BoxDB database adapter for Better Auth

A direct adapter for Better Auth 1.7.x. Install @boxdb/client, @boxdb/better-auth-adapter, and better-auth.

npm install @boxdb/client @boxdb/better-auth-adapter better-auth

import { BoxDB } from "@boxdb/client";
import { betterAuth } from "better-auth";
import { betterAuthAdapter } from "@boxdb/better-auth-adapter";

const client = await BoxDB.open("auth.db");
export const auth = betterAuth({
  database: betterAuthAdapter(client),
  secret: process.env.BETTER_AUTH_SECRET,
  baseURL: process.env.BETTER_AUTH_URL,
  emailAndPassword: { enabled: true },
});
// Close client when the application shuts down.

The adapter uses Better Auth's factory for model/field mappings, IDs, dates, booleans, JSON and arrays. Set usePlural or debugLogs in the adapter's second argument when needed. Both generated string IDs and serial numeric IDs work. Better Auth transaction callbacks use explicit BoxDB transactions internally. Native single-statement consumeOne and incrementOne preserve atomicity under concurrent requests.

Use Better Auth's schema generation command, or generate SQL directly:

const options = { emailAndPassword: { enabled: true } };
const adapter = betterAuthAdapter(client)(options);
const schema = await adapter.createSchema!(options);
await client.exec(schema.code); // Initial schema creation, once.

Generation creates an initial schema; it does not diff or migrate existing schemas. Review generated SQL before applying plugin/schema changes. Better Auth handles relation fetching through its adapter-factory fallback. Integer numeric fields must fit JavaScript's safe range; booleans are mapped from bigint storage results. The adapter borrows the client and never closes it.