Mastercard OAuth 1.0a Integration

Job ID: 39943806

Budget: $30 – $250 USD

I need a working OAuth 1.0a flow wired into my existing web application so it can talk to the Mastercard APIs behind their secure gateway. The site is already up and running; I’ll share the tech stack and credentials after we start.

Scope for this first phase is intentionally lean:
• Add the OAuth 1.0a signing logic (consumer key, secret, RSA-SHA1 signature, nonce, timestamp, base string).
• Handle request token, user redirect/authorization, and access-token exchange.
• Demonstrate a single successful call to one protected Mastercard endpoint (I’ll specify which once NDA is signed).
• Supply concise setup notes so I can reproduce the flow locally.

Please keep external libraries to a minimum, comment the code clearly, and flag any prerequisites. Prior experience with Mastercard Sandbox, payment gateways, or similar OAuth 1.0a–secured APIs is a plus.