Lenny Daume
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LGE Energy Berlin GmbH // Zenstrom Logo

LGE Energy Berlin GmbH // Zenstrom

100% Remote / Berlin

Website and Service Portal for Zenstrom

Freelance Fullstack Developer & Consultant

June 2023 - December 2023
7 months
Freelance
Project work
100% Remote / Berlin

Relevance

Why this case matters

The case shows how problem understanding, responsibility, decisions, and implementation came together in this context.

Impact

Independently built and operated the website and service portal with Astro, React/Svelte, PWA, Lumenaza API, auth, ArangoDB, AWS SNS, Woodpecker CI, tests, and operations.

What carries forward today

AI-native systems craft needs clean web, data, and integration boundaries. This work strengthened the foundations that later automation can build on; in parallel I used LLM-assisted development (ChatGPT) in daily work, as far as the 2023 models were already dependable for it.

WebsiteService PortalPWAProduct engineeringEnd-to-end deliveryCI/CDOperationsLumenaza APILLM-assisted development

Defensible proof

2 products

Website + service portal

Built and operated the public website and authenticated customer portal as separate Astro codebases.

Auth + API

Portal functions

Connected password flow, customer data, invoices, meter readings, and the Lumenaza API into a usable portal.

CI/CD

Operations

Woodpecker CI, tests, monitoring, and deployments as part of product work.

Where this experience creates value

  • For teams that treat modern web and portal architecture as more than a frontend topic.
  • For product organizations that want technical choices connected early to delivery and operations.

Case context

Overview

Zenstrom needed more than a marketing website. It needed a usable service portal for real customer workflows. I independently built and operated the public website and authenticated service portal as two Astro products with React/Svelte, PWA capabilities, ArangoDB, the Lumenaza API, and AWS SNS.

The important part was connecting product surface, integrations, delivery, and operations: tariff calculator, registration, login, password flow, customer data, invoices, meter readings, and portal communication had to work together reliably. Woodpecker CI, Vitest, Cypress, Ackee, Bugsnag, and clear deployments kept quality and runtime behavior visible.

Responsibility

Activities

  • Website: Astro SSR/CSR, tariff calculator, registration flow, SEO, sitemap, robots.txt, and performance work
  • Service portal: Auth flow, password reset, customer data, invoices, meter readings, and active contract checks
  • Integrations: Lumenaza API, ArangoDB, AWS SNS, Slack notifications, Ackee analytics, and HubSpot-adjacent flows
  • Operations: Woodpecker CI, staged deployments, Traefik, monitoring, error notification, and portal noindex rules
  • Built-in quality: Vitest, Cypress E2E, form validation, API error handling, and security-relevant password hashes with Argon2
  • Test-first product development: frequently used Cypress as the working browser to specify, run, and debug portal and signup behavior directly while building
  • LLM-assisted development: used ChatGPT early in daily work for research, code reviews, and copy, as far as the models of that time were already dependable for it

Operating mode

Methodology

  • Product and operations together: Treat website, service portal, API integration, and deployment as one product system
  • Kanban as a visibility model: Keep work, blockers, and next decisions inspectable
  • Built-in quality: Bring tests, Cypress as a working and test browser, performance work, password hashing, error handling, and noindex rules into delivery early
  • Keep architecture decisions small: separate codebases, clear portal boundaries, and direct integrations only where they carry product value
  • Knowledge transfer: Treat documentation, maintenance recommendations, and client training as part of handover readiness

Technical context

Technology stack

The tools are not the point by themselves. What matters is which system layers had to work together.

9Areas
46Technologies

DevOps

5
GitTraefikMonitoringBugsnagPlatform Operations

Frontend

11
Tailwind CSSAstro (SSR & CSR)ReactSvelteTypeScriptJavaScriptPWAWorkboxProgressive Web AppsAuth AstroECharts

Tools

7
ViteVitestCypressHubSpotn8nSlackIntegration Tools

Practices

7
Test-Driven DevelopmentAgile TestingShift-left QualityTestingQuality AssuranceProduct EngineeringEnd-to-End Delivery

Databases & Storage

5
AWS S3AWS RDSPostgreSQLMariaDBArangoDB

Messaging & Event Streaming

1
AWS SNS

Backend

6
Lumenaza APIREST APIsArgon2MJMLNodemailerAxios

CI/CD & Delivery Pipelines

2
Woodpecker CICI/CD Pipeline

Data & AI

2
AckeeLLM-assisted Development

Next step

If you need similar responsibility, we can identify the next useful leverage point directly.

Send the situation, goal, and decision in front of you. I will respond personally with a clear view of the value I could add.

Discuss the next leverage point