Guillaume Berthet
Built with agents. Not full of agents.
The method is agentic: supervised runs, guardrails enforced outside the model, evidence before every handover. The deliverable is plain, reliable software — business integrations and internal tools running in production, with dates, that your own team can take over.
01
What runs in production
Four systems delivered to clients, with their dates. No performance figures are shown here: the ones I could quote are neither dated nor measured, so they are not published.
- In production since 17/03/2026
Chauvet79 — email → HubSpot
Middleware that intercepts Esabora and Hercule Pro documents arriving by email, matches them to the right contact and deal, and files the PDF in HubSpot. Silent failures raise an alert instead of being swallowed.
- TypeScript
- HubSpot API
- IMAP
- Dokku
- In production since 06/05/2026
L'EXPRESSIONIST — Shopify B2B × HubSpot
Middleware between the B2B Shopify store and HubSpot: accounts, orders and sales follow-up synchronised with no re-keying, with an automatic check after every deployment.
- TypeScript
- Shopify API
- HubSpot API
- Running since 2025
ChefCheffe — HelloHarel ERP ↔ HubSpot
Bidirectional middleware between the HelloHarel ERP and HubSpot, under continuous monthly maintenance. Last fix shipped 21 August 2026 — a living system, not an archived reference.
- TypeScript
- HubSpot API
- ERP HelloHarel
- Deployed — 2A training 15/09/2026
2A — fieldkit, the offline visit report
Offline-first field PWA replacing the paper maintenance-visit report, with write-back into HubSpot. Signed 17 August 2026, deployed to production infrastructure since 21 August 2026. The 2A team training is on 15 September 2026: as of today it has not happened, so the system is not yet in field use. It is the only one of the four in that state, and it is listed here with that caveat rather than without it.
- TypeScript
- PWA
- IndexedDB
- HubSpot API
These four systems are client work — invoiced and maintained. My own products — a chatbot platform, a multi-tenant agent backend — run on the same infrastructure and serve as the test bench for the method. They are not the offer, and they are not the reference.
02
How I work
Four rules, applied to every project above.
Async-first
Writing is the default medium: decisions, trade-offs and reports live in the repository, not in a call. We talk when it is useful, not to fill a calendar — and you keep the record.
Discovery comes first
The problem is established and written down before the first line of code: the scope, what is explicitly out of it, and how we will know it is finished. That is where projects are won, and it is where I spend the most time.
Evidence, not impressions
Agents execute, guardrails decide: automatic checks before every commit, a frozen set of real cases replayed on every change, a dated record of what shipped. “It worked when I tried it” is not a delivery state.
Long missions: the door is open
I am open to multi-month or fractional architect missions, remote-first. On-site presence is valuable at the start — meeting the teams, learning the ground, auditing what exists — and I travel for it gladly. What does not work is a standing on-site obligation written into the contract.
03
2 million downloads on my first app taught me: technical success ≠ business success.
Today I help businesses build the right thing the first time.
04
How I can help
Build and ship the system
From scoping to production, then maintenance. Integrations, middleware and internal tools — built with agents, delivered as plain software your own team can take over.
Audit Your Processes
Find where automation saves you time and money — and where it has no business being. No buzzwords, just honest analysis.
Ongoing Partnership
Long-running support for teams that need a senior architect on call without hiring one.
Ready to avoid costly mistakes?
Let's discuss your project. 30 minutes to understand your needs and see if I can help.
Or send me an email: guillaume@gbconsult.me