About
I'm Thanas, a software engineer based in Athens, always curious about how great software is designed, built, and maintained. Throughout my career, I've worked across frontend, mobile, and backend, which means I still enjoy jumping between the UI, APIs, and the systems that keep everything running behind the scenes.
After spending years writing code across different parts of the stack, I now find myself increasingly drawn to the bigger picture: system design, architecture, and the technical decisions that shape products over time. I enjoy thinking beyond individual features and focusing on how software can stay scalable, maintainable, and enjoyable to build on.
I like understanding how things work, whether that's a new language, an unfamiliar architecture, or a production issue that only shows up at the worst possible moment. Solving complex problems is fun, but building something that's simple, reliable, and enjoyable to use is even better.
That drive to understand systems deeply has translated into real ownership: I've designed the spec and owned the end-to-end implementation of production systems serving millions of active users, from event-driven backend infrastructure to the internal tools that keep teams moving fast.
- 7 years of experience
- Started in September 2019
- 1M+ active users served
- Across the consumer platforms I've built
- 3+ systems owned end to end
- Subscriptions service, campaign builder and internal admin tools at Calm
Experience
08/2026 – Present
Principal Engineer · MyAtlasNow- Authored the technical specification and system architecture for a HIPAA-regulated care platform for people living with cancer, turning the product vision into nine subsystems and a phased delivery plan.
- Designed and built the personalized care path engine in TypeScript and PostgreSQL, combining deterministic clinical rules with a single constrained AI step behind an output check, so that only clinically approved content reaches a member.
- Built a two-layer crisis-language safeguard, pairing a pattern-based risk classifier validated against a corpus of nearly 400 labeled phrases with an LLM second check, and routing flagged answers to a clinical review queue.
- Engineered the two-way SMS pipeline on Twilio for the product’s AI care navigator, with idempotent inbound webhooks, a single guarded outbound send path, and A2P 10DLC carrier registration.
- Secured member data and accounts with row-level security on every table backed by a cross-member access test in CI, hashed session tokens, and personal identifiers kept out of request URLs.
- Built core member-facing PWA flows and internal admin tools with Next.js and React, including sign-in, profile, a resource library, and a versioned content library with a clinical approval workflow.
- Led a small engineering team through delivery, sequencing work by dependency across three repositories, reviewing pull requests, and setting the conventions for CI/CD, database migrations, and staging and production environments.
- TypeScript
- PostgreSQL
- Twilio
- Next.js
- React
03/2024 – Present
Senior Full-Stack Engineer · CalmNow- Designed the technical specification and owned the end-to-end implementation of a self-serve campaign builder platform, removing engineering dependency from campaign setup and reducing campaign launch time to under one hour, enabling faster response to partnership and real-time marketing opportunities.
- Engineered scalable backend services in Go for a new event-driven subscription management platform, addressing long-standing scalability and flexibility limitations and enabling Calm’s transition to a multi-app strategy (bundles, discounts, segmented entitlements).
- Designed and integrated subscription payment flows using Stripe and PayPal, improving checkout reliability and supporting scalable billing operations.
- Integrated Auth0 for authentication and authorization, supporting secure user access and scalable identity management.
- Built and maintained internal admin tools from the ground up, delivering full-stack solutions that improved operational efficiency for high-velocity cross-functional teams.
- Collaborated with senior engineering leadership on backend architecture improvements and cross-team initiatives within a high-traffic production environment.
- Ensured high code quality and system robustness through rigorous unit and integration testing to maintain service stability across distributed systems.
- Go
- Stripe
- PayPal
- Auth0
12/2022 – 02/2024
Android Engineer · Calm- Developed and delivered core Android app features using Kotlin and Jetpack Compose, focusing on creating polished, high-performance interfaces for a massive global user base.
- Optimized application performance and responsiveness by leveraging Android Studio, ensuring a seamless mobile experience across a wide range of devices and network conditions.
- Implemented complex UI interaction patterns that have remained a maintainable standard for the mobile team handling high-engagement user flows.
- Partnered closely with product and design to align implementation details and suggest technical improvements for UI behaviors at scale.
- Kotlin
- Jetpack Compose
- Android Studio
04/2022 – 11/2022
Frontend Engineer · Calm- Successfully migrated mobile app designs from Figma into responsive web interfaces using React, Next.js and Material UI for Calm’s expanding web presence.
- Set up the project foundation by creating the web repository and configuring GitHub Actions for CI/CD to automate high-frequency deployment pipelines.
- Built complex UI components with pixel-perfect accuracy, ensuring a consistent user experience for millions of web visitors.
- Implemented Web Accessibility (A11y) standards, including ARIA roles and keyboard navigation, ensuring the platform is inclusive for all users at scale.
- Maintained a robust testing suite by writing integration tests to verify key component functionality and protect critical user-facing flows from regressions.
- React
- Next.js
- Material UI
- GitHub Actions
- Figma
09/2019 – 03/2022
Full-Stack Engineer · Ovio- Developed and styled interactive UIs using React, Next.js, and Material UI, converting design mockups into functional web applications.
- Integrated GraphQL queries and mutations in collaboration with the backend team to optimize data fetching and frontend interactions.
- Contributed across the full stack, providing technical input on both frontend and backend tasks to deliver end-to-end features.
- Performed automated testing using Jest to validate UI components and ensure stable, bug-free deployments.
- Built features using Firebase Authentication and Firestore, enabling real-time updates and scalable backend functionality.
- React
- Next.js
- Material UI
- GraphQL
- Jest
- Firebase
Skills
- Frontend
React
Next.js
Material UI
HTML
CSS
Figma
- Backend
Node.js
NestJS
Express
GraphQL
Flask
- Android
Jetpack Compose
Android Studio
- Programming Languages
Typescript
Javascript
Go
Python
Kotlin
- Databases
PostgreSQL
Supabase
MySQL
MariaDB
MongoDB
SQLite
- DevOps
Docker
Github Actions
Google Cloud
CircleCI
Vercel
Heroku
- Integrations
Firebase
Stripe
Paypal
Twilio
Auth0
Datadog
Amplitude
- Libraries
TanStack Query
React Hook Form
Axios
Apollo Client
i18next
- AI Tooling
Claude Code
OpenAI Codex
Gemini CLI
Education
National Technical University of Athens
School of Electrical & Computer Engineering
2014 – 2021 · Athens, Greece
2014
Admission to NTUA
Electrical & Computer Engineering
Placed among the top scorers nationwide in Greece's university entrance exams (the Panhellenic exams), earning a place in a five year integrated programme in Electrical & Computer Engineering at one of the country's most competitive schools.
Top percentile nationally · Panhellenic exams
2014 – 2021
Integrated Master's Diploma
Joint BSc + MSc
A five year integrated programme that built both a scientific and a technical foundation, with a lasting interest in software and computer systems. It set the groundwork for working end to end across backend, web, and mobile.
- Computer Science
- Software Engineering
- Systems
2021
Diploma Thesis
Resource Allocation Automation for Large-Scale Cloud Applications
A method for minimizing the cost of running large scale workloads on AWS Spot Instances when compute demand is not known in advance. It pairs optimization algorithms with neural networks that forecast both workload size and spot market prices.
- Cloud Computing
- AWS Spot Instances
- Optimization
- Machine Learning
- Neural Networks
2021
Graduated with Top Honors9.00 / 10
Completed the integrated diploma among the very top of the class.
Contact
Let's build something amazing together. Whether you have a project idea, a job opportunity, or just want to say hi, my inbox is always open. I typically respond within 24 hours.