Hi, my name is
Sivabalan Balasubramanian
I build systems that scale under pressure.
Senior Backend Engineer with 11+ years designing async platforms, rule engines, and high-throughput APIs across FinTech and Banking. Currently exploring AI and LLM-powered tools — from on-device privacy gates to intelligent developer workflows.
Featured
Recent Work & Writing
case studyPersonal Project
Building a Local PII Privacy Gate for AI Coding Assistants
How I built a hybrid regex + on-device LLM scanner that blocks prompts containing PII before they reach cloud APIs — zero data leaves the device.
100% PII detection accuracy (25 test cases)50-850ms latency per scan
case studyFinTech
Optimizing a High-Throughput FastAPI Service
How I achieved 50% lower latency and 40% higher throughput on a critical FastAPI service through async pipelines, SQL optimization, and strategic caching.
~50% lower P95 latency~40% higher throughput
articleHow I Built This Portfolio
A technical walkthrough of building sivabuilds.com — the stack decisions, content pipeline, knowledge graph architecture, and the gotchas worth documenting.
nextjsvelitearchitecture
articleRegex vs On-Device LLM for PII Detection: A 25-Case Benchmark
A comprehensive benchmark comparing regex pattern matching against Apple's on-device Foundation Models for PII detection — 52% F1 vs 100% F1, and why binary classification beats extraction.
pythonllmsecurity
experimentactive
GitHub Insights Widget
A Next.js widget that fetches GitHub public data and generates developer insights with a funny summary.
Next.jsTypeScriptGitHub APITailwind CSS
experimentactive
RuleFlow — Dynamic Rule Engine in Node.js
A Drools-style rule engine where business logic runs on editable JSON rules instead of hardcoded conditionals — demonstrated with an airline loyalty program.
Node.jsJavaScriptJSONExpress
Experience
Where I've Worked
Senior Software Engineer
Jul 2024 — PresentACV Auctions
Chennai, IndiaDesigned a modular Rule Engine Platform for credit decisioning, reducing manual review by ~30%. Built a high-throughput FastAPI Performance API with async pipelines achieving ~50% lower latency. Improved observability with structured logging and Datadog APM dashboards.
FastAPIPythonKubernetesPostgreSQLDatadog
Case Study: Rule EngineLead Engineer
Feb 2022 — Jul 2024Lloyds Banking Group
London, UKEngineered low-latency aiohttp async APIs processing millions of regulatory events. Designed Kubernetes workloads with HPA, mTLS, and Spinnaker deployments. Led FaaS pod architecture reducing resource footprint. Reduced pod memory by ~20% through streaming patterns.
aiohttpKubernetesSpinnakerSplunkReact
View projectFull Stack Developer
Sep 2019 — Jan 2022Tiger Analytics
Chennai, IndiaLed end-to-end delivery across backend, frontend, and analytics layers. Built Flask applications with D3.js visualizations for PE firms and BFS/CPG clients. Optimized SQL schemas and ingestion pipelines for high-volume datasets.
FlaskD3.jsReactAngularAzurePower BI
View projectPython Developer
Apr 2018 — Jul 2019KONE
Chennai, IndiaBuilt high-performance Tornado web applications for real-time operational reporting. Improved CI/CD workflows with Jenkins and Docker. Developed Wireshark dissectors in Lua for network protocol analysis.
PythonTornadoDockerJenkinsLua
Python Developer
May 2017 — Dec 2017K7 Computing
Chennai, IndiaBuilt automated scraping pipelines using Requests, BeautifulSoup, and Selenium. Developed ETL workflows and ingestion tools for high-frequency MySQL database updates.
PythonSeleniumBeautifulSoupMySQLETL
Oracle DBA
Jan 2014 — Dec 2015Tata Consultancy Services
Chennai, IndiaPerformed Oracle performance tuning, indexing, and materialized view optimizations. Automated backup and import workflows with Bash scripts across multiple environments.
OracleSQLBashPerformance Tuning
About
A Bit About Me
11+ years across FinTech and Banking — from Oracle DBA to leading async platform architecture at Lloyds Banking Group in London, to designing rule engines and performance APIs at ACV Auctions.
I specialize in the hard parts of backend engineering: systems that process millions of financial events without dropping data, rule engines that make business logic configurable without code deployments, and observability layers that cut debugging time from days to minutes.
MS in Computer Science from California State University, Sacramento. Based in Chennai, working with global teams.
Technologies I work with:
▸Python (asyncio, FastAPI)▸Distributed Systems▸Kubernetes / Docker▸PostgreSQL / Oracle▸System Design▸aiohttp / Tornado▸React / TypeScript▸AWS / GCP / Azure▸CI/CD Pipelines▸Datadog / Splunk▸Rule Engines▸ETL Pipelines
Interested in working together?
I'm open to senior backend engineering roles and interesting collaboration opportunities. Let's talk.