9+ years shipping distributed systems in fintech and IoT. At PayPal, I lead architecture end to end — discovery, NFR analysis, phased rollout, and production monitoring — on merchant-facing invoicing and email/URL whitelabeling. I connect design choices to availability, throughput, fraud reduction, and merchant adoption.
class SeniorSoftwareEngineer {
constructor() {
this.name = "Saravanan Kalimuthu";
this.role = "Senior Software Engineer @ PayPal";
this.location = "🇮🇳 Chennai, India";
this.contact = "sarvaruna@outlook.com";
}
get skills() {
return {
languages: ["Java", "Python", "JavaScript", "TypeScript", "SQL"],
backend: ["Spring Boot", "JAX-RS", "FastAPI", "Kafka", "Drools", "WebSockets"],
frontend: ["React 19", "Vue.js", "TypeScript", "Electron", "Konva"],
data: ["PostgreSQL", "Oracle", "Redis", "SQLite", "BigQuery"],
observability: ["Datadog", "Splunk", "OpenTelemetry", "Micrometer"],
cloud: ["AWS", "GCP", "Docker", "Jenkins", "GitHub Actions"]
};
}
get currentRole() {
return {
company: "PayPal",
position: "Senior Software Engineer",
team: "Invoicing & Communications Platform",
impact: [
"Service availability 99.56% → 99.96% (daily health digest)",
"Invoice aggregation rollout — 0 P1 incidents",
"Webhook delivery — ~10% merchant adoption",
"Spam on invoicing APIs — <2%",
"Invoice read path — p99 ~1.5× faster (Redis + query redesign)",
"Test coverage ~40% → 70% (contracts + mutation testing)",
"Release cadence — 95% on-time; Scrum quarter — 90% Say-Do"
]
};
}
get openSourceActivity() {
return {
created: [
"Ideal Goggles — privacy-first local AI photo search",
"Port-Advancer — port-forward / reverse proxy for restricted networks",
"utils-commons — Java utilities (Apache Commons–style)"
],
contributed: ["vue-embed-gist — Vue OSS component"]
};
}
}
const saravanan = new SeniorSoftwareEngineer();
console.log(saravanan.currentRole.company); // "PayPal"
Java |
Spring |
Python |
FastAPI |
Kafka |
Docker |
Node.js |
Jenkins |
|
GCP |
AWS |
Postgres |
Redis |
Actions |
React |
Vue.js |
TypeScript |
Electron |
PyTorch |
SQLite |
Also: Spring Data JPA, Hibernate, JAX-RS, Maven, Gradle, Drools (KIE), Chronicle Queue, AMQ, REST/OAS, OAuth2/JWT, Oracle, BigQuery, BigTable, Traefik, Artifactory, Datadog, Splunk, OpenTelemetry, Impinj RFID (OctaneSDK), CLIP, InsightFace, Tesseract, DKIM/SPF/DMARC, OWASP, SonarQube, JaCoCo.
|
Electron · React 19 · FastAPI · Python · PyTorch Privacy-first desktop photo manager — inference runs locally. NL search, InsightFace, OCR (Tesseract), duplicate detection over 100k+ photos with sub-2s search. CI/CD on GitHub Actions + Codecov. 
|
Node.js Internal tool for port-forwarding and reverse proxying on restricted corporate networks — used by 60+ engineers.
|
|
Java General-purpose utilities (String, Number, Date, collections, BLOB, Zip) inspired by Apache Commons IO.
|
Vue · OSS contribution Contribution to a Vue component for embedding Gists — 270+ weekly npm downloads. 
|
gantt
title Career timeline (resume v4)
dateFormat YYYY-MM
section Roles
CoreNett Technologies :done, 2016-06, 2017-12
Wellspring Software Labs :done, 2018-02, 2019-09
AssetPulse :done, 2019-10, 2021-05
PayPal (Sr Software Engineer) :active, 2021-05, 2026-12
section Focus
Java & Spring / distributed :done, 2016-06, 2026-12
IoT / RFID / real-time :done, 2019-10, 2021-05
Payments / invoicing / APIs :active, 2021-05, 2026-12
AI / local inference (Ideal Goggles) :active, 2023-01, 2026-12
@@ PayPal — Invoicing & Communications Platform (2021–present) @@
+ Email & URL whitelabeling — discovery → ADR, DKIM/SPF/DMARC, staging plans
+ Invoice aggregation — phased rollout 5%→GA, 0 P1 incidents
+ Availability — 99.56% → 99.96% via automated daily health digest
+ API governance — progressive access ramp + fraud signals; spam <2% on APIs
+ Webhooks — at-least-once, dedup, fan-out; ~10% merchant adoption
+ Performance — N+1 fix + Redis; p99 ~1.5× under peak
+ Quality — contracts + mutation testing; coverage ~40% → 70%
+ Delivery — 95% on-time releases; Scrum quarter 90% Say-Do
@@ AssetPulse — RFID / IoT (2019–2021) @@
+ BLE vs RFID — 33% hardware cost reduction
+ Spring Boot + Chronicle Queue + Drools rule engine; Vue + Konva floor maps
+ Plugin architecture for hardware; mock RFID layer — 68% coverage on hot paths
@@ Wellspring — ERP (2018–2019) @@
+ API latency — ~1200ms → ~700ms via batching & connections
+ C4 diagrams — ~25% faster design review cycles
@@ CoreNett — CRM (2016–2017) @@
+ Reporting — ~30% faster report generation (pagination)| Degree | Institution | Period | Notes |
|---|---|---|---|
| MCA | University of Madras | 2016–2019 | CGPA 6.48 — thesis: cloud secure storage, double-key encryption |
| BCA | Gurunanak College | 2011–2014 | CGPA 6.24 — internal exam web app; National Honor Society |
 Collaboration Interesting projects |
 Open source Contributing |
 Discussions Tech & ideas |
 Mentorship Knowledge sharing |
📞 +91 979-087-0737 · 📧 sarvaruna@outlook.com
Focus areas: system design · NFR analysis · distributed systems · event-driven & plugin architectures · phased rollout · payments & platform reliability
If you find my work useful:
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"First, solve the problem. Then, write the code." — John Johnson
"Code is like humor. When you have to explain it, it's bad." — Cory House
Thanks for visiting.
Github Gists, inspired by Blair Vanderhoof's gist-embed.