Open to backend & full-stack roles

Backend engineer building the systems fintech runs on.

I'm Sayan. 3+ years shipping Java / Spring Boot backends for enterprise fintech: payment infrastructure, KYC onboarding, authentication and large-scale platform migrations under production load. Based in Kochi, India.

View experience See projects
github · linkedin · email
// 01
3+ yrs
Building enterprise fintech backends in production
// 02
5,000+
Lines of legacy code removed during a live migration
// 03
3.4 → 4.0
Spring Boot major version migrated end-to-end
01 — about

Backend depth, full-stack range.

REF: ABT-01

I specialize in RESTful API design, payment and KYC infrastructure, and authentication and security, with hands-on experience running large backend migrations while the platform is under production load.

Alongside the backend work, I build Angular and React frontends and ship Python / FastAPI services. Most recently I built a real-time AI voice assistant backend using WebSocket audio streaming and MCP-backed chat.

I care about clean layering, predictable APIs and code the next engineer can read without a walkthrough.

Location
Kochi, India
Experience
3+ years · UST
Focus
Java · Spring Boot · APIs
Open to
Germany · UAE · India
02 — experience

Where I've shipped.

Three and a half years at UST, growing from Developer I on an enterprise AI search platform to Developer II owning fintech payment and security backends.

Developer II · Software Engineer

USTFintech client platformFull-time
Current

Own backend services for an enterprise fintech platform spanning investment, wallet and trading workflows. Led the Spring Boot 4 migration, built the Stripe payment and KYC layer, and hardened authentication end-to-end.

3.4 → 4.0Spring Boot migration under production load
5,000+ LOCLegacy code retired during the migration
MFA + JWTOTP auth shipped, token signing upgraded
Key work
  • Migrated a fintech backend from Spring Boot 3.4.3 to 4.0.5 on a layered Controller–Service–Repository architecture, removing 5,000+ lines of legacy code.
  • Designed and built RESTful APIs powering investment, wallet and trading-console workflows.
  • Engineered Stripe payment infrastructure with KYC verification, bank tokenization and automated customer onboarding.
  • Implemented OTP-based multi-factor authentication and upgraded Spring Security and JWT token signing.
  • Rebuilt the client platform frontend on Angular 20 with lazy-loaded, role-based routing.
  • Built a real-time AI voice assistant backend with WebSocket audio streaming and MCP-backed chat.
JavaSpring Boot 4Spring SecurityJWTStripePostgreSQLAngular 20WebSocketMCPDocker

Developer I · Software Engineer

USTEnterprise AI search platformFull-time
AI / Search

Worked across the backend and React frontend of an enterprise generative-AI search product on Azure, focused on making LLM answers traceable back to their source documents.

AzureCognitive Search + Blob Storage integration
CitationsSource links surfaced in every AI answer
LLMSystem prompts tuned for relevance
Key work
  • Enhanced the Azure Cognitive Search integration to return source-document Blob Storage URLs alongside query responses, enabling citation display in the UI.
  • Built React UI components to render citation links and improve transparency in AI-generated responses.
  • Refined LLM system prompts to improve backend response quality and relevance.
Azure Cognitive SearchAzure Blob StorageReactPythonLLM promptingREST
03 — projects

Built on the side.

Independent projects where I explore retrieval, matching and infrastructure ideas end-to-end.

PRJ 01

RAG Copilot

A retrieval-augmented generation backend that answers developer questions on EU visa eligibility, degree recognition and salary benchmarks, grounded in a curated document store.

ChromaDBSQLiteOllamaPython
PRJ 02

Resume-Based Job Matcher

Scrapes and aggregates job listings from multiple sources, then matches roles by skill, location, experience and title, with a dashboard for tracking applications.

FastAPISQLiteReactScraping
See live demo
PRJ 03

Cyber Range Simulation

A cloud-based cyber-training environment with DevOps-driven infrastructure provisioning, VM lifecycle management and centralized log visualization.

AzureAngularFlaskDevOps
04 — stack

Tools of the trade.

Strongest in the JVM backend stack, comfortable across the rest of the delivery path.

Backend

[ 07 ]
JavaSpring BootSpring SecurityRESTful APIsMicroservicesJWT / OAuthMFA / OTP

Languages

[ 05 ]
JavaPythonTypeScriptJavaScriptSQL

Frontend

[ 04 ]
AngularReactRole-based routingLazy loading

Data

[ 04 ]
PostgreSQLSQLiteChromaDBAzure Cognitive Search

Cloud & Infra

[ 05 ]
DockerMicrosoft AzureDocker ComposeLinux (Ubuntu)Self-hosted servers

Tooling & AI

[ 07 ]
FastAPIGitPostmanWebSocketsMCPOllamaRAG

B.Tech, Computer Science & Engineering

Saintgits College of Engineering · Kerala, India

Aug 2018 — Jun 2022CGPA 7.44 / 10
05 — contact

Let's build something reliable together.

I'm open to backend and full-stack roles across Germany, the UAE and India. If you're hiring, or want to talk Spring Boot, payments or platform migrations, my inbox is open.

Email me Connect on LinkedIn
sayanbinujacob@gmail.com linkedin.com/in/sayan-jacob github.com/sayanjacob