Ioannis Stavropoulos

Full-Stack Software Engineer

TypeScript full-stack / SaaS / fintech / payments

Athens, Greece

00 / CONTACT

Emailioannis@stavropoulos.dev
Webstavropoulos.dev
LinkedInlinkedin.com/in/ioannis-stavropoulos-profile

Profile

Full-stack engineer with 5 years across payments and SaaS: card systems and SQL performance at Nexi, multi-tenant SaaS in TypeScript, NestJS, and AWS at Denovo. Comfortable owning features end to end and doing the reliability work (queues, idempotency, migrations) that keeps production quiet.

Work Experience

Denovo

Software Engineer

Jun 2025 - Present

TypeScriptNestJSVuePostgreSQLAWSBullMQStripeMulti-tenant SaaS

Build and maintain a multi-tenant SaaS platform across NestJS, Vue, PostgreSQL, and AWS, owning features end to end from data model to UI.
Reworked notification delivery for a Denovo client with a multi-million-user platform, replacing a fragile single-threaded cron with an outbox-based BullMQ pipeline (retries, lease-based recovery, idempotency) load-tested at ~10k notifications/sec across push, SMS, and email.
Built operational Stripe tooling for charges, refunds, and customer onboarding/offboarding, covering billing flows the product code didn't yet handle.

Nexi

Software Engineer / Application Developer

Mar 2023 - Jun 2025

Oracle SQLPL/SQLCard SystemsSQL TuningRiskShield

Tuned Oracle SQL for card-authorization and transaction-search services, reducing average latency from ~1s to under 200ms and restoring SLA compliance.
Delivered real-time localized cardholder notifications for card actions and transaction events, easing first-line support demand.
Implemented database triggers and queues for secure SMS and PIN-change alerts, maintaining over 99% delivery success.
Built a nightly RiskShield card-activity feed for fraud-detection processing, replacing manual data uploads.
Extended the internal clerk portal (Angular) with new screens and the REST APIs behind them.

Earlier Experience

Blocktech

Front-End Developer

Apr 2021 - Dec 2022

ReactTypeScriptWebSocketsPerformance

Built and optimized a real-time cryptocurrency-exchange trading dashboard using React, TypeScript, WebSocket market data, and virtualized order-book rendering above 50 FPS.

Education

IEK Vergi

IT Applications Technician

2017 - 2019

Vocational training in SQL, algorithms, and web development.

Tech Stack

Backend & APIs

TypeScriptNode.jsNestJSREST APIsPrismaBullMQ

Frontend

ReactVueNext.jsAstroTailwind CSSCypress

Cloud & Infra

AWS LambdaSQSSNSCognitoDynamoDBDocker

Data & SQL

PostgreSQLOracle SQLPL/SQLSQL tuning

Payments & Realtime

StripeWebSocketsSSERedis Pub/Sub