> ## Documentation Index
> Fetch the complete documentation index at: https://developer.transactbridge.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Overview

Integrate Transact Bridge and Retain Seamlessly with checkout.js

**Checkout.js** is a lightweight JavaScript library designed for effortless one-time and subscription billing integration.

With **Checkout.js**, you can:

* Open dynamic checkouts with prefilled customer details
* Build pricing pages with localized taxes and discounts applied automatically
* Interact with checkouts in real time and display relevant information on your page
* Create smooth upgrade workflows using inline checkouts
* Reduce churn effortlessly by integrating with Retain
* Enhance your payment experience with a simple yet powerful solution.

<Note>
  **Checkout.js** seamlessly embeds a payment widget as an iframe on partner
  websites, enabling customers to pay without leaving the page.
</Note>

<Card title="Check Demo flow" icon="desktop" href="https://www.transactbridge.com/demo">
  View the checkout.js rendering as a widget on our Demo Page.
</Card>