Opening the frame

SaravananKalimuthu

Saravanan Kalimuthu

Distributed systems & payments

architecture from discovery to production

Chennai, India9+ years experience

Senior Software Engineer at PayPal

Building reliable payment systems from idea to production.

Senior Software Engineer with 9+ years owning distributed systems across fintech and IoT. At PayPal, led architecture through the full lifecycle — discovery, NFR analysis, phased rollout, and production monitoring — on merchant-facing invoicing and whitelabeling platforms. Known for connecting system-level decisions to measurable outcomes: availability, throughput, fraud reduction, and merchant adoption.

View work Resume Email

99.96%Availability

Service health digests & reliability (from 99.56%)

70%Coverage

Tests with contract tests & mutation testing

<= 2%Spam

Across invoicing APIs (multi-layer detection)

10%Merchants

Webhook delivery feature adoption

Engineering focus

Senior ownership where product, reliability, and delivery meet.

The throughline is pragmatic platform work: reduce uncertainty, shape the system, ship in phases, and leave behind instrumentation that tells the truth.

Architecture

Turn ambiguous product goals into rollout-ready systems.

Discovery, NFR analysis, data modeling, and release plans that make production behavior explicit before implementation.

Data modeling, whitelabeling, webhook delivery, rollout controls

Reliability

Keep services observable, recoverable, and boring at scale.

Health digests, rollback triggers, DLQ alerting, and contract coverage that expose risk while there is still time to act.

Health digests, rollback triggers, DLQ alerting, contract tests

Governance

Balance API growth with fraud controls and platform guardrails.

Progressive access ramps, fraud signals, deduplication, and measurable quality gates across merchant-facing workflows.

Fraud signals, access ramping, deduped delivery, quality gates

Delivery

Lead cross-functional execution from design review to GA.

Clear trade-offs, phased launches, and team rituals that keep technical direction tied to business outcomes.

Phased launches, stakeholder reviews, scrum rhythm, release gates

Core stack

React 19PythonFastAPIElectronPyTorchCLIPSQLiteJavaSpring BootKafkaRedisDatadogBigQuerySpringWebSocketRFID

Selected work

Evidence of systems thinking.

Shipped platforms, open-source tools, and architecture work with outcomes that can be measured instead of merely described.

active

opensource / 2024

Ideal Goggles

Privacy-first AI desktop photo manager — all inference runs locally; zero cloud uploads.

Electron → React 19 → FastAPI → CLIP, InsightFace, and Tesseract → SQLite. Natural language search, face recognition, OCR, and duplicate detection across 100,000+ photos with sub-2s search. Cross-platform macOS, Windows, and Linux. 91+ PRs merged; CI/CD via GitHub Actions with Codecov.

100,000+ photos, sub-2s search
Local-only inference
Full CI/CD pipeline

React 19PythonFastAPIElectron

GitHub

shipped

professional / 2021

Invoicing & Communications Platform

Architecture-led work on merchant invoicing — whitelabeling, aggregation, reliability, and API governance.

Email & URL whitelabeling from discovery to production; invoice aggregation with phased rollout and zero P1s; observability and daily health digests; progressive API gating with fraud signals; webhooks with at-least-once delivery; Redis-backed read path improvements and test modernization.

Availability 99.56% → 99.96%
Coverage ~40% → 70%
Webhook feature: ~10% merchant adoption

JavaSpring BootKafkaRedis

shipped

professional / 2020

RFID / IoT Asset Platform

Industrial IoT tracking with Impinj RFID, real-time maps, and extensible hardware plugins.

Hardware adapter architecture (OctaneSDK, Chronicle Queue, Drools), spatial tracking with WebSocket and Konva maps, plugin model for new hardware, and check-in/check-out with OTA updates for edge devices.

33% hardware cost reduction (tech evaluation)
68% test coverage on event paths
Mock-RFID layer for CI

JavaSpringWebSocketRFID

active

opensource / 2021

Port Advancer

Internal developer tool for port-forwarding and reverse proxying on a restricted corporate network.

Node.js CLI used by 60+ engineers for secure port-forward and reverse-proxy workflows behind corporate restrictions.

60+ engineers
Port-forward & reverse proxy

Node.jsCLINetworking

GitHub

Experience

Production ownership across fintech and IoT.

Roles are summarized around scope, technical decisions, and measurable delivery impact.

2021 - Now

PayPal

Sr Software Engineer / Remote

Invoicing & Communications Platform — merchant-facing invoicing, email & URL whitelabeling, aggregation, and platform reliability.

Email & URL whitelabeling: led discovery through production — custom sender domains, DKIM/SPF/DMARC enforcement, bounce visibility; URL whitelabeling with Apple Pay & routing trade-offs
Invoice aggregation: parent-child data model, phased rollout 5%→GA, rollback triggers & DLQ alerting — zero P1 incidents
Observability: automated daily service health digest — availability 99.56% → 99.96% (~20h recovered annually)

2019 - 2021

AssetPulse

Software Engineer / Chennai

RFID/IoT asset tracking (Industry 4.0) — Impinj readers, real-time location, and extensible hardware integrations.

Evaluated BLE vs RFID; led migration — 33% hardware cost reduction
Hardware adapter: Impinj OctaneSDK → Spring Boot via Chronicle Queue → Drools rules engine; runtime-configurable tag logic
Spatial model & real-time location pipeline (WebSocket); Vue.js + Konva floor-plan maps

2018 - 2019

Wellspring Software Labs

Software Engineer / Chennai

Wholesale distribution ERP (20+ modules) — performance and integration architecture.

Diagnosed data-access bottleneck across modules; query batching & connection management — avg API 1200ms → 700ms
Configurable service locator — decoupled routing from module implementations
C4 architecture diagrams — ~25% faster design reviews with stakeholders

2016 - 2017