Steven Obst

Full-Stack Engineer · AI Systems & Integration · API & Workflow Automation

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About

Most technical problems aren't purely technical, and most business problems aren't purely business. I work in the overlap.


I started in ecommerce and FinTech, coordinating developers and turning stakeholder requirements into something a delivery team could actually ship.
Over time I stopped coordinating the systems and started building them myself.

Now I design and ship production systems solo. I own the architecture, drive the AI agents that write a lot of the code, and check their output hard, because that is usually where it breaks.

What I care about is software that survives a regulated, real-world environment instead of falling over the first time someone uses it for real.

I know how software gets scoped, delivered, and kept alive inside a team. I also know how it works down at the code and system level.

I'm at my best where systems have to talk to each other cleanly, and where a brittle manual process needs to become automation you can trust.


Based in Berlin, working in German and English. Security-aware, and comfortable on both sides of the business and technical line.

Full-Stack Engineer AI Systems System & API Integration n8n / Workflow Automation Next.js Python / FastAPI PostgreSQL LLM Orchestration BRAO / GDPR Berlin German / English

Technical Skills

Integration & Pipelines

n8n Orchestration Self-hosted n8n, bidirectional sync between systems, scheduled and event-driven workflows, REST & Webhooks API integration, OAuth flows, webhook architectures, rate-limited clients, Data Ingestion Multi-source pipelines, deduplication, circuit breakers, normalisation into one schema

AI / LLM Engineering

Multi-Model Orchestration Anthropic, OpenRouter: routing by cost and capability per task, Evaluation Pipelines Multi-tier funnels: SQL filter, overlap scoring, batch LLM scoring, re-ranking, Content Generation Multi-step chains with structured JSON handoff and PII safety, Prompt Engineering, JSON Schema Enforcement, RAG

Core Stack

Python, TypeScript, Rust, Bash

Linux, macOS, Windows, Docker, Git

Frontend

Next.js 15 App Router, server/client components, middleware, SSR, React 19 Hooks, context, custom hooks, optimistic UI, real-time polling, TypeScript Strict typing, shared interfaces, type-safe API layer, Tailwind CSS v4 Utility-first, custom themes, responsive design, dark mode

Backend

Python / FastAPI / Flask App factory, Blueprints, background workers, schedulers, JWT auth, Supabase PostgreSQL RPC functions, Row-Level Security, migrations, real-time subscriptions, REST API Design Auth middleware, validation, structured error handling, versioning, Auth & Security JWT/JWKS verification, OAuth (Google/LinkedIn), PKCE flow, RLS policies

Data & Infrastructure

Data Aggregation 29 source parsers, ATS drains, RSS, scrapers, three-layer deduplication, circuit breakers, Resilience Retry logic, rate limiting, health tracking, graceful degradation

Docker, CRON, GitHub Actions, Stripe billing

Project Highlights

External System case mgmt + accounting n8n Gateway sync + anonymisation EU-only · allowlist Supabase dashboard + AI agent REST RPC BRAO- & GDPR-compliant · one AI gateway for every call

Legal-Tech Production System

A BRAO and GDPR-compliant web app for a German law firm, taken from an inherited MVP to production. (Client work, confidential, so this is the architecture rather than screenshots.)

A self-hosted n8n layer syncs it both ways with the firm's case-management and accounting system over REST and webhooks. Every AI call routes through one EU-only anonymisation gateway with a sub-processor allowlist, so nothing identifiable leaves the approved providers. Plus Gotenberg document generation, a court-deadline state machine, and an in-app case-search agent.

Next.js 15 n8n Supabase Azure OpenAI EU Gotenberg BRAO / GDPR
Career Intelligence SaaS dashboard

Career Intelligence SaaS

A three-repo subscription platform I built solo, end to end: a Flask backend, a bilingual Next.js frontend, and a standalone headless aggregator, each with its own CI/CD.

A five-stage pipeline turns raw listings into scored matches: SQL constraints, skill-overlap, batched LLM scoring across parallel workers, then a re-rank on the top group. Model routing is cost-tiered across Anthropic and OpenRouter, output is JSON-schema enforced, and billing runs on credits with atomic RPC deductions and Stripe webhooks.

Next.js 15 Flask PostgreSQL Supabase Multi-Model AI Stripe
Data aggregation pipeline

Data Aggregation Pipeline

A headless ingestion engine that runs unattended across 29 different sources.

29 parsers across REST APIs, ATS systems, RSS feeds, and scrapers pull tens of thousands of records per run into one store. Three-layer dedup (external ID, strict hash, fuzzy hash) with a batch pre-fetch that collapses 3N lookups to three queries. Per-source circuit breakers auto-reset after 24h, and a new source is one parser file plus a config entry.

Python PostgreSQL BeautifulSoup Docker Resilience Engineering
Multi-tenant field sales PWA

Multi-Tenant Field Sales PWA

A mobile-first B2B tool that replaces Excel for FMCG field reps during retail campaigns.

Row-level security on every table via a SECURITY DEFINER membership function, with organisations auto-provisioned on first login. A campaign, category, and variant hierarchy with template cloning, four quantity modes, and idempotent upserts under a unique constraint. Offline-tolerant and built for reps over fifty: big touch targets, minimal typing per order.

Next.js 15 TypeScript Supabase Tailwind Row-Level Security
Solidity security scanner

Solidity Security Scanner

Static analysis plus an LLM deep-review pass for EVM smart contracts, packaged as a subscription product.

Ten vulnerability classes (reentrancy, access control, integer overflow, unchecked calls, delegatecall, and more) checked by pairing Slither with a Claude review pass. Verified source from eight EVM chains via Etherscan, three scan depths by tier, and a no-exploit-no-report rule against false positives. Backed by 154 tests.

Python FastAPI Slither Anthropic Next.js Stripe

Experience Highlights

2024 to now

Independent Engineering & Production Delivery

I architect and ship production systems solo across FinTech, legal-tech, B2B SaaS, and DeFi tooling.
The workflow is AI-augmented: I own the architecture, let multiple agents generate code, and validate their output closely before it ships.
Paid client work delivered end to end, including a German legal-tech platform and SMB websites.

Oct 2021 to Dec 2024

Technical Project Manager · Better Payment GmbH

The main technical escalation point between onboarding and engineering for a FinTech SaaS platform.
I ran the full delivery cycle: requirements intake, sprint planning, developer coordination, release, and client presentation. I also built a WordPress and Zapier onboarding pipeline that turned client information into structured tickets.

2017 to 2019

IT Specialist · Getränke Stöhr GmbH

Sole IT contact for 50+ staff across office and warehouse operations. I built a WordPress and WooCommerce webshop that handled 100+ orders a month, wired into warehouse delivery.

Systems & Architecture

The patterns and tools I build into production systems

Modular DesignComposable systems with clear boundaries: plug-in sources, swappable AI models, isolated repos sharing one database Pipeline ArchitectureMulti-stage evaluation funnels with progressive filtering and cost-aware model routing REST API DesignFlask/FastAPI with auth middleware, validation, structured error handling Database Schema DesignPostgreSQL with RPC functions, Row-Level Security, migration system Runtime ResilienceCircuit breakers, retry logic, concurrency control, health tracking, graceful degradation n8n Workflow OrchestrationSelf-hosted n8n, bidirectional system sync, credentials, retries, triggers Bidirectional SyncKeeping two systems of record in step over REST and webhooks, with conflict handling API IntegrationREST APIs, OAuth flows, webhooks, rate-limited clients across third-party systems Signal FilteringMulti-layer noise reduction: dedup, hash matching, relevance scoring Multi-Model OrchestrationCost-aware routing across Anthropic and OpenRouter: different models for different tasks AI Evaluation PipelinesParallel batch scoring with progressive filtering, from thousands of candidates to ranked shortlists LLM Content GenerationMulti-step chains: analysis → generation → review, with structured JSON handoff and PII safety Prompt EngineeringFew-shot, Chain-of-Thought, JSON output shaping, injection hardening Anonymisation GatewaysRouting every LLM call through a single PII-stripping, EU-only sub-processor allowlist Next.js / ReactApp Router, server/client components, custom hooks, context, real-time polling TypeScriptStrict types, shared interfaces, type-safe API client layer Tailwind CSSCustom themes, responsive design, dark mode, component-level styling Real-Time UILive status displays, polling, optimistic updates, loading states, error boundaries Progressive Web AppsOffline-tolerant PWAs, mobile-first layouts, large touch targets FastAPI / Flask / PythonApp factory, Blueprints, schedulers, background workers, JWT auth Supabase PostgreSQLRPC functions, RLS policies, JWKS verification, admin vs anon clients Auth & SecurityJWT/JWKS verification, OAuth (Google/LinkedIn), PKCE flow, session refresh Background WorkersScheduled jobs: data fetching, evaluation, sync, daily catch-up Billing SystemsCredit-based billing, atomic RPC deductions, Stripe webhooks, fallback handling Data AggregationMulti-source ETL: APIs, ATS drains, RSS feeds, HTML scrapers, all normalised into one schema DeduplicationMulti-layer: external ID, strict hash, fuzzy hash with description fingerprinting Web ScrapingStructured extraction, rate limiting, scheduled runs, normalisation Data WranglingCSV workflows, Google Sheets automation, regex parsing, signal extraction Docker & CRONContainerized services, scheduled aggregation, health monitoring, keepalive scripts Resilience EngineeringRate limiting, circuit breakers, exponential backoff, health dashboards GitHub WorkflowsMulti-repo management, branch-per-sprint workflow, CI scripts Solo Product DevelopmentRoadmap, sprint planning, iterative delivery, all self-managed across phases Stakeholder TranslationConverting vision to technical scope, feature mediation, cross-department coordination Client OperationsOnboarding flows, CRM systems, support tooling, delivery coordination GDPR / DSGVO ComplianceData export, account deletion, PII stripping, cookie consent, legal pages

Let's build something.

I'm available for freelance projects in system integration, AI/LLM, and full-stack development. Based in Berlin, working remote across the DACH region.

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