Senior Web Application & Checkout Flow Engineer

Project Overview We are looking for an experienced web application engineer who specializes in complex e-commerce checkout flows, payment integrations, browser behavior, and purchasing automation. We are experiencing a checkout issue where selecting a specific payment method causes the authorization window to open but never successfully redirects to the payment provider. Instead, the checkout ultimately fails. We need someone who can diagnose the root cause and provide a reliable solution or workaround. What We Need We are looking for someone who has deep experience with: Browser DevTools Network analysis (HAR files) JavaScript debugging Payment gateway integrations Checkout workflows Browser security policies Popups and redirect handling Session/token management OAuth and cross-site authentication GraphQL APIs Reverse engineering web applications Browser automation (Playwright, Puppeteer, Selenium) Chrome debugging protocol Current Symptoms The payment flow behaves as follows: Checkout loads normally. Selecting one payment option opens a popup window. The popup remains on about:blank. The checkout eventually redirects to a generic payment failure page. Network requests complete successfully (HTTP 200), but the payment authorization never starts. No obvious JavaScript errors are displayed. We have: Console logs Network traces HAR files Request payloads Screenshots Browser debugging information These will all be provided. Deliverables We are looking for someone who can: Analyze the complete checkout flow. Determine exactly where the process is failing. Explain why the payment authorization never begins. Identify whether the issue is browser-related, session-related, payment-provider-related, or application-related. Recommend a reliable solution or workaround. If possible, implement or demonstrate the fix. Ideal Experience We're looking for someone who has worked with technologies such as: Stripe Adyen PayPal Bolt Checkout Braintree Checkout.com CyberSource Worldpay as well as: Cloudflare Akamai Browser fingerprinting Anti-bot systems Session management Modern web security Requirements Please include: Examples of similar checkout or payment-flow debugging projects you've completed. Your experience troubleshooting payment redirects and browser-based purchasing workflows. Your availability. Estimated hours required to diagnose the issue.