Version Control & Collaboration: Git, GitHub, GitLab, Bitbucket, JIRA, Redmine, Azure DevOps
Payment Integration: Stripe, PayHere, Payment Gateway APIs, PCI DSS Compliance
API Development: RESTful APIs, JSON, Swagger/OpenAPI, API Design Patterns, Webservices
Development Practices: Agile/Scrum, Test-Driven Development, Code Review, Documentation