Preethi
Panneerselvam
I architect and operate production backend systems & AWS infrastructure end-to-end — from healthcare-grade compliance platforms to a multi-tenant SaaS I run solo.
Currently architecting a multi-tenant AI-powered SaaS end-to-end as sole engineer— Java 21 / Spring Boot 3, live on Toast POS, Plaid, Stripe & Anthropic Claude. Previously platform engineering at ResMed, owning healthcare-grade audit & authorization systems at production scale.
Twelve years, end‑to‑end ownership.
Lead EngineerFLAGSHIP
DEC 2025 — PRESENTSole engineer architecting and operating a multi-tenant AI-powered restaurant operations SaaS — production system serving 4 paying clients on active Stripe subscriptions.
- Production AWS infra in Terraform — 9 modules / 3 workspaces: ECS Fargate, RDS, SQS with DLQs, API Gateway + Clerk JWT, KMS envelope encryption, SES inbound pipeline.
- End-to-end async invoice OCR pipeline on Anthropic Claude vision — S3 → SQS → PostgreSQL with SHA-256 dedup and exponential-backoff retry.
- Agentic CI/CD with Claude Code — scheduled agent picks Jira tickets and authors changes, every PR gated by ArchUnit tenant-isolation, an LLM eval suite and PII redaction.
Senior Software Engineer
FEB 2022 — SEP 2025Platform engineering on the Connected Health Platform under healthcare-grade reliability and compliance requirements.
- Led a 50M+ record production data migration in the EU environment using versioning and feature flags — zero data loss across distributed consumer services.
- Owned the AuditLog Query Service as a core PaaS capability — 10+ paginated REST APIs with OpenAPI spec and automated contract testing.
- Owned platform authorization end-to-end on AWS Verified Permissions — became division-wide SME and led CloudFormation → Terraform migration.
Microservices Developer
NOV 2020 — FEB 2022- Led AWS modernization for the City of Lethbridge, migrating legacy backends to cloud-native architecture and training the client team.
- Designed and owned the core report engine for Aldo Shoes — Node.js, TypeScript, AWS Lambda, DynamoDB, EventBridge with functional patterns.
Restored an undocumented legacy Pile Modeler no one would take on; raised coverage to 92%, cutting defects 38%.
Built a modular .NET / C# / SQL reporting engine for automated bookkeeping report generation.
Maintained the Charles River Trading System and automated equity-index reporting with SQL and .NET.
Shipped LeaseWave platform modules; owned the Loan Interim Interest module end-to-end with zero production defects.
A production SaaS, run by one engineer.
opspuls.com ↗Multi-tenant AI-powered restaurant operations platform — architected, built, deployed and operated end-to-end. Live integrations with Toast POS, Plaid, Stripe and Anthropic Claude.
Terraform-native AWS
9 modules across global / dev / prod workspaces — ECS Fargate, RDS, SQS + DLQs, API Gateway with Clerk JWT, KMS envelope encryption, SES with DMARC/DKIM/SPF. ~$200/mo all-in.
Async invoice OCR
Claude vision line-item extraction — presigned S3 upload → SQS extraction queue → PostgreSQL with SHA-256 dedup and exponential-backoff retry. Jobs survive ECS task restarts.
Claude Code on rails
A scheduled agent picks Jira tickets and authors changes against custom SKILL.md review skills. Every PR gated by ArchUnit tenant-isolation, an LLM eval suite and a PII-redaction check.
Reconciliation engine
Matches Plaid bank transactions against the invoice ledger via a two-bean orchestrator + executor — external I/O held outside @Transactional to prevent HikariCP pool exhaustion.
Toast POS + Stripe
Per-tenant HMAC webhook secrets and real-time order ingestion (~100 orders/day/location) on one state machine; multi-tenant Stripe billing with PlanFeatureGuard and webhook idempotency.
Distributed by default
ShedLock cross-task scheduling, Resilience4j circuit breakers and per-tenant rate limiters, outbox pattern with SQS drainer. CI via GitHub Actions OIDC, 95% JaCoCo gate.
The toolkit.
Notes from production.
View all →Running a multi-tenant SaaS for $200 a month
How cost-conscious architecture choices keep the entire OpsPuls production footprint — Fargate, RDS, SQS, SES — under $200/month.
Agentic CI/CD: putting Claude Code on rails
A scheduled agent picks Jira tickets and ships PRs — gated by ArchUnit tenant-isolation, an LLM eval suite and a PII-redaction check before automated merge.
Migrating 50M records with zero data loss
Versioning and feature flags made a 50M+ record EU production migration boring — exactly how it should be.
↳ New posts ship as MDX in the repo — commit a file, it goes live.