Magento2.3 REST API – Get Order Entity ID from Increment ID

Its not mandatory that entity_id of sales_order table and increment_id of sales_order table are same.

entity_id field should be auto incremented ,so it may be differ when you delete any specific order manually and its used as foreign key in sales_order_item table to identify how many items each order have.

Meanwhile you must need to pass increment_id with orders api , But your url should be like this http://os.mydomain.com/index.php/rest/V1/orders/000000003

here 000000003 this is my increment_id

Then pass Authorization Bearer accesstoken in headers

It will works for all orders.

Use below tutorial for place order:

https://devdocs.magento.com/guides/v2.3/rest/tutorials/orders/order-create-order.html

You can directly use below request

POST http:///rest/default/V1/carts/mine/payment-information

for place order.

If you looking for online payment method then check this request in your browser console at payment page and pass required parameters. Generally magento suggest do not pass card detail to server instead pass token so you have to generate card token from your end pass into above rest api and for save card you have to pass public hash .