Open to new work
HelloSalut
I'm Hermann Kao
Versatile developer, from product to infrastructure
What defines me most is adaptability: I pick up whichever language, framework and layer a product needs. Day to day in TypeScript, on web and mobile, but equally at ease in Java, C#, Rust, Swift or Python depending on the context. I work from the product down to the infrastructure (CI/CD, Kubernetes, cloud, monitoring) and have often been a product's only engineer. Since 2025 I have been wiring AI agents into delivery pipelines, from the ticket to a tested pull request.
Work
My path
A quick overview up top, then role-by-role detail below.
Up to 3 assignments running at the same time.
Application integrator and DevOps engineer
B2B equipment financing company (financial group)
Freelance (umbrella company), Saint-ÉtiennePart of the IT department's integration team, supporting the replacement of an AS400 system with a custom ERP built by an external vendor.
- Run the API manager and the connections to external services.
- Support the AS400 to ERP migration on the integration side.
- Ansible automation across the on-premise estate: Java updates, scheduling (VTOM) and metrics (Telegraf) agent rollout, CVE assessment and remediation.
- Developed scheduling automations with VTOM (Absyss).
- Ran blackbox security audits.
- Deployed Cognos (IBM reporting).
- Deployed Outline on AKS (Azure Kubernetes Service), replacing MediaWiki.
Mobile developer, then fullstack developer, then software architect
The After Cancer, health support app (United States)
Freelance, RemoteHired for the mobile app, I later took over the backend and the infrastructure. I am now the product's only engineer: mobile, backend, back office, landing page, infrastructure and data. The app has grown past 300 daily active users.
- React Native (Expo) app with OneSignal, CometChat, Google Calendar and an integration with Healthie, a health data provider.
- AWS architecture (EC2, IAM, logging) with an API Gateway in front of external providers (CometChat, Stripe, OneSignal, Healthie).
- Notion to GitHub pipeline driven by Claude Code. An agent reads the ticket, asks its questions in Notion and opens a pull request with tests. A human still approves every merge. This setup took a feature from ticket to production in one week.
- Deployment pipeline evolution: Ansible scripts, then Kamal, then GitHub Actions to EC2 instances.
- Ephemeral review environment created on AWS for each pull request, removed after 3 days.
Fullstack developer
Versusmind, IT services company (Nancy)
Freelance, then umbrella company, Remote- Rebuilt an international telecom equipment maker's website, moving from Sitecore to Next.js and Payload CMS.
- Maintenance of a Sitecore XP 10 / SXA platform for a national construction trade federation.
- WordPress and PrestaShop maintenance for a glazing e-retailer, including server administration (Debian, Cloudflare Tunnels, SSH hardening).
- Health-claim transmission interfaces to government services, with standardized flows and compliance constraints.
- Set up automated CI/CD deployment for a Flutter application.
- Internal tooling that generates activity reports and multi-project timesheets from the Azure DevOps APIs.
- Contributed to an internal AI agent orchestration project.
- Built a local WordPress development toolkit (Makefile, MCP skills, agent commands).
Fullstack and DevOps developer
Nobo, home cleaning service (Palladium group)
Work-study, then freelance, Boulogne-BillancourtA three-developer team running a platform at 2.5 M€ in revenue.
- Fully automated production and staging releases: GitOps deployment with Argo CD on GKE, managing Google Cloud and OVH servers.
- Optimized GitLab CI and Docker pipelines across several codebases, with a migration to a monorepo organization.
- Integrated RabbitMQ for asynchronous communication between services.
- Set up production error tracking (Sentry) and GDPR compliance.
- Migrated the test suite from Selenium to Playwright, with Detox for mobile end-to-end tests.
- Built a management back office and a customer acquisition funnel.
- Migrated two React Native apps from an Expo 52 monorepo to two independent Expo 57 apps with a hexagonal architecture.
- React Native mobile apps with geolocation, QR code and NFC tag scanning, and encrypted local storage.
- Offline SQLite outbox so that service validation, which triggers billing, survives poor connectivity.
Freelance developer
Short assignments for studios and startups
Freelance- IPLAYAGAIN: React Native mobile app, integration of third-party monetization SDKs (IronSource, Firebase, Facebook) and iOS App Tracking Transparency compliance.
- Clone (formerly Not So Dark): management back office, real-time messaging and API documentation, in a hexagonal architecture.
- Novéup: robo-assistance web app for elderly people, with real-time video and audio calls (LiveKit).
- SideApps: Flutter application, Firebase and Facebook integration, iOS 14+ ad-tracking compliance.
- KatGames: cross-platform React Native games app, Google OAuth authentication, Docker and GitHub Actions CI/CD.
System administrator
Snowtrust (Limoges)
Freelance- OpenStack infrastructure and a Kubernetes cluster built from scratch.
- Secure remote access (OpenVPN) and a continuous integration pipeline for internal applications.
- Shared web and VPS hosting (Plesk, WHMCS), with automated provisioning in Python.
Fullstack and DevOps intern
Nobo (Palladium group)
Internship, Boulogne-Billancourt- Set up automated, tested deployments with Bitbucket and Jenkins.
- Deployed an ELK stack to centralize and analyze application logs.
- Dockerized the microservices and added SonarQube to the quality pipeline.
- Vulnerability audits (OpenVAS) and remediation.
Skills
Tools I use
- Front-end, mobile and desktop
- TypeScriptReactNext.jsReact NativeExpoFlutterSwiftUIRust / TauriTanStack QueryRedux ToolkitTailwind / NativeWindMantine UI
- Back-end
- Node.jsNestJSExpressPHPPythonJava (Spring, Vaadin).NET (ASP.NET Core)RESTGraphQLOpenAPIRabbitMQPub/SubPostgreSQLMySQLPrismaSQLite
- CMS and e-commerce
- Sitecore XP / SXAPayload CMSWordPressPrestaShop
- DevOps and cloud
- DockerKubernetes (GKE, AKS)Argo CDAnsibleKamalGitHub ActionsGitLab CIJenkinsBitbucket PipelinesAzure PipelinesAWSAzureGoogle CloudOVHOpenStackCloudflareTraefik
- Systems and monitoring
- Linux (Debian)BashOpenVPNTailscaleELKLoki / GrafanaTelegrafSentryCloudWatchOpenVAS
- Testing and quality
- PlaywrightDetoxSeleniumSonarQube
- Applied AI
- Claude CodeAI agentsMCPOllamaLLM orchestration
Projects
Side projects
career-hub
LLM-generated targeted resumes, rendered to PDF with Typst, with semantic search on pgvector.
LLM, Typst, pgvector
Agent orchestration kanban
Tauri desktop app to run several Claude Code sessions from a kanban board.
Tauri, Claude Code
Éclore
iOS app that helps people quit smoking and cannabis, designed to never shame the user.
SwiftUI, SwiftData
Appwrite Exceptions Translator
NPM package that turns Appwrite's technical error messages into clear, actionable explanations.
TypeScript, Bun, Appwrite
10K Step Path Generator
Loop walking-route generator for a daily step goal, with a Leaflet map, GPX export and local storage.
Next.js, Leaflet, Bun
Sports Events
Web platform for local sports events: creation, sign-up, geolocation and mapping.
React, Next.js, Spring Boot, MySQL
Whats The Weather
Real-time weather forecast iOS app, inspired by the Weather app, built in SwiftUI with OpenWeatherMap data.
Swift, SwiftUI, OpenWeatherMap
Self-hosted AI infrastructure
Local inference with Ollama on a GPU, routed over Tailscale, with services deployed through Dokploy behind Cloudflare Tunnel.
Ollama, Tailscale, Dokploy, Cloudflare
Education
Education and languages
- Master of Science, Software architect, application developer
ETNA, Paris, 2024 - Bachelor's degree, Web and mobile project manager
ETNA, Paris, 2022 - Engineering programme, Automated systems
ESSTI, Rabat, 2019 - Preparatory classes, Mathematics, physics and mechanics
ESSTI, Rabat, 2018
- French, fluent
- English, professional, TOEIC 925/990
Interests
Away from the keyboard
Hiking · Reading · Art · Photography · Car tuning · Electronics and home automation