- Developed stable backends for the company internal CMS and CRM system, powered by NodeJS, MongoDB, GraphQL, AWS.- Integrated various cloud services such as Twilio, SendGrid, Stripe, to quickly adapt to business requirements.- Optimized various API end points and solve n + 1 query issue- Developed a type-safe form system to handle various complex forms.- Developed a Maths parser to transform human-readable Maths notation into Abstract Syntax Tree.- Optimized CI/CD process, greatly reduce pipeline time and allow faster deployment time.- Writing robust automatic tests at various level (unit test, API test) to ensure product quality.