Daniil Volobuiev
Verified Expert in Engineering
Python back-end Engineer and Developer
Gothenburg, Sweden
Toptal member since August 5, 2026
Daniil is a Python back-end engineer with 3+ years of experience building production APIs, data pipelines, and AI integrations for clients such as Jellyfish, Actionable, and Atomaze. His primary expertise is in FastAPI, LangChain, and Celery for B2B SaaS products, where Daniil thrives in delivering practical solutions with clean architecture and measurable outcomes. He reduced LLM token consumption by 40% while at Jellyfish.
Portfolio
Experience
- Airtable - 3 years
- PostgreSQL - 3 years
- OpenAI - 3 years
- Kubernetes - 3 years
- Redis - 3 years
- Python - 3 years
- FastAPI - 3 years
- LangChain - 3 years
Preferred Environment
AWS IoT, Docker, Kubernetes, GitHub Actions, Git, Linux, Prometheus, Grafana, RabbitMQ
The most amazing...
...RAG system I've shipped improved response accuracy and conciseness for an AI-powered coaching platform by optimizing prompt design.
Work Experience
Python Back-end Engineer
Vital Voices
- Led secure migration of 100,000+ user records and organizational data between legacy and modernized platform systems with minimal downtime.
- Implemented cross-platform SSO infrastructure across multiple internal services, reducing authentication-related support requests and improving user access experience.
- Introduced automated Playwright end to end and visual regression tests, significantly reducing manual QA effort and preventing UI regressions during frequent production releases.
Python Back-end Engineer
Actionable.co
- Improved dashboard query performance by 60% through PostgreSQL optimization, caching strategies, and asynchronous processing.
- Collaborated across product and front-end teams to deliver 20+ analytics and visualization features used by enterprise customers.
- Designed and integrated REST APIs connecting third-party services, implemented automated testing, and collaborated closely with product, design, and QA teams to deliver reliable production releases.
Python Back-end Engineer
Jellyfish
- Implemented a RAG pipeline using LangChain, Airtable, OpenAI embeddings, and vector-based retrieval to improve response accuracy and conciseness in the coaching assistant chat.
- Reduced LLM token consumption by 40% by improving prompt design, limiting context size, and optimizing response formats.
- Built and delivered 20+ production features across AI, analytics, and SaaS products using Python, FastAPI, React, PostgreSQL, and AWS, taking ownership from design through deployment.
Full-stack Software Engineer
MyStrengthBook
- Improved MongoDB query efficiency and indexing strategy, decreasing heavy aggregation query execution times by 60%.
- Developed and delivered 20+ full-stack features using Python, FastAPI, React, TypeScript, and MongoDB, improving the user experience for a fitness platform serving coaches and athletes.
- Optimized complex MongoDB aggregation pipelines and database queries, reducing API response times by up to 60% for analytics and workout history endpoints.
- Designed and implemented REST APIs, responsive React interfaces, and third-party integrations, collaborating with product and design teams to deliver production-ready features from concept to deployment.
Full-stack Software Engineer
Automaze
- Designed and implemented horizontal scaling for ML workloads with Kubernetes, achieving a 2.3x improvement in response speed while maintaining cost efficiency.
- Integrated a Neo4j database to optimize data storage and access, reducing query times by 2x and significantly improving application performance.
- Implemented graph-driven relationship analysis for influencer discovery, reducing lookup times by 2x and improving recommendation relevance.
Experience
IonKol
http://ionkol.comEducation
Master's Degree in Computer Science
V.N. Karazin Kharkiv National University - Kharkiv, Ukraine
Skills
Libraries/APIs
OpenAI API, Pydantic, SQLAlchemy
Tools
Git, Grafana, RabbitMQ, Celery
Languages
Python
Platforms
Kubernetes, AWS IoT, Docker, Linux
Storage
PostgreSQL, Neo4j, MongoDB, Redis
Other
LangChain, FastAPI, Airtable, OpenAI, Single Sign-on (SSO), GitHub Actions, Prometheus, Anthropic Claude API, Qdrant
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