Better Auth is a modern authentication library for TypeScript. This plugin integrates Commet directly into your Better Auth setup.

Features

Automatic customer creation on signup
Customer Portal for self-service billing management
Subscription management (get, cancel)
Feature access control (boolean, metered, seats)
Usage tracking for metered billing
Seat management for per-user pricing
Optional webhook handling with signature verification

Installation

pnpm add better-auth @commet/better-auth @commet/node

npm install better-auth @commet/better-auth @commet/node

yarn add better-auth @commet/better-auth @commet/node

bun add better-auth @commet/better-auth @commet/node

Preparation

Get your API key from the Commet dashboard. Use a key from a sandbox organization while you're integrating; switch to a live-org key when you go to production.

.env

COMMET_API_KEY=ck_...

Server Configuration

auth.ts

import { betterAuth } from "better-auth";
import {
  commet,
  portal,
  subscriptions,
  features,
  usage,
  seats,
} from "@commet/better-auth";
import { Commet } from "@commet/node";

const commetClient = new Commet({
  apiKey: process.env.COMMET_API_KEY,
  environment: process.env.COMMET_ENVIRONMENT, // 'sandbox' or 'production'
});

export const auth = betterAuth({
  // ... your config
  plugins: [
    commet({
      client: commetClient,
      createCustomerOnSignUp: true,
      use: [
        portal(),
        subscriptions(),
        features(),
        usage(),
        seats(),
      ],
    }),
  ],
});

Client Configuration

auth-client.ts

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

export const authClient = createAuthClient({
  plugins: [commetClient()],
});

Configuration Options

commet({
  client: commetClient,                    // Required: Commet SDK instance
  createCustomerOnSignUp: true,            // Auto-create customer on signup
  getCustomerCreateParams: ({ user }) => ({
    legalName: user.name,
    metadata: { source: "web" },
  }),
  use: [/* plugins */],
})

When createCustomerOnSignUp is enabled, a Commet customer is automatically created using the user's ID as the customerId. No database mapping required.

Portal Plugin

Redirects users to the Commet customer portal for self-service billing management.

Server

import { commet, portal } from "@commet/better-auth";

commet({
  client: commetClient,
  use: [
    portal({ returnUrl: "/dashboard" }),
  ],
})

Client

// Redirects to Commet customer portal
await authClient.customer.portal();

Subscriptions Plugin

Manage customer subscriptions.

Server

import { commet, subscriptions } from "@commet/better-auth";

commet({
  client: commetClient,
  use: [subscriptions()],
})

Client

// Get current subscription
const { data: subscription } = await authClient.subscription.get();

// Cancel subscription
await authClient.subscription.cancel({
  subscriptionId: "sub_xxx",
  reason: "Too expensive",
  immediate: false, // Cancel at period end
});

Features Plugin

Check feature access for the authenticated user.

Server

import { commet, features } from "@commet/better-auth";

commet({
  client: commetClient,
  use: [features()],
})

Client

// List all features
const { data: featuresList } = await authClient.features.list();

// Get specific feature
const { data: feature } = await authClient.features.get("api_calls");

// Check if feature is enabled (boolean)
const { data: check } = await authClient.features.check("sso");

// Check if user can use one more unit (metered)
const { data: canUse } = await authClient.features.canUse("api_calls");
// Returns: { allowed: boolean, willBeCharged: boolean }

Usage Plugin

Track usage events for metered billing.

Server

import { commet, usage } from "@commet/better-auth";

commet({
  client: commetClient,
  use: [usage()],
})

Client

await authClient.usage.track({
  feature: "api_calls",
  value: 1,
  idempotencyKey: `evt_${Date.now()}`
});

The authenticated user is automatically associated with the event.

Seats Plugin

Manage seat-based licenses.

Server

import { commet, seats } from "@commet/better-auth";

commet({
  client: commetClient,
  use: [seats()],
})

Client

// List all seat balances
const { data: seatBalances } = await authClient.seats.list();

// Add seats
await authClient.seats.add({ seatType: "member", count: 5 });

// Remove seats
await authClient.seats.remove({ seatType: "member", count: 2 });

// Set exact count
await authClient.seats.set({ seatType: "admin", count: 3 });

// Set all seat types at once
await authClient.seats.setAll({ admin: 2, member: 10, viewer: 50 });

Webhooks Plugin

Handle Commet webhooks. This is optional since you can always query state directly.

Server

import { commet, webhooks } from "@commet/better-auth";

commet({
  client: commetClient,
  use: [
    webhooks({
      secret: process.env.COMMET_WEBHOOK_SECRET,
      onPayload: (payload) => {
        // Catch-all handler
      },
      onSubscriptionCreated: (payload) => {},
      onSubscriptionActivated: (payload) => {},
      onSubscriptionCanceled: (payload) => {},
      onSubscriptionUpdated: (payload) => {},
    }),
  ],
})

Configure the webhook endpoint in your Commet dashboard: /api/auth/commet/webhooks

Full Example

Server Setup

auth.ts

import { betterAuth } from "better-auth";
import { drizzleAdapter } from "better-auth/adapters/drizzle";
import {
  commet as commetPlugin,
  portal,
  subscriptions,
  features,
  usage,
  seats,
} from "@commet/better-auth";
import { Commet } from "@commet/node";
import { db } from "./db";
import * as schema from "./schema";

const commetClient = new Commet({
  apiKey: process.env.COMMET_API_KEY!,
  environment: process.env.COMMET_ENVIRONMENT as "sandbox" | "production",
});

export const auth = betterAuth({
  database: drizzleAdapter(db, { provider: "pg", schema }),
  emailAndPassword: { enabled: true },
  plugins: [
    commetPlugin({
      client: commetClient,
      createCustomerOnSignUp: true,
      getCustomerCreateParams: ({ user }) => ({
        legalName: user.name,
      }),
      use: [
        portal({ returnUrl: "/dashboard" }),
        subscriptions(),
        features(),
        usage(),
        seats(),
      ],
    }),
  ],
});

Client Setup

auth-client.ts

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

export const authClient = createAuthClient({
  baseURL: process.env.NEXT_PUBLIC_BETTER_AUTH_URL,
  plugins: [commetClient()],
});

export const { signIn, signUp, signOut, useSession } = authClient;

Usage in Components

dashboard.tsx

"use client";

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

export function BillingSection() {
  const handlePortal = async () => {
    await authClient.customer.portal();
  };

  const checkFeature = async () => {
    const { data } = await authClient.features.canUse("api_calls");
    if (data?.allowed) {
      // Proceed with action
      await authClient.usage.track({ feature: "api_calls" });
    }
  };

  return (
    <div>
      <button onClick={handlePortal}>Manage Billing</button>
      <button onClick={checkFeature}>Use Feature</button>
    </div>
  );
}

Better Auth is a modern authentication library for TypeScript. This plugin integrates Commet directly into your Better Auth setup.

Features

Automatic customer creation on signup
Customer Portal for self-service billing management
Subscription management (get, cancel)
Feature access control (boolean, metered, seats)
Usage tracking for metered billing
Seat management for per-user pricing
Optional webhook handling with signature verification

Installation

pnpm add better-auth @commet/better-auth @commet/node

npm install better-auth @commet/better-auth @commet/node

yarn add better-auth @commet/better-auth @commet/node

bun add better-auth @commet/better-auth @commet/node

Preparation

Get your API key from the Commet dashboard. Use a key from a sandbox organization while you're integrating; switch to a live-org key when you go to production.

.env

COMMET_API_KEY=ck_...

Server Configuration

auth.ts

import { betterAuth } from "better-auth";
import {
  commet,
  portal,
  subscriptions,
  features,
  usage,
  seats,
} from "@commet/better-auth";
import { Commet } from "@commet/node";

const commetClient = new Commet({
  apiKey: process.env.COMMET_API_KEY,
  environment: process.env.COMMET_ENVIRONMENT, // 'sandbox' or 'production'
});

export const auth = betterAuth({
  // ... your config
  plugins: [
    commet({
      client: commetClient,
      createCustomerOnSignUp: true,
      use: [
        portal(),
        subscriptions(),
        features(),
        usage(),
        seats(),
      ],
    }),
  ],
});

Client Configuration

auth-client.ts

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

export const authClient = createAuthClient({
  plugins: [commetClient()],
});

Configuration Options

commet({
  client: commetClient,                    // Required: Commet SDK instance
  createCustomerOnSignUp: true,            // Auto-create customer on signup
  getCustomerCreateParams: ({ user }) => ({
    legalName: user.name,
    metadata: { source: "web" },
  }),
  use: [/* plugins */],
})

When createCustomerOnSignUp is enabled, a Commet customer is automatically created using the user's ID as the customerId. No database mapping required.

Portal Plugin

Redirects users to the Commet customer portal for self-service billing management.

Server

import { commet, portal } from "@commet/better-auth";

commet({
  client: commetClient,
  use: [
    portal({ returnUrl: "/dashboard" }),
  ],
})

Client

// Redirects to Commet customer portal
await authClient.customer.portal();

Subscriptions Plugin

Manage customer subscriptions.

Server

import { commet, subscriptions } from "@commet/better-auth";

commet({
  client: commetClient,
  use: [subscriptions()],
})

Client

// Get current subscription
const { data: subscription } = await authClient.subscription.get();

// Cancel subscription
await authClient.subscription.cancel({
  subscriptionId: "sub_xxx",
  reason: "Too expensive",
  immediate: false, // Cancel at period end
});

Features Plugin

Check feature access for the authenticated user.

Server

import { commet, features } from "@commet/better-auth";

commet({
  client: commetClient,
  use: [features()],
})

Client

// List all features
const { data: featuresList } = await authClient.features.list();

// Get specific feature
const { data: feature } = await authClient.features.get("api_calls");

// Check if feature is enabled (boolean)
const { data: check } = await authClient.features.check("sso");

// Check if user can use one more unit (metered)
const { data: canUse } = await authClient.features.canUse("api_calls");
// Returns: { allowed: boolean, willBeCharged: boolean }

Usage Plugin

Track usage events for metered billing.

Server

import { commet, usage } from "@commet/better-auth";

commet({
  client: commetClient,
  use: [usage()],
})

Client

await authClient.usage.track({
  feature: "api_calls",
  value: 1,
  idempotencyKey: `evt_${Date.now()}`
});

The authenticated user is automatically associated with the event.

Seats Plugin

Manage seat-based licenses.

Server

import { commet, seats } from "@commet/better-auth";

commet({
  client: commetClient,
  use: [seats()],
})

Client

// List all seat balances
const { data: seatBalances } = await authClient.seats.list();

// Add seats
await authClient.seats.add({ seatType: "member", count: 5 });

// Remove seats
await authClient.seats.remove({ seatType: "member", count: 2 });

// Set exact count
await authClient.seats.set({ seatType: "admin", count: 3 });

// Set all seat types at once
await authClient.seats.setAll({ admin: 2, member: 10, viewer: 50 });

Webhooks Plugin

Handle Commet webhooks. This is optional since you can always query state directly.

Server

import { commet, webhooks } from "@commet/better-auth";

commet({
  client: commetClient,
  use: [
    webhooks({
      secret: process.env.COMMET_WEBHOOK_SECRET,
      onPayload: (payload) => {
        // Catch-all handler
      },
      onSubscriptionCreated: (payload) => {},
      onSubscriptionActivated: (payload) => {},
      onSubscriptionCanceled: (payload) => {},
      onSubscriptionUpdated: (payload) => {},
    }),
  ],
})

Configure the webhook endpoint in your Commet dashboard: /api/auth/commet/webhooks

Full Example

Server Setup

auth.ts

import { betterAuth } from "better-auth";
import { drizzleAdapter } from "better-auth/adapters/drizzle";
import {
  commet as commetPlugin,
  portal,
  subscriptions,
  features,
  usage,
  seats,
} from "@commet/better-auth";
import { Commet } from "@commet/node";
import { db } from "./db";
import * as schema from "./schema";

const commetClient = new Commet({
  apiKey: process.env.COMMET_API_KEY!,
  environment: process.env.COMMET_ENVIRONMENT as "sandbox" | "production",
});

export const auth = betterAuth({
  database: drizzleAdapter(db, { provider: "pg", schema }),
  emailAndPassword: { enabled: true },
  plugins: [
    commetPlugin({
      client: commetClient,
      createCustomerOnSignUp: true,
      getCustomerCreateParams: ({ user }) => ({
        legalName: user.name,
      }),
      use: [
        portal({ returnUrl: "/dashboard" }),
        subscriptions(),
        features(),
        usage(),
        seats(),
      ],
    }),
  ],
});

Client Setup

auth-client.ts

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

export const authClient = createAuthClient({
  baseURL: process.env.NEXT_PUBLIC_BETTER_AUTH_URL,
  plugins: [commetClient()],
});

export const { signIn, signUp, signOut, useSession } = authClient;

Usage in Components

dashboard.tsx

"use client";

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

export function BillingSection() {
  const handlePortal = async () => {
    await authClient.customer.portal();
  };

  const checkFeature = async () => {
    const { data } = await authClient.features.canUse("api_calls");
    if (data?.allowed) {
      // Proceed with action
      await authClient.usage.track({ feature: "api_calls" });
    }
  };

  return (
    <div>
      <button onClick={handlePortal}>Manage Billing</button>
      <button onClick={checkFeature}>Use Feature</button>
    </div>
  );
}

Better Auth

Features

Installation

Preparation

Server Configuration

Client Configuration

Configuration Options

Portal Plugin

Subscriptions Plugin

Features Plugin

Usage Plugin

Seats Plugin

Webhooks Plugin

Full Example

Server Setup

Client Setup

Usage in Components

On this page

Better Auth

Features

Installation

Preparation

Server Configuration

Client Configuration

Configuration Options

Portal Plugin

Subscriptions Plugin

Features Plugin

Usage Plugin

Seats Plugin

Webhooks Plugin

Full Example

Server Setup

Client Setup

Usage in Components

On this page