title: Is it possible and allowed to use custom (own) PayPal button with Express Checkout and REST API?
body: <p>I have implemented PayPal rest integration, and now I can create payments. So I have to enable payments approval now. I used this documentation: </p>
  
  <p><a href="https://developer.paypal.com/docs/integration/web/accept-paypal-payment/" rel="noreferrer">https://developer.paypal.com/docs/integration/web/accept-paypal-payment/</a> </p>
  
  <p>As I can see, usage of <code>approval_url</code> i a legacy method (it opens approval page in a separate tab). But a modern one, described here: </p>
  
  <p><a href="https://developer.paypal.com/docs/integration/direct/express-checkout/integration-jsv4/advanced-integration/#set-up-your-client" rel="noreferrer">https://developer.paypal.com/docs/integration/direct/express-checkout/integration-jsv4/advanced-integration/#set-up-your-client</a></p>
  
  <p>does require to render PayPal button using <code>checkout.js</code> library script. I want to use my own button, but don't know what to call to perform payment approval. And I don's know if it is allowed at all. Can not find the good answer anywhere. Please help.</p>