Optimizing API Performance for a Leading Fintech Platform
Client:
Apex Fintech Solutions
Website:
https://apexfintechsolutions.com/
Industry:
Fintech
Apex Fintech Solutions provides digital clearing and custody services, as well as technology solutions for the wealth management industry. Their clients rely on the Apex API Platform to build real-time, event-driven applications for core financial operations such as account creation, funding, and trading equities. The platform’s performance and scalability are fundamental to delivering
seamless user experiences and maintaining a competitive advantage.
Apex launched a new platform with asynchronous API capabilities to support high-throughput financial operations. However, only ad hoc performance testing had been performed internally.
Given the mission-critical nature of the platform, particularly around order latency and throughput, Apex needed to evaluate its readiness under load, uncover performance bottlenecks, and prepare for scalable growth.
We collaborated with Apex to design and execute a comprehensive performance testing strategy focused on:
• High-volume, business-critical APIs
• End-of-day (EOD) batch operations
• Real-time event message processing
Tool Selection
We recommended OctoPerf, a cloud-based load testing solution, for its ability to:
• Seamlessly import Postman collections to accelerate script development
• Scale from hundreds to millions of virtual users
• Offer flexible licensing options aligned with Apex’sneeds
Scope Definition
Out of 120 active APIs, 12 were selected for testing based on volume, speed requirements, and business criticality.
We also developed 5 utility scripts to automate pre-test setup and post-test validation, improving data accuracy, reducing manual effort and enabling faster iterations.
Custom Event Monitoring
To measure end-to-end latency of transaction-triggered event messages, we created a custom Python-based analysis solution using open-source tools. This allowed real-time visualization of timing deltas and trend analysis on a dedicated dashboard.
End-of-Day Simulation
We designed a robust EOD simulation to test operations like:
• Dividend payments
• Stock splits
• Account statement generation
Simulating high volumes uncovered critical race conditions and queueing issues, which the development team resolved—further hardening the system.
Account Creation API throughput was increased by 7.5 times after uncovering system bottlenecks and resolving throttling points through targeted tuning.
Trading API (Buy/Sell Equities) throughput increased by 99% while maintaining an error-free order fill rate following the identification of key constraints, with enhancements including infrastructure scaling, service optimization, and downstream configuration updates.
System-Wide Insights
• Implemented a monitoring strategy for RPS, response times, and resource utilization
• Uncovered bottlenecks that allowed Apex to identify and implement critical remediations
• Demonstrated benefits of parallel call architecture for reducing latency
Apex gained deep visibility into platform behavior under stress and adopted new tools and best practices for ongoing performance testing. Our collaboration equipped internal engineers with reusable assets and a scalable testing framework for future needs.