API Testing Services

Verify API responses, load handling, and security using tools like Postman, JMeter, or Swagger.

Overview

APIs are the backbone of modern applications. GullySystem ensures your APIs are fast, secure, and reliable with structured functional, performance, and security testing. We validate endpoints, monitor payload behavior, and simulate real-world traffic to ensure your services never fail under pressure.

Benefits

Functional Accuracy

Ensure each API endpoint responds correctly with valid data, headers, and status codes across expected inputs.

Improved System Stability

Detect broken endpoints, timeout errors, or dependency failures before they disrupt the user experience.

Automated Regression Testing

Automate API tests to validate behavior after code changes, deployments, or third-party service updates.

Performance Under Load

Simulate thousands of concurrent API calls to assess how your backend handles real-time demand and stress.

Early Bug Detection

Catch schema mismatches, missing fields, or incorrect error codes before they reach front-end users.

Security Compliance

Verify authentication, token handling, and access restrictions to protect sensitive APIs from misuse.

Our Testing Approach

Requirement Mapping

Understand business logic and expected API behaviors to create accurate test cases and validation rules.

Functional Testing

Send structured API requests with various payloads to ensure expected response of bodies, headers, and codes.

Schema & Contract Validation

Match API responses to OpenAPI (Swagger) specs, flagging unexpected fields, types, or missing data.

Authentication Testing

Validate token-based auth, session headers, OAuth flows, and user roles for protected API routes.

Load & Stress Testing

Use JMeter or k6 to simulate heavy API usage, measuring response times, error rates, and throughput.

Error & Edge Case Testing

Trigger invalid input, empty fields, rate limits, or expired tokens to test robustness and graceful failure.

Tools & Technologies We Use

Postman

Create collections, assertions, and tests for REST APIs—ideal for dev testing and pre-deployment checks.

Swagger / OpenAPI

Use schema specs for contract testing, response validation, and API documentation synchronisation.

JMeter / k6

Simulate traffic to test performance under load—analysing latency, error rates, and throughput metrics.

REST Assured / Supertest

Automate backend tests in JavaScript or Java to validate complex workflows and chained requests.

Newman CLI

Run Postman collections via CI/CD pipelines to auto-test APIs after each commit or deploy.

Security Testing Tools

Use OWASP ZAP or manual scripts to test for injection, broken auth, and insecure API exposures.

Why Choose GullySystem

Full Lifecycle API Testing

From development to post-release, we ensure every API version stays accurate, responsive, and secure.

Manual + Automation Blend

Combine quick manual tests with scalable automation to balance speed, accuracy, and deep coverage.

Cross-Environment Testing

Validate API behavior in dev, staging, and production—ensuring consistency before going live.

Real-Time Reporting

Receive test logs, dashboards, and trace data to monitor API health over time or spot recurring issues.

Secure Testing Practices

We don’t just validate behavior—we test security vulnerabilities in headers, tokens, and payloads.

Support for Any Tech Stack

REST, GraphQL, JSON-RPC, SOAP—we test APIs built with any language or framework, old or new.

Use Cases

SaaS Product APIs

Validate authentication, billing, usage tracking, and customer endpoints to avoid user-impacting bugs.

Mobile App Backends

Ensure APIs that drive mobile features like sync, chat, or payments work under all network conditions.

Third-Party Integrations

Test CRM, payment, SMS, or shipping APIs for uptime, payload structure, and error handling.

E-commerce Platforms

Validate catalog, cart, checkout, and order APIs across regions, currencies, and device types.

Healthcare & Fintech Apps

Test sensitive data transfer, encryption, and compliance standards for secure and auditable APIs.

Legacy API Replacement

Migrate or rewrite old APIs with confidence by running parity and regression tests on endpoints.

Frequently Asked Questions

Yes. We create reusable scripts and collections that run via CI/CD or manually—great for regression and monitoring.

Yes. We test GraphQL queries, mutations, and schemas with automated tools or Postman GraphQL support.

Absolutely. We provide test logs, pass/fail reports, latency stats, and insights after each testing cycle.

Yes. API testing is independent of UI—we test services even before the frontend is built.

No problem. We can create basic schemas from your API responses or reverse engineering request flows.

Ensure your APIs are fast, secure, and reliable. GullySystem’s API testing services protect your integrations and backend systems from failures.

Start API Testing