Gabriel Mustiere
Gabriel Mustiere
Portrait of Gabriel Mustiere
Freelance
CTO

Tech · Business · AI. Nantes — remote.

Background
FR EN
Background

Freelance CTO.
Symfony & Sylius expert.
Based in Nantes.

Developer Symfony since 2012, CTO since 2017. My craft: building SaaS and e-commerce products from scratch, from early-stage MVPs to scaling multiple teams.

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§ 01

Experience

  1. Sept 2025 → present

    Anytime — WebAuthn & PSD2 Lead

    Digital bank · Symfony · banking security
    • Strong Customer Authentication (PSD2) compliance with WebAuthn
    • Passkey, biometric integration
    • Cross-team coordination with product, compliance and platform
  2. 2022 → 2025

    Passion Barbecue — Co-founder & CTO

    Premium e-commerce · Sylius

    Co-founded Passion Barbecue. As founding partner and CTO, I drove the product's technical vision: design and ownership of the Sylius e-commerce architecture, focused on robustness, scalability, and integration across the logistics, marketing and editorial stack.

    • E-commerce core: build on Sylius (Symfony) with extensions and business features tailored to specialised retail
    • Logistics & marketplaces: BoostMyShop integration (orders, stock, shipping) and Sellermania (product feeds, orders, statuses)
    • Search & content: Meilisearch for product search, headless Directus + CDN architecture for editorial management decoupled from the back office
    • CI/CD & CRM: GitLab pipelines, Mailjet for transactional emails and marketing campaigns
  3. 2017 → 2023

    Progicar / Groupe GEMY — Founding CTO

    B2B SaaS subsidiary · Symfony · 0 → 20+ people

    First technical hire at Progicar, a SaaS subsidiary built from scratch inside Groupe GEMY (car dealership network). Strategic mission: turn the group's legacy in-house apps into a modern SaaS platform — first for internal use, then commercialised to third-party players in the automotive distribution sector.

    • Strategy & architecture: tech strategy and target architecture, stack standardisation (frameworks, automated tests, CI/CD, tooling), engineering culture geared towards quality, testability and observability
    • Stack: Symfony, API Platform, VueJs, Docker, CheckMK, Scaleway
    • Engineering 0 → n: hired and structured 20+ people across 3 cross-functional product teams (PO, Lead Devs, Devs) + transverse functions (SRE/infra, design, marketing)
    • Operational leadership: 5 years running Progicar alongside the group's support functions (Finance, HR, Legal, IT); refocused on engineering and product when a commercial CEO joined
  4. 2013 → 2017

    XL Soft — Web developer & NF 525 certification lead

    Retail software vendor · PHP · NF 525 / AFNOR

    At XL Soft (point-of-sale and retail management software vendor), I first designed and built web applications for retail players, then took the lead on the NF 525 compliance programme for the XL POS solution, all the way to AFNOR certification in January 2017.

    • NF 525 lead: AFNOR specification analysis, project planning, Squash TM rollout for the test strategy, final audit
    • XL Analytics: full design and build of a Business Intelligence app to steer retail network performance
    • Vente accompagnée: rebuilt the product catalog with a responsive UI optimised for in-store tablet use
    • Industrial thesis (Information Systems Manager title) on the reliability of production applications: software quality, incident management, observability
§ 02

Expertise

Symfony — since 2012

14 years of practice on Symfony, from 2.x to 7.x. Doctrine ORM, Messenger, API Platform, forms, security, events, command buses. Able to audit an existing Symfony codebase, define an LTS migration strategy, train a team, or start a project from scratch with the right calls on day one.

Sylius — bespoke e-commerce

Designed and operated a Sylius platform in production on Passion Barbecue. Custom catalog, checkout, payment, marketing and logistics integrations. Sylius is my e-commerce framework of choice when the business need outgrows Shopify: configurable products, business-specific taxonomies, custom purchase paths, tailored back office.

Product builder — 0 → 1 and 1 → n

From zero to first customer, then from first customer to multiple teams and thousands of users: I've walked that path twice, on Progicar (B2B SaaS) and Passion Barbecue (e-commerce).

Early on, that means picking a stack you can live with, shipping an MVP fast without painting yourself into a corner, and knowing which technical debt you take on deliberately rather than by accident. As the product grows, it means structuring teams, industrialising what used to be patched together, and handing off the topics a single founder can no longer carry.

Concretely useful for:

  • early-stage startups looking for a founding or fractional CTO to frame their first technical choices;
  • non-technical founders who want to avoid the classic first-MVP pitfalls;
  • teams that shipped an MVP and aren't sure how to scale up without a full rewrite.

Architecture & technical leadership

  • Evolutive architecture: hexagonal, light DDD, modular monolith before microservices
  • DevOps: CI/CD industrialisation, progressive delivery, monitoring
  • Hiring and structuring teams from 5 to 25 people
  • Product-tech framing, business alignment, debt vs. velocity trade-offs

Security & compliance

  • WebAuthn / passkeys / biometrics / hardware keys
  • PSD2 / SCA (Strong Customer Authentication)
  • RGPD (personal data, sub-processors, consent)
§ 03

How I work

Long engagement (3-12 months)

Technical lead on a structuring project, embedded in your team. Current format with Anytime.

Fractional CTO — early-stage startup

1 to 3 days a week, alongside a non-technical founder or a junior team. To go from MVP to first traction without hiring a permanent CTO too early.

Audit (1-3 weeks)

Codebase, architecture or tech-organisation audit. Written deliverable with prioritised recommendations and a live debrief.

Sparring partner

Regular sessions (1h/week or 1/2 day a month) to challenge your tech and product decisions. For founders or incumbent CTOs who want an outside perspective.

§ 04

Location & availability

Based in
Nantes (44)
Remote
France · Europe
On-site
Nantes · Paris occasionally
Availability
Q3 2026
Email
mustiere.gabriel@gmail.com
LinkedIn
gabrielmustiere
§ 05

FAQ

Why a freelance CTO rather than a permanent CTO?
For phases where the team doesn't justify a full-time hire (early stage, transition, audit), a freelance CTO delivers the expertise without freezing a permanent seat. And on focused long engagements (compliance, scale-up, rewrite), a senior freelance reaches the target faster than a hire.
What sets a Symfony expert apart from a senior Symfony developer?
A senior writes good code. An expert factors in ecosystem debt (LTS versions, Symfony 6 → 7 upgrade, Doctrine and API Platform dependencies), arbitrates long-term architectural choices, and can read / refactor an existing codebase without breaking everything.
Do you work with stacks other than Symfony and Sylius?
I work primarily with Symfony and its ecosystem (Doctrine, API Platform, Sylius). On the front-end side, I also have experience with Vue.js and Nuxt. On an engagement, the product context and team usually matter more than the exact language.
Do you take co-founder / equity engagements?
I'm open to any honest, well-thought-out proposal.
How much does an engagement cost?
Day rate aligned with senior freelance CTO market in Nantes / remote. Fixed fees possible for audits. We discuss it after a first call to frame the need.
Why Nantes?
I live here. The Nantes tech ecosystem is dense (Lengow, iAdvize, Akeneo, Manzana…) with a real Symfony / PHP community. Most of my engagements run remote or hybrid.
§ 06 · Next?

Let's talk.

Long engagement, fractional, audit or sparring: a single email is enough. Response within 48h.

Write an email →