GUILLAUMEBAILLEUL

Services

Focused independent engagements for teams that need senior-level Elixir, React, or technical leadership without the overhead of a full-time hire.

Discuss your project
Concurrent, fault-tolerant systems at scale

Elixir / Phoenix Backend

Design and build production-grade backends with Elixir, Phoenix, and OTP. Real-time features with LiveView, event-sourcing architectures, and integration with third-party APIs or legacy systems.

  • Phoenix API or LiveView application
  • OTP supervision trees and fault tolerance
  • PostgreSQL schema design and Ecto queries
  • Performance profiling and optimisation
  • CI/CD pipeline setup
Fixed-price missionDaily ratePart-time retainer
Scalable, maintainable user interfaces

React / TypeScript Frontend

Build high-quality SPAs, Next.js applications, and component libraries with React and TypeScript. Focus on performance, accessibility, and long-term maintainability.

  • Next.js or React application
  • TypeScript-first codebase
  • Component design system
  • Testing strategy (unit + integration)
  • Lighthouse performance audit
Fixed-price missionDaily ratePart-time retainer
End-to-end delivery, from design to production

Full-Stack Application

Own the full delivery of a product: backend API, frontend application, deployment, and monitoring. Ideal for startups that need a senior engineer who can operate autonomously.

  • Full-stack architecture design
  • Backend + frontend development
  • Deployment on cloud infrastructure
  • Monitoring and alerting setup
  • Documentation and handoff
Fixed-price missionDaily rate
Technical leadership without the hiring overhead

Tech Lead on Demand

Embed as a part-time or interim Tech Lead in your team. Architecture decisions, code reviews, mentoring, and bridging technical and product discussions.

  • Architecture decision records (ADRs)
  • Weekly code & architecture reviews
  • Team mentoring and pair programming
  • Technical roadmap and prioritisation
  • Stakeholder-facing technical summaries
Part-time retainer (2–3 days/week)Advisory retainer
An outside eye on your system

Architecture Audit

A focused, time-boxed review of your codebase or architecture. Identify bottlenecks, technical debt, security gaps, and scalability risks. Delivered as an actionable written report.

  • Codebase & architecture review
  • Bottleneck and risk identification
  • Prioritised written recommendations
  • 1-hour debrief call
  • Optional 30-day follow-up Q&A
Fixed price (1–2 weeks)
Migrate without breaking production

Legacy Modernisation

Incremental migration of legacy systems (PHP, Ruby, monoliths) towards modern, maintainable architectures. Done in production at scale, with zero downtime.

  • Migration plan and risk assessment
  • Strangler-fig pattern implementation
  • Test coverage improvements
  • Parallel-run validation
  • Knowledge transfer to your team
Fixed-price milestoneDaily rate

How it works

01

Send a brief

Describe your project, timeline, and expectations via the contact form. Takes 5 minutes.

02

Discovery call

30-minute call to understand your context, constraints, and goals.

03

Proposal

I send a written proposal with scope, timeline, rate, and terms within 48 hours.

04

We start

Kick-off, onboarding, and regular async updates throughout the mission.

Ready to start?

Tell me what you're building. I'll get back to you within 24 hours.

Send a brief