How to Ensure Stability When Testing Third Party Integrations and APIs

August 20, 2025Robust SoftechApplication Testing
How to Ensure Stability When Testing Third Party Integrations and APIs

Modern applications depend heavily on third-party integrations. From payment gateways and CRM sync to messaging APIs and mapping services, external services are embedded in nearly every web and mobile experience.

But while third-party tools save time and add features, they also introduce risk. If one API fails — your checkout might break, user data might not sync, or messages might not get delivered. That’s why testing these integrations for stability is just as important as testing your own code.

At Robust Softech, we’ve worked with U.S.-based SaaS products, delivery platforms, and healthcare apps to build testing layers around APIs and plugins that are outside of their control — and helped reduce outages caused by changes, timeouts, or unexpected failures.

Why Third Party Testing Can’t Be Ignored

When an API fails, your app often takes the blame.

Some common real-world issues include:

  • Payment not going through even when the card is valid

  • Double charges from webhook misfires

  • User info not syncing to CRM

  • Login via OAuth (Google/Facebook) suddenly failing

  • Map services not rendering due to expired API key

  • Shipping calculators timing out mid-checkout

These aren’t just technical failures — they directly affect revenue, support tickets, and customer trust. Most of these could be prevented with structured integration testing.

What to Test When Using Third Party APIs

You can’t control the external service, but you can test how your app interacts with it under different conditions.

Here are critical areas to test:

API Availability

  • Simulate downtime or throttling

  • Test retry logic

  • Monitor uptime with heartbeat pings

Response Handling

  • Validate correct handling of 200, 400, 401, 403, and 500 errors

  • Check for correct fallbacks if API returns unexpected formats

Rate Limits and Quotas

  • Test app behavior when approaching or exceeding API limits

  • Ensure logs track rejected requests

Webhooks

  • Verify that incoming data is validated, authenticated, and idempotent

  • Simulate missing or delayed webhook events

Authentication and Token Expiry

  • Test what happens when tokens expire

  • Validate auto-refresh logic and proper error messaging

Data Sync and Mapping

  • Confirm fields are mapped correctly between systems (CRM, ERP, etc.)

  • Check for missing fields, format mismatches, or silent failures

Tools and Techniques for API Testing

Here’s how we test APIs at different stages of development:

  • Manual API Testing: Postman, Insomnia
  • Automated Testing: RestAssured, Karate, Cypress (for UI-linked APIs)
  • Contract Testing: Pact (Consumer-Driven Contracts)
  • Mocking APIs: WireMock, Beeceptor
  • Monitoring: Postman Monitors, Pingdom, API Fortress
  • Load Testing: JMeter, k6.io

Plugin and Integration Testing

Some apps integrate with tools like:

  • Stripe / PayPal

  • Twilio / SendGrid

  • Shopify / WooCommerce plugins

  • Google Maps / Directions API

  • Slack / Discord / Zoom APIs

  • Google / Facebook Login

  • Zapier workflows or Make.com automations

For these, we write targeted test cases including:

  • UI validation (does the integration load properly?)

  • Backend error handling (what if payment gateway fails mid-transaction?)

  • Data tracing (does webhook match correct user or event?)

  • Timeout simulation and graceful failure

  • Version change testing after SDK or plugin updates

Plugins often break after auto-updates — so test automation includes version snapshots and dependency lock checks.

Client Experience:

U.S. Marketplace App Fixes API Outage Vulnerabilities

A U.S.-based marketplace platform relied on multiple third-party services: Stripe for payments, Google Maps for delivery routes, and Twilio for SMS alerts.

Users often complained of:

  • Missing delivery ETA updates

  • SMS not being received after order

  • Failed charges due to random API timeouts

When they engaged Robust Softech, their biggest pain point was unreliable integrations they couldn’t fully explain or control.

Our solution:

  • Built an API monitoring system that pinged external services every 5 minutes

  • Set up mock APIs to simulate Stripe and Google Maps failures

  • Automated regression tests with retries and timeouts

  • Added webhook logging and fallback notifications for SMS failures

  • Created a staging sandbox with live tokens and throttled responses for simulation

Results:

  • API-related support tickets dropped by 75%

  • Order completion rate increased by 18%

  • The client’s internal team gained visibility into issues without waiting for user reports

  • System alerts were added to detect and respond to partner service outages in real time

This engagement highlighted that your app is only as stable as the APIs it relies on — and how well you prepare for failure.

Client Success Story

How Robust Softech Helps You Build Integration-Ready Systems

Our QA process includes dedicated testing for:

  • All external APIs used by your app

  • Plugins, SDKs, and custom third-party scripts

  • Authentication logic and token expiry

  • Webhook validation, retries, and fallbacks

  • Regression coverage across updates or API version changes

Whether you’re launching a product or scaling to enterprise clients, we make sure your app survives the unexpected — including the parts you don’t control.

Book a free Consultation Now!

Client Success Story

How Robust Softech Helps You Build with Quality from Day One

We work alongside your developers to:

  • Define test coverage goals
  • Choose the right tools for your stack and team size
  • Automate where it helps, and guide where manual testing adds value
  • Catch issues early, not in production
  • Scale QA as your product scales

Whether it's your first app or your fifth platform launch, we embed testing where it matters — at the start.

Book a free Consultation Now!

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Robust Softech

Author at Robust Softech

Expert in technology and digital transformation