Updating Existing Ecommerce Website Built in ReactJs, NodeJs, ExpressJs and MongoDb

I need Expert ReactJs, NodeJs, Express and MongoDB Developer want to integrate Paytm Payment Gateway into my website. want to do it tomorrow end of the day and it's an urgent requirement. In Storefront I am using react-router for routing. if you know ReactJs and express well than bid this project. The logic for implement: The checksum will be generated on the API server (ExpressJs). From storefront (ReactJs) we will be passing required parameter to API server and it will return Checksumhash, and with all required parameters with checksum hash we will be redirecting it to payment gateway URL and from payment gateway, we will getting success response. We have to fetch that success response from storefront (ReactJs) and Process the order by requesting API Server and So on. Go down to the paytm payment gateway developers documentation for the better understanding of the flow of paytm. I want Quick Turnaround time this job is hardly of 2 hours I will explain the whole flow. You just have to write the javascript that's It.