From Software Engineer to CTO: What Actually Changes
Subhadeep Datta on going from software engineer to tech lead to co-founder and CTO: the skills that stop mattering, the ones that start, and advice.
Open to advisory, fractional CTO & architecture work
Subhadeep Dattabuilds systems that scale.
I'm a Full Stack Engineer and CTO based in New Delhi, India. Co-Founder & CTO at Hirerkey, Consulting CTO at Noisiv Consulting, and former Technology Lead at Qid. I design backends that handle millions of requests a day, and I write about how to build them.
HirerkeyAI-native HCM platform
6+
Years building production systems
75K
Messages / second through Kafka & Redis
99.9%
Uptime on systems I've architected
20+
Client teams advised across countries
Writing
All 19 articles Field notes from production
Deep dives on system design, performance and AI engineering, written from systems I've actually built and debugged.
How to Approach a System Design Interview: A CTO's Framework
A step-by-step system design interview framework from a CTO who runs them: requirements, estimation, API and data design, deep dives and trade-offs.
Kafka vs RabbitMQ vs Redis Streams: Choosing a Message Queue
Kafka vs RabbitMQ vs Redis Streams compared: ordering, delivery guarantees, replay, throughput and operations, plus a decision guide from production.
Model Context Protocol (MCP) Explained: Build Your First MCP Server
What the Model Context Protocol is, how hosts, clients and servers fit together, and how to build a TypeScript MCP server with tools and resources.
Redis Caching Strategies That Survive Production
Cache-aside, write-through and write-behind in Node.js, plus what tutorials skip: invalidation, TTL jitter, cache stampedes, hot keys and eviction.
Idempotency Keys: How to Make API Retries Safe
How idempotency keys stop double charges when clients retry: the design, a PostgreSQL and Node.js implementation, edge cases and idempotent consumers.
Experience
Case studies Where I've built
- January 2025 - Present
Co-Founder & CTO · Hirerkey
Leading technical strategy and product engineering. Architected the main platform with Java, Node.js, MongoDB, and Kafka. Integrated LLMs and RAG models to automate HR processes, directly contributing to our $2.5M valuation.
- June 2023 - Present
Consulting CTO · Noisiv Consulting
Designing systems that handle millions of daily API requests. Reduced database response times by 60% through schema optimization and implemented Kafka/Redis queues processing 75,000+ messages per second.
- September 2021 - November 2024
Technology Lead · Qid
Managed a team of 5 engineers to build a digital check-in platform. Integrated with India Stack APIs for identity verification and set up Redis caching layers that reduced our database load by 40%.
- September 2021 - June 2023
Partner Technology Manager · Noisiv Consulting
Managed the technology lifecycle for 20+ clients across multiple countries. Implemented MongoDB and Kafka solutions that boosted performance by 35%, and deployed microservices that cut downtime by 60%.
- 2020 - 2021
Software Engineer · Videtorrium
Built core product features using React and Node.js. Mentored junior developers and helped establish our early engineering practices.
Toolbox
What I work with
01Backend & APIs
- Java
- Python
- Node.js
- Golang
- Express.js
- Spring Boot
- NestJS
02Data & Messaging
- MongoDB
- Redis
- Kafka
- MySQL
- PostgreSQL
03Cloud & DevOps
- AWS
- Docker
- Kubernetes
- CI/CD
- Microservices
- Terraform
- Jenkins
04AI & LLMs
- Custom Models
- RAG Models
- Fine-tuning
- LLMs
- Vector Databases
05Frontend & Mobile
- JavaScript/TypeScript
- React.js
- Angular.js
- Next.js
- Flutter
- Android
- iOS
06Leadership
- System Design
- Distributed Systems
- Enterprise Architecture
- CTO Leadership
- Team Management
- Agile/Scrum
- Technical Roadmapping
Let's talk
Scaling something hard? I'd love to hear about it.
Architecture reviews, fractional CTO engagements, performance firefighting, or AI/RAG systems that need to work in production.