Software Engineer Internship

Cairnloop Technologies – Backend / Fintech Software Engineering Intern

Cairnloop Technologies is building technology solutions around digital payments, API integrations, collections, payouts, virtual accounts, reconciliation, and fintech infrastructure.

We are looking for passionate and technically strong interns who want hands-on experience building real-world backend systems and payment workflows.

Role: Backend / Fintech Software Engineering Intern

Location: Gwalior, Madhya Pradesh

Work Mode: On-site

Internship Duration: 3 Months

Students and recent graduates may apply.

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

Technical Skills We're Looking For

Backend Development

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

Database

• PostgreSQL / MySQL
• SQL
• Database schema design
• Transactions and ACID concepts
• Indexing and query optimization
• Redis / caching concepts

Payment & Fintech Concepts

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

Security

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

Development Tools

• Git & GitHub
• Postman
• Linux basics
• Docker
• CI/CD basics
• Logging and debugging
• Unit and integration testing

Cloud & Deployment – Good to Have

• AWS
• EC2 / Lightsail
• S3
• RDS
• Nginx
• Domain and SSL configuration
• Basic server administration
• 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

We are not looking only for certificates.

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?

If you are interested in Backend Engineering, Fintech, Payments, APIs, Banking Technology, Cloud Infrastructure or Distributed Systems, this internship can give you exposure to real-world fintech engineering.