Better Auth: key to solve authentication Problems

Installation & Quick Setup

Prerequisites

Before you begin, make sure you have:

• Node.js 20+ (to use the latest libraries).
  
  

• A Dodo Payments account with your API keys on hand (you’ll need the secret key and to set up webhook secrets).
  
  

• An existing project using Better Auth (or at least the Better Auth core installed).

You’ll also need to generate a Better Auth secret key (via the Better Auth CLI or docs) and set it in your environment. Better Auth requires a couple of env vars, for example:

BETTER_AUTH_SECRET=your-better-auth-secret

BETTER_AUTH_URL=http://localhost:3000

Better Auth auto-detects these, so once they’re in your .env you don’t have to reference them in code. (And as always, never commit secrets – use .env or a secret manager.)

Install packages

Run the following in your project root to install the Dodo Payments adapter and its deps:

npm install @dodopayments/better-auth dodopayments better-auth zod

This pulls in:

• @dodopayments/better-auth (the Better Auth plugin),
  
  

• dodopayments (the Dodo Payments SDK),
  
  

• better-auth (if not already installed),
  
  

• zod (for schemas).

Dodo Payments’ docs confirm this setup step.

Environment variables

Add the following to your .env (or equivalent) file:

DODO_PAYMENTS_API_KEY=your_api_key_here

DODO_PAYMENTS_WEBHOOK_SECRET=your_webhook_secret_here

BETTER_AUTH_URL=http://localhost:3000

BETTER_AUTH_SECRET=your_better_auth_secret_here

The first two are for Dodo Payments: your API key (used by the SDK client) and the webhook secret (used to verify incoming webhooks). The last two are for Better Auth itself (its base URL and secret). As noted, never commit these values to version control. The Better Auth docs also show setting these variables in .env.

Server-Side Integration (Core Wiring)

On the server, you need to wire up Better Auth with the Dodo Payments plugin. In a file like src/lib/auth.ts (or wherever you configure Better Auth), do something like this:

import { BetterAuth } from "better-auth";

import { dodopayments, checkout, portal, webhooks, usage } from "@dodopayments/better-auth";

import DodoPayments from "dodopayments";

const dodoPayments = new DodoPayments({

  bearerToken: process.env.DODO_PAYMENTS_API_KEY!,

  environment: "test_mode",  // use "live_mode" in production

});

export const { auth, endpoints, client } = BetterAuth({

  plugins: [

    dodopayments({

      client: dodoPayments,

      createCustomerOnSignUp: true,

      use: [

        checkout({

          products: [{ productId: "pdt_xxx", slug: "premium-plan" }],

          successUrl: "/dashboard/success",

          authenticatedUsersOnly: true,

        }),

        portal(),

        webhooks({

          webhookKey: process.env.DODO_PAYMENTS_WEBHOOK_SECRET!,

          // you can also specify onPaymentSucceeded, onPaymentFailed, etc.

          onPayload: async (payload) => {

            console.log("Received Dodo webhook:", payload.event_type);

          },

        }),

        usage(),

      ],

    }),

  ],

});

Here’s what this does:

• We create a DodoPayments client with your API key. (Note: use "test_mode" locally and switch to "live_mode" in production.)
  
  

• In BetterAuth({...}), we include one plugin: dodopayments({...}).
  
  

• We pass in the client, enable createCustomerOnSignUp, and list our sub-plugins in use: [...].
  
  

• The checkout() plugin maps product IDs to slugs (so you can use friendly slugs in code), plus a redirect URL.
  
  

• The portal() plugin enables the customer portal.
  
  

• The webhooks() plugin takes your webhook secret and handlers.
  
  

• The usage() plugin enables usage ingestion endpoints.

This example is a minimal wiring. You can expand it with more products, custom webhook event handlers, etc. (The official docs have a similar sample.) Remember to keep your environment in test_mode while developing, then flip to "live_mode" when you go live.

Client-Side Setup

In your frontend (e.g. React, Next.js, etc.), set up the Better Auth client and include Dodo Payments’ client plugin. For example, in src/lib/auth-client.ts:

import { createAuthClient } from "better-auth/react";

import { dodopaymentsClient } from "@dodopayments/better-auth";

export const authClient = createAuthClient({

  baseURL: process.env.BETTER_AUTH_URL || "http://localhost:3000",

  plugins: [dodopaymentsClient()],

});

This gives you authClient.dodopayments.* methods on the client. (Make sure BETTER_AUTH_URL is set to your API base, like http://localhost:3000.) Now you can call the Dodo Payments-related methods from your UI and they’ll hit your server’s Better Auth endpoints.