Open to opportunities

Rahul Singh

@grayhat

Senior software engineer specializing in backend systems, cloud services, and security-focused fingerprinting solutions.

India

Message

What I'm looking for

I am looking for backend/cloud roles focused on designing scalable, secure systems, with opportunities to work on high-traffic services, security engineering, and technical ownership.

I am a Senior Software Engineer with more than 3 years of experience designing and building robust backend systems and security-focused device and browser fingerprinting solutions. I have worked on high-traffic, low-latency systems and contributed to scalable microservices and serverless architectures.

My experience spans reverse engineering, securing fingerprinting and security SDKs, and improving performance and cost for cloud-hosted services. I have led client integrations for on-premise SaaS deployments, designed decision-making integration layers for GST products, and redesigned core APIs to accelerate development velocity.

I enjoy hands-on systems work—writing in Golang, Rust, Python and C/C++, building automated data aggregations and developer tooling, and conducting malware research and audits to harden security systems. I seek roles where I can design scalable, secure backend solutions and continue to innovate at the intersection of cloud, security, and performance.

Experience

Work history, roles, and key accomplishments

Current

Senior Software Engineer

Current

Perfios

Oct 2025 - Present (5 months)

Built device and browser fingerprinting and security solutions, designing scalable backend systems that handled up to 150 million requests per client per day with 100ms p95 latency. Led reverse-engineering efforts and redesigned Vault and Core API framework to improve development velocity.

Golang Rust AWS Lambda EC2 ECS Redis RabbitMQ Serverless Microservices

Software Engineer

Bureau ID

Apr 2025 - Oct 2025 (6 months)

Designed systems for compliance products and performed reverse engineering and malware research to secure device and browser fingerprinting systems. Redesigned APIs and vault components to improve development speed and customization.

Flask Golang Reverse Engineering Security API Design ReactJS

Senior Software Engineer

Karza Technologies

Apr 2024 - Mar 2025 (11 months)

Improved PDF generation performance (50% faster, 75% cheaper on Lambda) and led client integrations for on-premise SaaS, managing rate limits, quota controls, and billing. Developed scalable microservices with sub-second latencies for GST-ITR processing to aid credit decisioning.

Python RabbitMQ AWS Lambda Puppeteer Microservices Scalability Integration Performance Optimization

Software Engineer

Karza Technologies

Jul 2022 - Apr 2024 (1 year 9 months)

Built a decision-making integration layer to fetch GST data, reducing integration time from months to days, and developed an in-house PDF parsing solution to cut third-party licensing costs. Created internal developer tooling and a webhook plugin system supporting OAuth and encryption.

Java (Or Unspecified Backend)API Design GST Integrations PDF Parsing Developer Tooling OAuth Encryption Webhooks