Better Auth Integration

Sync your Better Auth users to Sequenzy with a simple plugin. When users sign up, they’re automatically added as subscribers—enabling welcome emails, onboarding sequences, and more.

Installation

Install the official Sequenzy plugin for Better Auth:

npm install @sequenzy/better-auth
# or
bun add @sequenzy/better-auth
# or
pnpm add @sequenzy/better-auth

Quick Setup

1. Get Your API Key

Go to Settings → API Keys in Sequenzy
Click Create API Key
Copy the key and add it to your environment variables:

SEQUENZY_API_KEY=sk_live_xxxxxxxxxxxxx

2. Add the Plugin

Add the Sequenzy plugin to your Better Auth configuration:

auth.ts

import { betterAuth } from "better-auth";
import { sequenzy } from "@sequenzy/better-auth";

export const auth = betterAuth({
  // ... your existing config
  plugins: [
    sequenzy({
      apiKey: process.env.SEQUENZY_API_KEY!,
    }),
  ],
});

3. Add Client Plugin (Optional)

For TypeScript type inference, add the client plugin:

auth-client.ts

import { createAuthClient } from "better-auth/client";
import { sequenzyClient } from "@sequenzy/better-auth/client";

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

That’s it! New users will now be automatically synced to Sequenzy.

Configuration Options

sequenzy({
  // Required: Your Sequenzy API key
  apiKey: process.env.SEQUENZY_API_KEY!,

  // Optional: Add subscribers to specific lists only
  // Default: Uses your workspace default lists setting
  listIds: ["list_welcome", "list_newsletter"],

  // Optional: Tags to assign to new subscribers
  tags: ["signup", "better-auth"],

  // Optional: Enroll in automation sequences
  // Default: true
  enrollInSequences: true,

  // Optional: Extract custom attributes from the user
  getCustomAttributes: (user) => ({
    authProvider: "better-auth",
    signupDate: new Date().toISOString(),
  }),

  // Optional: Success callback
  onSubscriberCreated: ({ userId, email, subscriberId }) => {
    console.log(`Synced ${email} to Sequenzy`);
  },

  // Optional: Error callback
  onError: (error, user) => {
    console.error(`Failed to sync ${user.email}:`, error.message);
  },
});

What Gets Synced

When a user signs up through Better Auth, Sequenzy automatically:

Creates a new subscriber with their email
Syncs profile data (name parsed into first/last)
Adds to specified lists (or your workspace default lists if not specified)
Triggers any matching automations

Synced Attributes

Attribute	Source
`email`	User’s email address
`firstName`	First word of user’s name
`lastName`	Remaining words of user’s name
Custom attributes	Via `getCustomAttributes` option

List Assignment

Use Workspace Default Lists

By default, new subscribers use the default lists you choose in workspace settings:

sequenzy({
  apiKey: process.env.SEQUENZY_API_KEY!,
  // No listIds = workspace default lists
});

Add to Specific Lists

To add subscribers to specific lists only:

sequenzy({
  apiKey: process.env.SEQUENZY_API_KEY!,
  listIds: ["list_abc123", "list_def456"],
});

Add to No Lists

To create subscribers without list assignment:

sequenzy({
  apiKey: process.env.SEQUENZY_API_KEY!,
  listIds: [], // Empty array = no lists
});

Supported Auth Methods

The plugin hooks into these Better Auth flows:

Method	Endpoint	Synced
Email/Password	`/sign-up/email`	Yes
Google OAuth	`/callback/google`	Yes
GitHub OAuth	`/callback/github`	Yes
Other OAuth	`/callback/*`	Yes

Both new registrations and new OAuth sign-ups are synced. Returning OAuth users (already have an account) are not re-synced.

Using with Automations

Welcome Sequence

Create an automation to welcome every new user:

Go to Automations → Create New
Set trigger to Contact Added
Add your welcome email sequence
Activate the automation

Every Better Auth signup will now receive your welcome sequence.

Personalization

Use synced attributes in your emails:

Hi {{firstName}},

Welcome! We're excited to have you on board.

Error Handling

The plugin is non-blocking by design. If Sequenzy is unavailable:

Authentication succeeds normally
User account is created
Error is logged (if onError is set)

sequenzy({
  apiKey: process.env.SEQUENZY_API_KEY!,
  onError: (error, user) => {
    // Log to your error tracking service
    Sentry.captureException(error, {
      extra: { userEmail: user.email },
    });
  },
});

Custom Attributes

Add any data you want to track:

sequenzy({
  apiKey: process.env.SEQUENZY_API_KEY!,
  getCustomAttributes: (user) => ({
    userId: user.id,
    hasAvatar: !!user.image,
    signupSource: "web",
    signupTimestamp: Date.now(),
  }),
});

These attributes are available in:

Subscriber profiles
Email personalization
Segment filters
Automation conditions

Tagging Signups

Tag new subscribers for organization or automation triggers:

sequenzy({
  apiKey: process.env.SEQUENZY_API_KEY!,
  tags: ["signup", "better-auth", "web-app"],
});

You can then:

Filter subscribers by tag
Trigger automations on tag assignment
Create segments based on tags

FAQ

Does this sync existing users?

No, only new sign-ups after adding the plugin are synced. Existing users need to be imported separately via the API or CSV upload.

What if a user already exists in Sequenzy?

The plugin uses Sequenzy’s upsert API—existing subscribers get their attributes merged, not duplicated.

Can I disable automation enrollment?

Yes, set enrollInSequences: false to create subscribers without triggering automations.

Is the plugin blocking?

No. The plugin runs asynchronously after authentication succeeds. Auth flow is never delayed or blocked.

What if Sequenzy is down?

Authentication succeeds normally. The sync failure is logged via onError if provided.

Is this included in my plan?

Yes, the Better Auth integration is included at no extra cost.

Source Code

The plugin is open source:

GitHub Repository

View source, report issues, or contribute

​Installation

​Quick Setup

​1. Get Your API Key

​2. Add the Plugin

​3. Add Client Plugin (Optional)

​Configuration Options

​What Gets Synced

​Synced Attributes

​List Assignment

​Use Workspace Default Lists

​Add to Specific Lists

​Add to No Lists

​Supported Auth Methods

​Using with Automations

​Welcome Sequence

​Personalization

​Error Handling

​Custom Attributes

​Tagging Signups

​FAQ

​Source Code