Better Auth Plugin

Overview

The Better Auth plugin provides first-class integration between Autumn and Better Auth, a modern authentication library for TypeScript. It automatically handles customer identification based on your Better Auth session and organization context.

Installation

Install both Autumn and Better Auth:

npm install autumn-js better-auth

Quick Start

Server Setup

Add the Autumn plugin to your Better Auth configuration:

lib/auth.ts

import { betterAuth } from "better-auth";
import { autumn } from "autumn-js/better-auth";

export const auth = betterAuth({
  database: {
    // Your database config
  },
  plugins: [
    autumn({
      secretKey: process.env.AUTUMN_SECRET_KEY,
    }),
  ],
});

Client Setup

Add the Autumn client plugin:

lib/auth-client.ts

import { createAuthClient } from "better-auth/client";
import { autumnClient } from "autumn-js/better-auth/client";

export const authClient = createAuthClient({
  baseURL: "http://localhost:3000",
  plugins: [autumnClient()],
});

That’s it! Autumn endpoints are now available on your auth client.

Configuration

Plugin Options

string

default:"process.env.AUTUMN_SECRET_KEY"

Your Autumn API secret key. Defaults to the AUTUMN_SECRET_KEY environment variable.

string

default:"https://api.useautumn.com/v1"

The Autumn API base URL. Only change this if you’re self-hosting Autumn.

CustomerScope

default:"user"

How to resolve customer identity from the session. Options:

"user" - Use the authenticated user as the customer
"organization" - Use the active organization as the customer
"user_and_organization" - Prefer organization, fall back to user

IdentifyFn

Custom identity resolver function. Overrides customerScope for advanced use cases.

Customer Scope Modes

User Scope (Default)

Customers are identified by user ID:

autumn({
  customerScope: "user",
})

Organization Scope

Customers are identified by organization ID (requires Better Auth organization plugin):

import { betterAuth } from "better-auth";
import { organization } from "better-auth/plugins";
import { autumn } from "autumn-js/better-auth";

export const auth = betterAuth({
  plugins: [
    organization(),
    autumn({
      customerScope: "organization",
    }),
  ],
});

User and Organization Scope

Prefer organization if active, otherwise use user:

autumn({
  customerScope: "user_and_organization",
})

Custom Identity Resolution

For advanced scenarios, provide a custom identify function:

autumn({
  identify: ({ session, organization }) => {
    // Use organization for business accounts
    if (organization) {
      return {
        customerId: organization.id,
        customerData: {
          name: organization.name,
        },
      };
    }
    
    // Use user for personal accounts
    if (session?.user) {
      return {
        customerId: session.user.id,
        customerData: {
          name: session.user.name,
          email: session.user.email,
        },
      };
    }
    
    return null;
  },
})

Client Usage

Calling Autumn Endpoints

Use the auth client to call Autumn endpoints:

import { authClient } from "@/lib/auth-client";

// Get or create customer
const customer = await authClient.autumn.getOrCreateCustomer({
  body: {
    expand: ["balances.feature"],
  },
});

// List available plans
const plans = await authClient.autumn.listPlans({
  body: {},
});

// Attach a plan to the customer
const result = await authClient.autumn.attach({
  body: {
    planId: "plan_123",
  },
});

// Open customer portal
const portal = await authClient.autumn.openCustomerPortal({
  body: {
    returnUrl: window.location.href,
  },
});

Available Endpoints

All Autumn endpoints are available under authClient.autumn.*:

Customer Endpoints

// Get or create customer
await authClient.autumn.getOrCreateCustomer({ body: {} });

Billing Endpoints

// Attach a plan
await authClient.autumn.attach({ body: { planId: "plan_123" } });

// Preview attach
await authClient.autumn.previewAttach({ body: { planId: "plan_123" } });

// Update subscription
await authClient.autumn.updateSubscription({ body: { /* ... */ } });

// Preview update
await authClient.autumn.previewUpdateSubscription({ body: { /* ... */ } });

// Open customer portal
await authClient.autumn.openCustomerPortal({ body: { returnUrl: "/" } });

// Multi-attach plans
await authClient.autumn.multiAttach({ body: { plans: [/* ... */] } });

// Preview multi-attach
await authClient.autumn.previewMultiAttach({ body: { plans: [/* ... */] } });

// Setup payment method
await authClient.autumn.setupPayment({ body: {} });

Plan Endpoints

// List plans
await authClient.autumn.listPlans({ body: {} });

Event Endpoints

// List events
await authClient.autumn.listEvents({ body: {} });

// Aggregate events
await authClient.autumn.aggregateEvents({ body: { /* ... */ } });

Referral Endpoints

// Create referral code
await authClient.autumn.createReferralCode({ body: {} });

// Redeem referral code
await authClient.autumn.redeemReferralCode({ body: { code: "REF123" } });

React Integration

Use Autumn with Better Auth React hooks:

components/billing/PlanSelector.tsx

import { authClient } from "@/lib/auth-client";
import { useState, useEffect } from "react";

export function PlanSelector() {
  const [plans, setPlans] = useState([]);
  const [loading, setLoading] = useState(true);
  
  useEffect(() => {
    async function loadPlans() {
      try {
        const result = await authClient.autumn.listPlans({ body: {} });
        setPlans(result.data?.plans || []);
      } catch (error) {
        console.error("Failed to load plans", error);
      } finally {
        setLoading(false);
      }
    }
    
    loadPlans();
  }, []);
  
  const handleAttach = async (planId: string) => {
    try {
      await authClient.autumn.attach({ body: { planId } });
      alert("Plan attached successfully!");
    } catch (error) {
      console.error("Failed to attach plan", error);
    }
  };
  
  if (loading) return <div>Loading...</div>;
  
  return (
    <div>
      {plans.map((plan) => (
        <div key={plan.id}>
          <h3>{plan.name}</h3>
          <button onClick={() => handleAttach(plan.id)}>
            Subscribe
          </button>
        </div>
      ))}
    </div>
  );
}

Server-Side Usage

Access Autumn endpoints server-side using Better Auth’s server methods:

app/api/billing/route.ts

import { auth } from "@/lib/auth";
import { NextResponse } from "next/server";

export async function GET(request: Request) {
  // Get session from Better Auth
  const session = await auth.api.getSession({
    headers: request.headers,
  });
  
  if (!session) {
    return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
  }
  
  // Call Autumn endpoint
  const result = await auth.api.autumn.getOrCreateCustomer({
    body: { expand: ["balances.feature"] },
    headers: request.headers,
  });
  
  return NextResponse.json(result);
}

Organization Support

When using Better Auth’s organization plugin:

lib/auth.ts

import { betterAuth } from "better-auth";
import { organization } from "better-auth/plugins";
import { autumn } from "autumn-js/better-auth";

export const auth = betterAuth({
  plugins: [
    organization(),
    autumn({
      // Use organization as customer when active
      customerScope: "organization",
    }),
  ],
});

Now Autumn will:

Use the active organization as the customer when one is selected
Use organization name for customer data
Return null for customer when no organization is active

TypeScript Support

The plugin provides full TypeScript support:

import type { AutumnOptions } from "autumn-js/better-auth";

const options: AutumnOptions = {
  secretKey: process.env.AUTUMN_SECRET_KEY,
  customerScope: "user",
  identify: ({ session, organization }) => {
    // Fully typed session and organization
    if (organization) {
      return {
        customerId: organization.id,
        customerData: { name: organization.name },
      };
    }
    
    if (session?.user) {
      return {
        customerId: session.user.id,
        customerData: {
          name: session.user.name,
          email: session.user.email,
        },
      };
    }
    
    return null;
  },
};

How It Works

Session Resolution - Better Auth provides the current session
Organization Resolution - If using organizations, gets the active organization
Identity Resolution - Resolves customer identity based on customerScope or custom identify function
Endpoint Routing - Routes requests to appropriate Autumn API endpoints
Response Handling - Returns typed responses to your client

Error Handling

The plugin handles authentication errors:

try {
  const result = await authClient.autumn.attach({ body: { planId: "plan_123" } });
} catch (error) {
  if (error.status === 401) {
    // User not authenticated
    console.error("Please sign in");
  } else if (error.status === 404) {
    // Plan not found
    console.error("Invalid plan ID");
  } else {
    console.error("Unexpected error", error);
  }
}

Environment Variables

.env

# Required: Your Autumn secret key
AUTUMN_SECRET_KEY=sk_...

# Optional: Custom Autumn API URL (for self-hosted instances)
AUTUMN_BASE_URL=https://api.useautumn.com/v1

Complete Example

Here’s a full example with organizations:

lib/auth.ts

import { betterAuth } from "better-auth";
import { organization } from "better-auth/plugins";
import { autumn } from "autumn-js/better-auth";

export const auth = betterAuth({
  database: {
    provider: "postgres",
    url: process.env.DATABASE_URL!,
  },
  plugins: [
    organization(),
    autumn({
      secretKey: process.env.AUTUMN_SECRET_KEY,
      customerScope: "user_and_organization",
    }),
  ],
});

lib/auth-client.ts

import { createAuthClient } from "better-auth/client";
import { organizationClient } from "better-auth/client/plugins";
import { autumnClient } from "autumn-js/better-auth/client";

export const authClient = createAuthClient({
  baseURL: "http://localhost:3000",
  plugins: [
    organizationClient(),
    autumnClient(),
  ],
});

components/Billing.tsx

import { authClient } from "@/lib/auth-client";

export function Billing() {
  const openPortal = async () => {
    const result = await authClient.autumn.openCustomerPortal({
      body: { returnUrl: window.location.href },
    });
    
    if (result.data?.url) {
      window.location.href = result.data.url;
    }
  };
  
  return (
    <button onClick={openPortal}>
      Manage Billing
    </button>
  );
}

Next Steps

Hono Adapter

Use Autumn with Hono web framework

Next.js Adapter

Integrate Autumn with Next.js App Router

React Hooks

Build billing UIs with React hooks

API Reference

Explore all available API endpoints

JavaScript/TypeScript

Python

Framework Adapters

Better Auth Plugin

Overview

Installation

Quick Start

Server Setup

Client Setup

Configuration

Plugin Options

Customer Scope Modes

User Scope (Default)

Organization Scope

User and Organization Scope

Custom Identity Resolution

Client Usage

Calling Autumn Endpoints

Available Endpoints

Customer Endpoints

Billing Endpoints

Plan Endpoints

Event Endpoints

Referral Endpoints

React Integration

Server-Side Usage

Organization Support

TypeScript Support

How It Works

Error Handling

Environment Variables

Complete Example

Next Steps

Hono Adapter

Next.js Adapter

React Hooks

API Reference

​Overview

​Installation

​Quick Start

​Server Setup

​Client Setup

​Configuration

​Plugin Options

​Customer Scope Modes

​User Scope (Default)

​Organization Scope

​User and Organization Scope

​Custom Identity Resolution

​Client Usage

​Calling Autumn Endpoints

​Available Endpoints

​Customer Endpoints

​Billing Endpoints

​Plan Endpoints

​Event Endpoints

​Referral Endpoints

​React Integration

​Server-Side Usage

​Organization Support

​TypeScript Support

​How It Works

​Error Handling

​Environment Variables

​Complete Example

​Next Steps

Hono Adapter

Next.js Adapter

React Hooks

API Reference

Overview

Installation

Quick Start

Server Setup

Client Setup

Configuration

Plugin Options

Customer Scope Modes

User Scope (Default)

Organization Scope

User and Organization Scope

Custom Identity Resolution

Client Usage

Calling Autumn Endpoints

Available Endpoints

Customer Endpoints

Billing Endpoints

Plan Endpoints

Event Endpoints

Referral Endpoints

React Integration

Server-Side Usage

Organization Support

TypeScript Support

How It Works

Error Handling

Environment Variables

Complete Example

Next Steps