Open to opportunities

Daniel Nicholae

@danielnicholae

Senior full-stack engineer building FastAPI/Django Python backends with React frontends for enterprise SaaS and fintech.

Romania

Message

What I'm looking for

I’m looking to build reliable, high-performance products end-to-end—FastAPI/Django backends and React frontends—where I can optimize reliability and UX, collaborate cross-functionally, and keep improving engineering standards through mentoring and architecture reviews.

I’m a senior full-stack engineer with 9 years building production Python backends with React frontends for enterprise SaaS, Series A health tech, and global fintech. I focus on FastAPI and Django services, accessible component systems, and SOC 2–aligned audit work.

In my recent role, I designed end-to-end cross-border payout systems, improved onboarding performance by replacing blocking flows with event-driven Kafka pipelines, and scaled Payments-domain APIs to sustained 40k requests/sec. I also optimize user-perceived performance (e.g., Next.js streaming SSR), strengthen reliability (idempotent state machines, outbox pattern, retry/circuit-breaker SDKs), and lead through mentoring, architecture reviews, and shared code standards.

Experience

Work history, roles, and key accomplishments

Current

Senior Full-Stack Developer (Python)

Current

Deel

Dec 2023 - Present (2 years 6 months)

Designed cross-border contractor payout platform end-to-end with FastAPI and a Next.js React frontend, using idempotent state machines and the outbox pattern to ensure reliable multi-currency disbursements. Rebuilt onboarding with an event-driven Kafka pipeline, reducing completion time from 9 minutes to under 2 minutes, and sustained 40k requests/sec on Python payment APIs.

fastAPI Next.js React PostgreSQL Apache Kafka AWS RDS Redis gRPC Event Sourcing

Full-Stack Developer (Python)

MyTomorrows

Sep 2021 - Nov 2023 (2 years 2 months)

Owned a multi-tenant appointment-scheduling platform with a React UI and FastAPI services backed by SQLAlchemy/PostgreSQL, preventing double-booking via row locks and Redis slot reservations. Built 30+ HL7/FHIR system integrations, implemented field-level UI masking and per-tenant AWS KMS envelope encryption, and improved booking Largest Contentful Paint from 1.8s to 320ms.

React fastAPI SQLAlchemy PostgreSQL Redis HL7 FHIR AWS KMS Celery LaunchDarkly

Full-Stack Developer (Python)

Bloomreach

Jul 2019 - Aug 2021 (2 years 1 month)

Built React UI components and shared widgets with matching Flask/Celery endpoints for e-commerce catalog and merchandising. Increased test coverage from 45% to over 85% for recommendation widgets, and fixed a Redis cache-stampede issue that caused intermittent 5xx errors during nightly catalog re-imports.

React Flask Celery Jest React Testing Library Pytest Redis Gitlab CI CI CD

Junior Full-Stack Developer

Three Cubes

Jul 2017 - Jun 2019 (1 year 11 months)

Developed adaptive learning React UI using TanStack Query, improving student assessment completion from 54% to 71%. Implemented Python Flask APIs for personalized learning recommendations and optimized ML model serving latency from 1500ms to 380ms via model quantization and caching strategies.

React Tanstack Query Python Flask PostgreSQL Model Quantization Caching