Full-stack developer building side projects alongside enterprise work — B2B SaaS, iOS native apps, and browser-native creative tools.
Swift · TypeScript · React · Node.js
CoreBluetooth app targeting the standard Heart Rate GATT profile (0x180D). Live BPM with 5-zone colour coding, rolling RMSSD / SDNN / pNN50 HRV from RR intervals, calorie estimation via Keytel 2005 formula, session recording with SwiftData persistence, and Apple Health write via HKWorkoutBuilder. Screen idle timer disabled during active sessions.
Swift SwiftUI CoreBluetooth HealthKit SwiftData
Maps informal influence networks inside organisations from engagement data — meetings, emails, Slack. Scores relationships across engagement depth, organisational proximity, and interaction recency to surface decision-makers and flag where relationship risk is building. Claude-powered analysis layer turns fragmented CRM data into a live influence map with prioritised actions.
React Node.js PostgreSQL Claude API
Browser-native canvas tool for generating high-fidelity gradient compositions. Layered control over colour palettes, bias curves, blend modes, and geometric multipliers. Real-time HTML Canvas rendering with undo/redo history, curated presets, and SVG/PNG export.
React TypeScript HTML Canvas
Cross-references IKEA product package dimensions — scraped live via Firecrawl — against cargo specs for any car make, model, and year. Returns a package-by-package fit verdict with volume breakdowns and multi-car comparison before you leave the house.
React Supabase Edge Functions Firecrawl
Tracks birthdays across your social circle, drafts personalised messages ahead of time, and delivers via the contact's preferred channel — WhatsApp, SMS, email, or Messenger. Weekly home screen calendar surfaces who's coming up; monthly overview gives the full picture.
React TypeScript Tailwind CSS
More at janrenfordt.com