Platform that turns courses, coaching, content, and communities into recurring revenue by building, launching, and operating subscription apps end-to-end. Building the product and go-to-market with a business partner.
Hi, I’m Harro
Freelance Full‑Stack Engineer for AI and Product
Hard engineering problems, solved end to end.
Hamburg, Germany · Available remotely
HK
About
I ship software end to end: database, API, UI, infrastructure. I have launched 5 mobile apps, including Elevenstoic, which I built as sole developer and which passed $20K MRR. Right now I run OfficeOS, where we build and operate branded subscription apps for creators on revenue share. I am in the Microsoft for Startups program after building CuePath as sole developer, and I founded Builder Circuit, a Hamburg community of 20+ hackathon winners and early founders, and I am a member of AI Beavers, Hamburg’s AI builder community. I work remotely with teams that need someone to take a product from architecture to release.
Services
What I can help with
Remote, embedded with your team, from first scope to production.
Stack
What I build with
Every tool here is running on something I shipped.
ReactFrontend for every web product I build.
The OfficeOS platform, the Builder Circuit site, and this site are React, from component work through deployment.
Next.jsThe framework those apps run on.
OfficeOS, Builder Circuit, and this site are Next.js — App Router, server components, and API routes.
TypeScriptDefault language on the web side.
OfficeOS, Builder Circuit, and this site are TypeScript end to end — app code, API routes, and the types shared between them.
SwiftNative iOS.
ElevenStoic, the iOS app past $20K MRR, is native Swift — onboarding, paywall, and subscription flow. NoaHealth is Swift as well, against a C# backend over GraphQL.
KotlinNative Android.
The Android build of ElevenStoic is native Kotlin, shipped next to the Swift iOS app rather than shared with it.
Tailwind CSSHow the web products are styled.
OfficeOS, Builder Circuit, and this site are styled in Tailwind — the design tokens and every component built on them.
shadcn/uiThe component base underneath.
OfficeOS and this site sit on shadcn/ui — Radix primitives owned in the repo and extended, not pulled in as a dependency and left alone.
React NativeCross-platform mobile apps.
One of the mobile apps I shipped is built in React Native. Five apps in the stores in total, one of them past $20K MRR.
Node.jsRuntime behind the web backends.
The OfficeOS backend and the API routes on this site run on Node.
C# / .NETBackend services and internal systems.
A year at ECE owning CR Portal, an internal change request system used across departments, including a Data Access Service for Azure DevOps and a refactor of the codebase into clean architecture. The ElevenStoic backend also runs on C#.
RustSystems-level components.
The execution harness of Agent Infrastructure, my open-source control plane for repo-aware coding agents, is written in Rust.
PostgreSQLThe database under the products.
OfficeOS runs on Postgres through Supabase — schema design, migrations, and row level security for every branded app we operate.
SupabaseDatabase, auth, and storage.
OfficeOS runs on Supabase — schema, auth, and storage for every branded subscription app we operate.
GraphQLAPI layer between app and backend.
NoaHealth talks to its C# backend over GraphQL — the schema on the server and a generated Swift client on the app side.
JavaWhere I learned to build software.
The language I worked in throughout my computer science degree, from data structures through larger coursework projects.
SAPEnterprise systems.
Worked with SAP during the year at ECE, alongside owning CR Portal and the Azure DevOps Data Access Service.
AzureCloud infrastructure.
Won $25K in Azure credits in Copenhagen and used Azure heavily throughout the Microsoft for Startups program. At ECE I also built a Data Access Service against Azure DevOps.
DockerHow the services get packaged.
The Fuse backend and Agent Infrastructure ship as containers — the images behind the Kubernetes and AWS deployments.
TerraformInfrastructure as code.
The infrastructure behind Agent Infrastructure is defined in Terraform.
GitHub ActionsCI and release automation.
Build and release automation for ElevenStoic runs on GitHub Actions.
VercelWhere the web products get deployed.
OfficeOS, Builder Circuit, and this site are deployed on Vercel, including preview deployments and domain setup.
CloudflareDNS, CDN, and edge.
Cloudflare sits in front of effectively everything I run — DNS and CDN across the products and sites.
ClaudeAgents, RAG, and AI workflows.
Claude Copy, a published Claude Code plugin, and Agent Infrastructure, an open-source control plane for building, running, and deploying repo-aware agents. I also build RAG pipelines and Claude skills and workflows for teams.
MCPHow agents reach real tools.
Agent Infrastructure serves MCP tools to the agents it runs, with scoped credentials per workspace. obsctl exposes an Obsidian vault the same way, so an agent can read and write notes through a real interface instead of the filesystem.
Google ADKAgents on Google’s stack.
An AI travel agent built on Google ADK for the Lufthansa x Google Hackathon 2026, wired to the Lufthansa Open API and HasData Flights for live flight data.
StripePayments and subscriptions.
Subscription billing for OfficeOS, the platform behind the branded apps we build and operate for creators.
RevenueCatIn-app subscriptions.
Subscriptions for ElevenStoic, the iOS app that passed $20K MRR, run through RevenueCat.
PostHogProduct analytics.
Event analytics in OfficeOS, ElevenStoic, and Fuse — the funnel and retention numbers those products are steered by.
WhatsAppWhere the customers already are.
WhatsApp integration in OfficeOS, for reaching the audiences of the creators whose apps we run.
Cal.comScheduling.
The booking page on this site is a Cal.com month view embedded inline, loaded only on /book so no third party sees a visitor before they ask for a call.
HubSpotCRM.
Used HubSpot to run my own client pipeline.
SlackBots and integrations.
Slack apps and bots that put notifications and approvals in the channel a team already works in.
DiscordCommunity bots.
Discord bots for community automation — the same kind of integration work as Slack, for audiences that live on Discord.
MapboxMaps and navigation.
CuePath, the navigation app for disabled users that won the Disability Tech x Microsoft Hackathon, uses Mapbox alongside OpenStreetMap data and Open Trip Planner for routing.
Selected Work
Products I have shipped
Apps in the App Store, platforms in production, and a hackathon win against 100 competitors. Built end-to-end.
Experience
Where I have worked
Microsoft for Startups, a hackathon win in Copenhagen, and a year owning internal systems inside a large company.
FAQ
Before you book a call
The questions that come up in almost every first call.
Contact
Get in Touch
Want to chat? Just shoot me a message on LinkedIn or send me an email and I’ll respond whenever I can.
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