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Senior full-stack engineer with 10+ years delivering production SaaS products end to end—from product discovery and responsive UI to backend APIs, data, cloud deployment, observability, and smooth handover. Strong hands-on experience across Next.js, React, TypeScript, Node.js/Express, REST, PostgreSQL, and Stripe Billing, including RBAC, admin workflows, reliable webhooks, subscriptions, and customer self-service. Built AI-powered features using OpenAI and Anthropic APIs with structured outputs, tool calling, retrieval/RAG, prompt versioning, model routing, tenant usage controls, and evaluation/guardrails. Delivered multi-tenant architectures, tenant-aware authorization, async AI jobs, and production-ready observability with CI/CD, Sentry, and OpenTelemetry.…Senior full-stack engineer with 10+ years delivering production SaaS products end to end—from product discovery and responsive UI to backend APIs, data, cloud deployment, observability, and smooth handover. Strong hands-on experience across Next.js, React, TypeScript, Node.js/Express, REST, PostgreSQL, and Stripe Billing, including RBAC, admin workflows, reliable webhooks, subscriptions, and customer self-service. Built AI-powered features using OpenAI and Anthropic APIs with structured outputs, tool calling, retrieval/RAG, prompt versioning, model routing, tenant usage controls, and evaluation/guardrails. Delivered multi-tenant architectures, tenant-aware authorization, async AI jobs, and production-ready observability with CI/CD, Sentry, and OpenTelemetry.

Pawel Hoszowski

Full Stack Developer, AI Engineer, Software Engineer, +3

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Senior full-stack engineer with 10+ years delivering production SaaS products end to end—from product discovery and responsive UI to backend APIs, data, cloud deployment, observability, and smooth handover. Strong hands-on experience across Next.js, React, TypeScript, Node.js/Express, REST, PostgreSQL, and Stripe Billing, including RBAC, admin workflows, reliable webhooks, subscriptions, and customer self-service. Built AI-powered features using OpenAI and Anthropic APIs with structured outputs, tool calling, retrieval/RAG, prompt versioning, model routing, tenant usage controls, and evaluation/guardrails. Delivered multi-tenant architectures, tenant-aware authorization, async AI jobs, and production-ready observability with CI/CD, Sentry, and OpenTelemetry.…Senior full-stack engineer with 10+ years delivering production SaaS products end to end—from product discovery and responsive UI to backend APIs, data, cloud deployment, observability, and smooth handover. Strong hands-on experience across Next.js, React, TypeScript, Node.js/Express, REST, PostgreSQL, and Stripe Billing, including RBAC, admin workflows, reliable webhooks, subscriptions, and customer self-service. Built AI-powered features using OpenAI and Anthropic APIs with structured outputs, tool calling, retrieval/RAG, prompt versioning, model routing, tenant usage controls, and evaluation/guardrails. Delivered multi-tenant architectures, tenant-aware authorization, async AI jobs, and production-ready observability with CI/CD, Sentry, and OpenTelemetry.

Available to hire

Senior full-stack engineer with 10+ years delivering production SaaS products end to end—from product discovery and responsive UI to backend APIs, data, cloud deployment, observability, and smooth handover. Strong hands-on experience across Next.js, React, TypeScript, Node.js/Express, REST, PostgreSQL, and Stripe Billing, including RBAC, admin workflows, reliable webhooks, subscriptions, and customer self-service.

Built AI-powered features using OpenAI and Anthropic APIs with structured outputs, tool calling, retrieval/RAG, prompt versioning, model routing, tenant usage controls, and evaluation/guardrails. Delivered multi-tenant architectures, tenant-aware authorization, async AI jobs, and production-ready observability with CI/CD, Sentry, and OpenTelemetry.

Skills

Experience Level

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Intermediate

Intermediate

Intermediate

Intermediate

Work Experience

Senior Software Engineer at Allegro

August 1, 2023 - Present

Owned delivery of a multi-tenant AI operations product from architecture through production using a Next.js/TypeScript frontend, Node.js services, and PostgreSQL. Built responsive workflows and admin tooling for tenant configuration, usage analytics, user management, and AI review operations. Designed REST APIs and authorization middleware with Express, Prisma, RBAC, and tenant-scoped queries to enforce organization isolation and protect administrative actions. Implemented OpenAI and Anthropic integrations via a provider abstraction supporting structured outputs, prompt versioning, retries, token budgets, model routing, audit traces, and per-tenant usage limits. Delivered asynchronous AI jobs with Redis-based controls, added evaluation and fallback handling, and set up CI/CD, staged releases, Sentry/OpenTelemetry monitoring, runbooks, and handover documentation.

Senior Software Engineer - AI SaaS & Full-Stack Product Delivery at Allegro

August 1, 2023 - Present

Owned delivery of a multi-tenant AI operations product from architecture through production, combining a Next.js/TypeScript frontend, Node.js services, PostgreSQL, and secure cloud deployment. Built responsive workflows and admin tooling for tenant configuration, usage analytics, user management, feature access, and AI review operations. Designed REST APIs and authorization middleware with Express, PostgreSQL, Prisma, RBAC, and tenant-scoped queries to enforce organization isolation. Integrated OpenAI and Anthropic models through a provider abstraction with structured outputs, prompt versioning, retries, token budgets, model routing, audit traces, and per-tenant usage limits. Implemented asynchronous AI jobs, Redis rate controls, evaluation and fallback handling; established CI/CD, staged releases, Sentry/OpenTelemetry monitoring, runbooks, and handover documentation.

Full Stack Developer at EPAM Systems

April 1, 2019 - March 31, 2023

Led implementation of a configurable enterprise SaaS platform using React/Next.js, TypeScript, Node.js/Express, PostgreSQL, and Redis with user, manager, and administrator roles. Created REST endpoints for authentication, business rules, reporting, audit history, and user administration; introduced OpenAPI contracts, validation, centralized errors, and integration tests. Added an AI-assisted workflow using retrieval, tool calling, and structured responses to analyze tenant data and generate recommendations while requiring approval for high-impact actions. Designed tenant-aware data access, entitlements, API quotas, and audit logs; containerized services and automated migrations, GitHub Actions releases, monitoring, and handover.

Software Engineer at Netguru

May 1, 2015 - March 31, 2019

Shipped subscription SaaS MVPs for early-stage clients, translating product concepts into responsive React/TypeScript interfaces, Node.js/Express APIs, and PostgreSQL schemas for production releases. Implemented Stripe Checkout and subscription billing with plan selection, trial and renewal flows, Customer Portal access, invoices, cancellation handling, and entitlement updates. Built reliable Stripe webhook processing using signature verification, persisted event IDs, idempotent handlers, retry-safe state transitions, and reconciliation jobs for missed events. Developed multi-role authentication, password reset, admin dashboards, user management, analytics, tenant configuration, automated deployment, and client handover documentation.