Senior FullStack Developer (AI, Product, Node/React)

Epcnetwork

Warszawa

On-site

PLN 180,000 - 280,000

Full time

5 days ago

Be an early applicant

Get more replies from employers

Send a job-specific resume in minutes.

Benefits offered by this job

Bonuses according to policy

Cozy office in Warsaw

Snacks & beverages

Job summary

EPC Network is seeking a Senior FullStack Developer to own AI-powered internal products and automation platforms from UI to backend, including LLM integrations and production reliability. Work closely with AI, product, and marketing teams, reporting to the Lead of AI.

You will design and implement scalable front-end and back-end solutions, build integrations with external APIs, and configure n8n workflows for social media publishing.

Qualifications

4+ years of commercial software development experience, primarily in full-stack or backend-heavy roles.
1+ year hands-on experience building AI/LLM-powered applications or features.
Strong practical experience with REST APIs, webhooks, and third-party integrations.

Responsibilities

Design, develop, and maintain scalable front-end and back-end solutions for internal platforms, automation workflows, and third-party integrations.
Build and maintain reliable integrations with external APIs and services, including authentication, webhooks, retries, rate limits, and error handling.
Design and configure n8n workflows for automated social media publishing across LinkedIn, X, Threads, and Instagram, including UTM tracking and related automation.
Build and maintain asynchronous processing using BullMQ — queues, workers, schedulers, retries, and failure handling.
Ensure production reliability through structured logging, monitoring, metrics, alerting, and effective troubleshooting.
Write and maintain unit, integration, and end-to-end tests to ensure code quality and system stability.
Participate in code reviews, contribute to architectural decisions, and continuously improve engineering practices.
Take ownership of features end-to-end — from technical design and implementation to deployment, monitoring, and production support.

Skills

Full-Stack Development

AI/LLM Experience

REST APIs

Asynchronous Workflows

PostgreSQL

Redis

Docker

CI/CD

Security & Auth

Code Reviews/Architecture

English Communication

Tools

BullMQ

n8n

LLM APIs

React/Frontend

FastAPI/Node.js

Job description

Location: Warsaw, Poland
Format: On-site
Seniority level: Senior

At EPC Network, we're not just a digital marketing company, we're a platform for career transformation and personal growth. Our people-first approach shapes our corporate culture, fostering a team of passionate, smart, and energetic individuals who strive to grow professionally in an international, fast-paced environment.

As a Senior FullStack Developer, you'll build and own AI-powered internal products and automation platforms end-to-end — from UI to backend services, LLM integrations, and production reliability. You will work closely with the AI team, product stakeholders, and marketing teams, and report to the Lead of AI.

Key Responsibilities:

Design, develop, and maintain scalable front-end and back-end solutions for internal platforms, automation workflows, and third-party integrations
Build and maintain reliable integrations with external APIs and services, including authentication, webhooks, retries, rate limits, and error handling
Design and configure n8n workflows for automated social media publishing across LinkedIn, X, Threads, and Instagram, including UTM tracking and related automation
Build and maintain asynchronous processing using BullMQ — queues, workers, schedulers, retries, and failure handling
Ensure production reliability through structured logging, monitoring, metrics, alerting, and effective troubleshooting
Write and maintain unit, integration, and end-to‑end tests to ensure code quality and system stability
Participate in code reviews, contribute to architectural decisions, and continuously improve engineering practices
Take ownership of features end-to‑end — from technical design and implementation to deployment, monitoring, and production support

Requirements:

4+ years of commercial software development experience, primarily in full-stack or backend-heavy roles
1+ year of hands‑on experience building AI/LLM-powered applications or features
Strong practical experience with REST APIs, webhooks, and third‑party integrations
Experience designing and maintaining asynchronous/background workflows: queues, workers, retries, idempotency, rate limiting, failure handling
Solid knowledge of PostgreSQL and Redis — data modeling, indexing, transactions, caching, performance
Ability to design backend services and make architectural decisions independently
Experience with unit/integration testing, debugging, and maintaining production systems
Practical knowledge of Docker, CI/CD, configuration and secrets management
Understanding of web application security, authentication, and authorization
Hands‑on experience with LLM APIs, structured outputs/tool calling, and production AI integrations; understanding of RAG, embeddings/vector databases, and LLM evaluation is a plus
Experience with n8n or similar automation tools is a plus
Ability to work independently, investigate ambiguous technical problems, and own features from design to production

What it means to be part of our Team:

Multinational and intercultural experience
Growth opportunities, сutting‑edge frameworks and technologies
Plenty of engaging team‑building and social events
Bonuses according to the policy
Cozy office in Warsaw, Kyiv available for you whenever you need it
Coffee, tea, Red Bull, sweets, fruits, and more snacks

Location: Warsaw, Poland
Format: On‑site
Seniority level: Senior

At EPC Network, we're not just a digital marketing company, we're a platform for career transformation and personal growth. Our people‑first approach shapes our corporate culture, fostering a team of passionate, smart, and energetic individuals who strive to grow professionally in an international, fast‑paced environment.

As a Senior FullStack Developer, you'll build and own AI‑powered internal products and automation platforms end-to‑end — from UI to backend services, LLM integrations, and production reliability. You will work closely with the AI team, product stakeholders, and marketing teams, and report to the Lead of AI.

Key Responsibilities:

Design, develop, and maintain scalable front‑end and back‑end solutions for internal platforms, automation workflows, and third‑party integrations
Build and maintain reliable integrations with external APIs and services, including authentication, webhooks, retries, rate limits, and error handling
Design and configure n8n workflows for automated social media publishing across LinkedIn, X, Threads, and Instagram, including UTM tracking and related automation
Build and maintain asynchronous processing using BullMQ — queues, workers, schedulers, retries, and failure handling
Ensure production reliability through structured logging, monitoring, metrics, alerting, and effective troubleshooting
Write and maintain unit, integration, and end‑to‑end tests to ensure code quality and system stability
Participate in code reviews, contribute to architectural decisions, and continuously improve engineering practices
Take ownership of features end‑to‑end — from technical design and implementation to deployment, monitoring, and production support

Requirements:

4+ years of commercial software development experience, primarily in full‑stack or backend‑heavy roles
1+ year of hands‑on experience building AI/LLM‑powered applications or features
Strong proficiency in JavaScript/TypeScript (Node.js) or Python (FastAPI), plus solid production experience with React
Strong practical experience with REST APIs, webhooks, and third‑party integrations
Experience designing and maintaining asynchronous/background workflows: queues, workers, retries, idempotency, rate limiting, failure handling
Solid knowledge of PostgreSQL and Redis — data modeling, indexing, transactions, caching, performance
Ability to design backend services and make architectural decisions independently
Experience with unit/integration testing, debugging, and maintaining production systems
Practical knowledge of Docker, CI/CD, configuration and secrets management
Understanding of web application security, authentication, and authorization
Hands‑on experience with LLM APIs, structured outputs/tool calling, and production AI integrations; understanding of RAG, embeddings/vector databases, and LLM evaluation is a plus
Experience with n8n or similar automation tools is a plus
Ability to work independently, investigate ambiguous technical problems, and own features from design to production
English — Intermediate+ (B1/B2+)