How do you add a product to cart with a custom price?

curl -X POST https://example.com/wp-json/cocart/v2/cart/add-item \
  -H "Content-Type: application/json" \
  -d '{
    "id": "129",
    "quantity": "1",
    "price": 24
  }'

This is the most simplest way of adding a product to the cart with a custom price.

The price is not changing, what am I doing wrong?

You may have restricted the product or all products from being able to add the product to cart with a custom price. Or you have set a salt key and have not passed it via the headers.

How do I add the salt key to the request?

Simply modify the request by adding the salt key to the header. Make sure that the header includes x-cocart-salt followed by your unique salt key.

curl -X POST https://example.com/wp-json/cocart/v2/cart/add-item \
  -H "Content-Type: application/json" \
  -H "x-cocart-salt: cbb03bc3fc55dc75d39b2f20cc5b6071" \
  -d '{
    "id": "129",
    "quantity": "1",
    "price": 24
  }'