gb-coding.nl
Portfolio

Selected work.

A small, representative selection. Reach out for case studies and references.

SaaS Analytics Dashboard
Next.js · Postgres · Kotlin

SaaS Analytics Dashboard

Multi-tenant analytics with real-time charts and role-based access.

Outcome

Replaced a CSV-export workflow with live dashboards. Cut weekly reporting overhead from ~6 hours to near-zero and unlocked a new self-serve tier.

  • Next.js App Router
  • Kotlin Ktor API
  • Postgres + Row-Level Security
  • Recharts
Booking System
Spring Boot · Postgres

Booking System

End-to-end reservation platform with payments and calendar sync.

Outcome

Handled overlapping availability, refunds, and ICS calendar sync without double-bookings during launch week. Stripe webhooks idempotent end-to-end.

  • Spring Boot
  • Postgres
  • Stripe Checkout
  • iCal feed
E-commerce Backend
Ktor · Mongo · Stripe

E-commerce Backend

Headless commerce API powering web and mobile storefronts.

Outcome

One API serving Next.js storefront and a native mobile app. P95 latency under 120ms on cached product reads, full Stripe + tax integration.

  • Ktor
  • MongoDB
  • Stripe Connect
  • CDN-cached product API
AI-Generated Marketing Sites
Lovable · 24–72h

AI-Generated Marketing Sites

Productized marketing sites delivered in days for early-stage teams.

Outcome

30+ sites shipped with SSR meta, JSON-LD, sitemap, and analytics out of the box. Same-week delivery from brief to live URL.

  • Lovable
  • TanStack Start
  • Tailwind
  • Cloudflare hosting
Mobile Field App
Kotlin Multiplatform

Mobile Field App

Offline-first iOS + Android app for technicians in the field.

Outcome

Shared 80% of business logic across platforms. Sync queue survives no-signal job sites and reconciles on reconnect without duplicates.

  • Kotlin Multiplatform
  • Compose Multiplatform
  • SQLDelight
  • Ktor client
Internal Admin Tool
Next.js · Postgres

Internal Admin Tool

Custom CRUD console replacing 5 spreadsheets and a Jira board.

Outcome

Consolidated tribal-knowledge spreadsheets into a single typed admin with audit trail. Onboarding time for new ops hires dropped from days to hours.

  • Next.js
  • Postgres
  • shadcn/ui
  • Audit log table

Start your project today.

Tell me about what you're building. I'll come back with a free estimate within 24 hours.