Software Engineer Internship

About the Role

Cairnloop Technologies is seeking passionate and technically strong interns for a Backend / Fintech Software Engineering Internship. This on-site, 3-month internship in Gwalior, Madhya Pradesh, offers hands-on experience in building real-world backend systems and payment workflows.

What You'll Work On

• REST API development and integration
• Payment Collection / Pay-In APIs
• Bulk Payout / Disbursement APIs
• UPI Collect and payment workflows
• IMPS / NEFT / RTGS payment integrations
• Virtual Account systems
• Webhook processing
• Transaction status tracking
• Merchant onboarding workflows
• Bank and payment gateway integrations
• Payment reconciliation systems
• Settlement tracking
• Transaction ledgers
• API authentication and authorization
• Secure backend architecture
• Admin and merchant dashboard backend services
• Production deployment, monitoring and debugging

Requirements & Tech Stack

Backend Development

• Languages: Python / Node.js / Java
• Frameworks: FastAPI / Django / Flask / Express.js / NestJS / Spring Boot
• Concepts: RESTful API design, JSON and HTTP concepts, API versioning and documentation, Swagger / OpenAPI

Database

• Systems: PostgreSQL / MySQL
• Languages: SQL
• Concepts: Database schema design, Transactions and ACID concepts, Indexing and query optimization
• Caching: Redis / caching concepts

Payment & Fintech Concepts

• Protocols: UPI, IMPS, NEFT, RTGS
• Systems: Payment gateways, Pay-In / Collection APIs, Payout APIs, Virtual Accounts, Webhooks / callbacks, Settlement and reconciliation, Transaction lifecycle, Idempotency, Double-payment prevention, Ledger systems

Security

• Protocols: OAuth 2.0, JWT, API Keys, HMAC signatures, Request signing, HTTPS / TLS
• Concepts: Encryption basics, Role-Based Access Control (RBAC), Secure credential and secret management, OWASP API Security basics

Development Tools

• Version Control: Git & GitHub
• Testing & Debugging: Postman, Logging and debugging, Unit and integration testing
• Infrastructure: Linux basics, Docker
• Processes: CI/CD basics

Cloud & Deployment (Good to Have)

• Platforms: AWS
• Services: EC2 / Lightsail, S3, RDS
• Server Management: Nginx, Domain and SSL configuration, Basic server administration
• Deployment: Docker-based deployment

Strong Preference For Candidates Who Understand

• Asynchronous programming
• Message queues
• Background jobs
• Redis queues / RabbitMQ / Kafka concepts
• High-concurrency API systems
• Rate limiting
• API retries and timeout handling
• Idempotency keys
• Audit logs
• Transaction locking
• Database consistency
• Microservices concepts
• WebSocket / real-time systems

What We Value

Candidates who can:

• Understand a problem deeply
• Write clean and maintainable code
• Learn APIs quickly
• Read technical documentation
• Debug real production issues
• Think about security and reliability
• Take ownership of their work
• Build systems instead of only copying tutorials

Bonus Skills

Knowledge of:

• Banking APIs
• Payment gateway APIs
• NPCI payment ecosystem
• PCI-DSS concepts
• Fintech compliance
• API security
• Reconciliation systems
• Accounting / ledger architecture
• React / Next.js for basic frontend integration

Who Should Apply?

Students and recent graduates interested in Backend Engineering, Fintech, Payments, APIs, Banking Technology, Cloud Infrastructure, or Distributed Systems.