FREN

HelloSalut

I'm Hermann Kao

Fullstack JavaScript / TypeScript developer with a DevOps focus

I have been building web and mobile apps in TypeScript since 2020, and I also take care of what runs underneath: CI/CD, Kubernetes, AWS and monitoring. I have often been the only engineer on a product, covering the backend, the mobile app and the infrastructure. Since 2025 I have been wiring AI agents into delivery pipelines, from the ticket to a tested pull request.

Saint-Étienne, France. Hybrid in Saint-Étienne or fully remote.

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Portrait of Hermann Kao

Work

My path

Assignments that overlapped sit on parallel branches.

  1. Application integrator and DevOps engineer

    B2B equipment financing company (financial group)
    Freelance (umbrella company), Saint-Étienne

    Part 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.

  2. 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).
    • Set up automated CI/CD deployment for a Flutter application.
    • Contributed to an internal AI agent orchestration project.
    • Built a local WordPress development toolkit (Makefile, MCP skills, agent commands).

  3. Mobile developer, then fullstack developer, then software architect

    The After Cancer, health support app (Portugal)
    Freelance, Remote

    Hired 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.

    • 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.
    • Ephemeral review environment created on AWS for each pull request, removed after 3 days.

  4. Freelance developer

    Short assignments for startups and studios
    Freelance

  5. Fullstack and DevOps developer

    Nobo, home cleaning service (Palladium group)
    Work-study, then freelance, Boulogne-Billancourt

    • Moved deployments to Argo CD on GKE and managed Google Cloud and OVH servers.
    • Migrated two React Native apps from an Expo 52 monorepo to two independent Expo 57 apps with a hexagonal architecture.
    • Offline SQLite outbox so that service validation, which triggers billing, survives poor connectivity.

  6. System administrator

    Snowtrust (Limoges)
    Freelance

  7. Fullstack and DevOps intern

    Nobo (Palladium group)
    Internship, Boulogne-Billancourt

    • Set up automated, tested deployments with Bitbucket and Jenkins.

Skills

Tools I use

Front-end and mobile
TypeScriptReactNext.jsReact NativeExpoFlutterSwiftUI
Back-end
Node.jsPHPPython.NETRESTRabbitMQPub/SubPostgreSQLMySQL
CMS and e-commerce
Sitecore XP / SXAPayload CMSWordPressPrestaShop
DevOps and cloud
DockerKubernetes (GKE)Argo CDGitHub ActionsGitLab CIJenkinsAWSGoogle CloudOVHCloudflare
Systems and monitoring
Linux (Debian)BashELKLoki / GrafanaSentryCloudWatch
Applied AI
Claude CodeAI agentsMCPOllamaLLM orchestration

Projects

Side projects

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
  • French, fluent
  • English, professional, TOEIC 925/990