Enhanced system stability and fault tolerance and optimized DB performance by designing a robust DB read/write separation.

• Identified data inconsistency scenarios, defined the rules to prevent read-after-write issues, and implemented them in the foundation package.

• Added db sync delay to the datadog dashboard and added an alert for the sync delay.

• Documented and shared the mechanism at the backend committee meeting.

Tuned the performance:

•  Worked with the members to tune the performance of the newly launched API endpoint and reduce the error rate from 0.03% to 0.001% (1000~2000 requests/sec) to meet the SLA. 

  • Analyze the Datadog to identify the bottleneck. 

  • Adjust the k8s scale-up strategy based on the usage of resources, like CPU, memory, number of pods, etc. 

• Coach the junior member on improving the throughput of the voucher generator from 10,000 to 1,000,000 through using the goroutine.

Expanded subscription services in the EU market, increasing overall annual revenue:

• Worked together with the mid-level engineer to develop the new business flow to “record billing addresses when purchasing a subscription” to meet the legal requirements in Turkey.

• Developed the new business flow to “work around the legal issue for refunding in Hungary” and rolled out the subscription service successfully before the deadline.

• Served as the lead engineer in Norway to ensure the successful launch implementation.

Saved the cost for changing plan benefits by leading the development of new features, which can dynamically change plan benefits without affecting existing users.

• Served as a tech lead, working together with frontend and backend engineers on developing the new feature.

Demonstrated leadership by mentoring junior engineers in 

• Documented the code architecture to guide junior engineers on how to implement their new features.

• Shared with the team how to explain MySQL queries to ensure we use the index correctly. 

Served as a member of the backend committee, assisted in hosting the meetings, and served as a technical speaker.

Increased concurrency by 10 times to meet the business’s requirements by leading the team in building a cybersecurity platform: 

• Decouple the logic of executing cybersecurity tools from API business logic.

• Dynamically scale up based on the number of tasks based on Azure’s batch service.

• Standardize the executing command to run Docker containers for security tools, decoupling the usage of security tools from the codebase.

Facilitated seamless communication across 10 web/app products by implementing JWT (OIDC flow) and replacing the outdated SAML flow by leading junior engineers in creating an authentication service handling up to 7,500 logins per hour.

Improved service stability by reducing the number of system crashes to 0 by identifying and addressing online performance issues:

• Figured out the root cause of memory leak by analyzing the JVM heap dump.

• Fix occasional CPU overload issues by profiling the Java application.

• Found out the root cause of the cache missing issues by surveying how the memcache cluster works.

Raised sign-up/sign-in conversion by serving as project lead to collaborate with stakeholders and mentoring junior engineers to refactor the business logic to simplify authentication flow to enhance user experience.

Improved release quality:

• Integrated static analysis (SonarQube) into the CI flow, increasing the test coverage from 5x% to 7x%.

• Implemented API automated testing to the CI/CD.

• Implemented Infrastructure as Code (IaC) to reduce the deployment time from hours to minutes.

Proposed and implemented the CI/CD infrastructure to speed up the deployment from hours to minutes.