Full-stack engineer. Psychology background.
Currently at Amber Electric, on the OEM team.
~/now
Building integrations between OEMs and SmartShift at Amber Electric. Before that: three and a half years on identity and support automation for Cash App at Block, serving tens of millions of users. The thread across roles is instrumentation — I build the feedback loops that tell me whether a system is well.
~/selected-work
Setlister.xyz
A side project I designed, built, deployed and maintain entirely on my own — from first line of code to production infra. Musicians paste in their repertoire and venue context; Setlister plans a coherent set with tempo and key flow, energy arcs, and transitions that actually work on stage. Built because I play in bands and hated cobbling sets together the night before a gig.
~/other-projects
Guardian CDK↗~/writing
~/off-hours
the non-code
artefacts
Stephen Geller
Scaled identity verification for millions at Cash App. Built The Guardian's org-wide metrics platform. Now contracting at Amber Electric on OEM ↔ SmartShift integrations for household energy shifting.
present
Full-Stack Engineer (Contract)
Building integrations between OEMs and SmartShift on the OEM team — enabling intelligent energy management for connected devices.
Nov 2025
Software Engineer
Led backend development for customer identity verification and support automation, serving tens of millions of Cash App users.
- Built Tap to Confirm — in-app confirmation flows + MFA verifying millions of identities
- Drove org-wide SLO adoption via deployment-drift monitors used across multiple teams
- Built advocate tooling: PII verification, case management, customer search
May 2022
Software Engineer (Contract)
Frontend on Shop Experience — e-commerce features and BFF ↔ Contentful delivery.
Aug 2021
Software Engineer
Developer experience and observability across the Guardian's digital department.
- Centralised observability — built org-wide metrics platform on Grafana + Elasticsearch + CloudWatch
- Authored Guardian CDK library adopted across teams
- Built Cypress integration-test service monitoring key user journeys
Aug 2019
DevOps Engineer
Kubernetes infra + Prometheus/Alertmanager monitoring.
May 2019
Software Developer
Shared Infrastructure. XP + Agile. Led code dojos.
languages
Kotlin
JavaScript
Ruby
Python
SQL
infra
CDK · Kubernetes · Docker
Terraform · CI/CD
observability
Prometheus · Elasticsearch
CloudWatch · PagerDuty
BSc Psychology (First Class Honours)
Software Development Bootcamp
12 weeks, TDD + pair programming + Agile.