Xinqian Liu

As a Full Stack Developer, I was fully responsible for a backend service that including development, building, and deployment. The technologies I used included React, Next.js, Node.js, NestJs, Postgres, Prisma, Subgraph, etc.

In this role, I faced the challenge of being the sole backend developer on the project. When I joined the company, there was no handover from any previous developer, so I had to independently read and analyze the existing codebase to understand the business logic. For new requirements, I needed to thoroughly analyze and interpret them to make the right technical decisions and prioritize tasks effectively.

Key achievements and problem-solving highlights:

1. Twitter API Integration: I was responsible for integrating the Twitter API into the project. This involved studying the official Twitter documentation, understanding the OAuth authorization flow, and evaluating different access levels. I also reviewed technical requirements to help the team decide on purchasing the appropriate Twitter Developer account plan.

2. Production Performance Issue: After deployment, we encountered severe performance issues due to slow SQL queries. Under a sudden surge in user traffic, the database CPU usage reached 100%, causing service outages. Given the urgency of the production issue, I quickly analyzed the slow queries, identified performance bottlenecks in the SQL, and performed data migration to optimize the system, ultimately resolving the problem.

3. CI/CD Pipeline Improvements: I initiated the implementation of automated test checks in our CI/CD pipeline to ensure that code modifications would not break existing functionality. This significantly improved code stability and reduced the bug rate

As one of only two developers in a startup, I was fully responsible for the front-end projects and a backend blockchain data-fetching service that including development, building, and deployment. The technologies I used included React, Next.js, Node.js, Vercel, Elasticsearch, Solana Blockchain API, Sentry, Doris, MySQL, and others.

During this journey, the main challenge I faced was my lack of prior experience with the Solana blockchain. I had to learn the foundational concepts of Solana blockchain from scratch and successfully delivered features like wallet integration, transaction handling, and transaction data storage within the expected timeline.

While fetching data from the Solana blockchain, I encountered the issue of the data retrieval speed lagging behind Solana's block production rate. By step-by-step testing of RPC response times, server bandwidth, and optimizing the parallel data processing in the code, I was able to identify the bottleneck and optimize the performance.

Additionally, I advocated for and implemented Sentry for service monitoring and alerting, ensuring service stability and enabling timely issue resolution.

Work with Parallel Finance at its beginning, I participated in the whole Parallel product building. Led the frontend development, actively engaging in requirement management, and critically reviewed designs, emphasizing the concept of maximum component reuse to optimize efficiency and minimize redundant efforts; Design and develop multiple off-chain NodeJS service that provide the data for frontend, include Nest.js, Graphql and Postgres, etc; Established a robust CI/CD pipeline for continuous deployment utilizing GitHub actions. Implemented a comprehensive monitoring and alert ecosystem with AWS CloudWatch, PagerDuty, and Slack, ensuring swift responses to incidents within the team;

During my tenure, I proactively expanded my skill set by diving into Substrate, Solidity, Rust, ethers.js, and web3-react, mastering the integration of wallet applications such as RainbowKit and Dynamic. This enabled me to build a cutting-edge Web3 DApp Application, showcasing my adaptability and commitment to staying at the forefront of emerging technologies in the blockchain space.

Beyond coding, I contributed significantly to business analysis by meticulously reviewing designs and requirements, breaking them down into actionable stories and tasks, providing clear guidance for the team's next steps. Effectively managed project deliveries, skillfully adjusting priorities and estimating product requirements to ensure timely and successful outcomes.

Focused on enhancing the team's capabilities for Test-Driven Development (TDD) and skill alignment, including writing comprehensive unit tests and end-to-end tests to reduce the occurrence of bugs. Additionally, provided guidance on incident handling and emphasized the importance of creating useful documentation such as repository Readme and troubleshooting documents.

As a Full Stack Developer, I have contributed over three years of dedicated service to REA Group, a prominent global online real estate advertising platform. Throughout this tenure, I collaborated closely with a dynamic, cross-functional team, including Project Managers, Business Analysts, Delivery Managers, and fellow Developers, to successfully deliver a range of impactful products. Notable projects include Audience Maximiser, Listing and Agent Analysis platforms, each designed to deliver substantial value to our customers. Additionally, I actively participated in various innovative HackDay projects, aimed at re-imagining business models and enhancing our daily workflows.

My responsibilities encompassed the end-to-end development of major features, involving both frontend and backend components. I played a pivotal role in technical decision-making and conducted thorough investigations to ensure optimal solutions. technologies such as React, Vue, d3, and styled-components, I crafted visually engaging and user-friendly web applications. On the backend, I employed Scala, NodeJS, Postgres, and elasticSearch to ensure robust and scalable functionality. The deployment process was streamlined through CI/CD using Docker and Buildkite.

My familiarity extends to widely used infrastructure tools, including AWS, Airflow, NewRelic, PagerDuty, JIRA, and Git. Actively involved in knowledge-sharing initiatives, I contributed insights to both the community and our internal team.