, }, }, });

Core setup checklist

• Export the instance as auth (or default export) so helpers find it.

• Keep BETTER_AUTH_URL in sync with the public base URL.

• Pass the full base URL to the client if you change the /api/auth base path.

• Add database migrations before enabling plugins that require tables.

Server API usage

• Call server endpoints via auth.api.* with { body, headers, query } .

• Use asResponse: true if you need a Response object.

• Use returnHeaders: true to access Set-Cookie headers.

import { auth } from "./auth";

const session = await auth.api.getSession({ headers: request.headers, });

const response = await auth.api.signInEmail({ body: { email, password }, asResponse: true, });

Session access

• Client: authClient.useSession() or authClient.getSession() .

• Server: auth.api.getSession({ headers }) .

TypeScript tips

• Infer types with auth.$Infer and authClient.$Infer .

• Use inferAdditionalFields on the client when you extend the user schema.

References

• toolchains/platforms/auth/better-auth/better-auth-core/references/setup-database.md

• toolchains/platforms/auth/better-auth/better-auth-core/references/client-server.md

• toolchains/platforms/auth/better-auth/better-auth-core/references/typescript.md