Postman was great until we needed to Test Real Payment Flows
Testing a payments product is far from straightforward. Payments are not just API calls and responses; they involve complex user journeys, external redirections, multi-step authentication, and multiple payment methods. As our product scaled, testing these flows reliably became more difficult, and our existing tools couldn't keep up.
We started with Postman for API testing, which helped validate basic scenarios in the early stages. But as we introduced more front-end interactivity and supported multiple payment connectors, Postman hit its limits. We needed a framework that could test the full user experience, handle authentication flows, and scale with our growing product.
We evaluated several alternatives, including Selenium, and eventually chose Cypress as our front-end and end-to-end testing framework. This post outlines the challenges we faced, why Postman and Selenium didn’t work for us, and how Cypress helped us build a more scalable and reliable testing strategy.
Testing payments is different from typical web applications. Real-world complexity introduces several unique challenges:
Many payment flows require 3D Secure (3DS), OTP verification, or redirects to banking pages. Postman, being limited to backend API testing, could not simulate these flows. Selenium could manage redirects, but required extra work to preserve session state. Cypress allowed us to run tests inside a real browser session with state continuity, making these flows easier to test end to end.
We support multiple payment service providers (PSPs), each with different APIs and authentication mechanisms. This resulted in duplicated test flows, inconsistent coverage, and slower regression cycles. We needed a single framework flexible enough to support these variations without bloating the test suite.
Transactions happen on desktop, mobile web, and within in-app browsers. Ensuring consistency across Chrome and Firefox was critical. Postman offered no support here, and Selenium's browser automation came with setup overhead. Cypress made this simpler with more predictable outcomes.
As test coverage expanded, managing sensitive credentials, sessions, and setup steps became a challenge. Postman's environment scripting was difficult to scale, especially across teams.
Postman helped us validate backend functionality in the early stages. But its limitations became apparent as our product matured.
Postman couldn't replicate actual user interactions or test transitions between pages. It could confirm an API returned a success response, but not whether the UI reflected that state.
Each request in Postman is isolated. Managing workflows like login followed by payment and authentication was complex and fragile.
Postman could not check what the user sees. We had no way to confirm whether the UI showed a success message or if redirection occurred as expected.
As our tests grew, Postman collections became harder to maintain. Credentials, test data, and setup logic had to be managed manually.
Selenium is a robust automation tool, but it didn’t align with our priorities.
Selenium tests are typically written in Java or Python. Our front-end team uses JavaScript and TypeScript, so using Selenium would introduce unnecessary complexity.
Selenium runs tests using WebDriver, which increases latency. Debugging test failures often involved reading logs instead of inspecting steps visually. Cypress made this faster with its built-in UI.
Selenium required managing drivers and integrating with CI manually. We were looking for a more developer-friendly approach with minimal configuration.
Cypress gave us a practical and scalable solution.
Cypress fits into our existing stack, and our developers were productive from day one. Its syntax is intuitive and readable.
We could simulate user actions, intercept API calls, and validate UI updates within the same test. This gave us better coverage and faster feedback.
Cypress provides snapshots of each test step, making it easier to pinpoint issues without reading logs.
Cypress integrates smoothly with GitHub Actions. Every pull request now runs tests automatically, helping us catch regressions before they reach production.
Testing payment systems is uniquely complex. Authentication, third-party redirects, and dynamic UI flows are hard to capture with traditional tools. Postman was helpful early on but didn’t scale. Selenium was powerful but required too much setup and didn't fit our workflow.Cypress helped us bring API and UI testing together. It improved reliability, simplified debugging, and enabled developers to take ownership of testing. For any team building interactive, stateful applications—especially in payments—Cypress is a strong choice.