Mono Connect.js

Link financial accounts or start payment flows with the Connect.js browser SDK.

Connect.js opens Mono’s hosted Connect widget inside your web application. The widget handles institution selection, credentials, multi-factor authentication, account selection, and flow events. Your application controls when the widget opens and what happens after it succeeds.

This independent guide reflects @mono.co/connect.js 2.2.0. For production decisions, use Mono’s official financial data documentation and the Connect.js source.

Choose a flow

Link an account

Open the widget, receive an auth code, and exchange it for an account ID on your backend.

Reauthorize an account

Reconnect a previously linked account by passing its Mono account ID to reauthorise().

Start a payment flow

Configure the widget with the payments scope and payment data.

Use a framework

Follow browser-lifecycle examples for React, Angular, and Next.js.

Install

npm install @mono.co/connect.js

The package README lists Node.js 10 or later as its minimum requirement.

Minimal account-linking example

The account-linking path requires a public key, auth scope, customer data, and a success callback. Call setup() before open().

import Connect from "@mono.co/connect.js"

const connect = new Connect({
  key: "PUBLIC_KEY",
  scope: "auth",
  data: {
    customer: {
      name: "Ada Lovelace",
      email: "[e-mail]"
    }
  },
  onSuccess: ({ code }) => {
    // Send the short-lived code to your backend.
    fetch("/api/mono/exchange", {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({ code })
    })
  },
  onClose: () => console.log("Connect closed")
})

connect.setup()

document
  .querySelector("#link-account")
  .addEventListener("click", () => connect.open())

Keep the trust boundary clear

Runs in the browser	Runs on your backend
Public key	Mono secret key
Connect.js widget	Auth-code exchange
Customer input passed to the widget	Account ID storage
onSuccess receives a short-lived code	Mono API requests for account data

Never place MONO_SECRET_KEY in browser code, a public environment variable, or the Connect configuration. Send the auth code to your backend and exchange it there.

SDK lifecycle

create Connect instance
        ↓
setup() or reauthorise(accountId)
        ↓
open()
        ↓
onEvent(eventName, data)
        ↓
onSuccess(result) or onClose()

For a copy-paste implementation including the backend exchange, continue to the Quickstart. For compact facts intended for humans and agents, use the Integration contract.

Version and evidence

See Source and scope for the exact package version, source commit, verification date, and precedence rules used by this guide.