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Full-stack software engineer and founder of HAM Studio (_Website not available. Sign in: https://www.twine.net/signup_ with over 15 years building production web applications, from enterprise platforms for major UK banks and retailers to modern AI products. Equally comfortable owning architecture and shipping code, Julien's recent work focuses on RAG pipelines, multi-model LLM integration, and multi-tenant SaaS on a TypeScript/Next.js/Supabase stack, known for thorough scoping, calm stakeholder delivery, and on-time releases. Recent client work includes Stripe subscription billing (plans, webhooks, customer portal) and admin dashboards with analytics. AI API integration (OpenAI, Anthropic) in multi-tenant SaaS is his day-to-day, most recently the RAG work for Versey.…Full-stack software engineer and founder of HAM Studio (_Website not available. Sign in: https://www.twine.net/signup_ with over 15 years building production web applications, from enterprise platforms for major UK banks and retailers to modern AI products. Equally comfortable owning architecture and shipping code, Julien's recent work focuses on RAG pipelines, multi-model LLM integration, and multi-tenant SaaS on a TypeScript/Next.js/Supabase stack, known for thorough scoping, calm stakeholder delivery, and on-time releases. Recent client work includes Stripe subscription billing (plans, webhooks, customer portal) and admin dashboards with analytics. AI API integration (OpenAI, Anthropic) in multi-tenant SaaS is his day-to-day, most recently the RAG work for Versey.

Julien Mandart

Full Stack Developer, Software Engineer, AI Developer, +4

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Full-stack software engineer and founder of HAM Studio (_Website not available. Sign in: https://www.twine.net/signup_ with over 15 years building production web applications, from enterprise platforms for major UK banks and retailers to modern AI products. Equally comfortable owning architecture and shipping code, Julien's recent work focuses on RAG pipelines, multi-model LLM integration, and multi-tenant SaaS on a TypeScript/Next.js/Supabase stack, known for thorough scoping, calm stakeholder delivery, and on-time releases. Recent client work includes Stripe subscription billing (plans, webhooks, customer portal) and admin dashboards with analytics. AI API integration (OpenAI, Anthropic) in multi-tenant SaaS is his day-to-day, most recently the RAG work for Versey.…Full-stack software engineer and founder of HAM Studio (_Website not available. Sign in: https://www.twine.net/signup_ with over 15 years building production web applications, from enterprise platforms for major UK banks and retailers to modern AI products. Equally comfortable owning architecture and shipping code, Julien's recent work focuses on RAG pipelines, multi-model LLM integration, and multi-tenant SaaS on a TypeScript/Next.js/Supabase stack, known for thorough scoping, calm stakeholder delivery, and on-time releases. Recent client work includes Stripe subscription billing (plans, webhooks, customer portal) and admin dashboards with analytics. AI API integration (OpenAI, Anthropic) in multi-tenant SaaS is his day-to-day, most recently the RAG work for Versey.

Available to hire

Full-stack software engineer and founder of HAM Studio (Website not available. Sign in: https://www.twine.net/signup with over 15 years building production web applications, from enterprise platforms for major UK banks and retailers to modern AI products.

Equally comfortable owning architecture and shipping code, Julien’s recent work focuses on RAG pipelines, multi-model LLM integration, and multi-tenant SaaS on a TypeScript/Next.js/Supabase stack, known for thorough scoping, calm stakeholder delivery, and on-time releases.

Recent client work includes Stripe subscription billing (plans, webhooks, customer portal) and admin dashboards with analytics. AI API integration (OpenAI, Anthropic) in multi-tenant SaaS is his day-to-day, most recently the RAG work for Versey.

Skills

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Work Experience

Lead engineer · Knowledge Bases & RAG platform at HAM Studio (Versey)

January 1, 2026 - January 1, 2026

Designed and built the Knowledge Bases feature for an AI writing partner. Chose a single RAG pipeline across multiple model providers (Claude, GPT, Gemini, Perplexity) and implemented ingestion, background retries, citations, and visible source grounding. Built the pipeline using Mastra with pgvector inside the client’s existing Supabase Postgres (single DB/shared backups). Implemented infrastructure-level multi-tenant isolation by enforcing a Knowledge Base filter on all vector queries plus pre-agent auth checks to prevent cross-tenant leakage. Shipped from kickoff to production in one week.

Lead engineer · Web application & infrastructure at HAM Studio (Podback)

January 1, 2021 - Present

Built and operate the web application and infrastructure behind a UK recycling scheme backed by coffee brands. Delivered a data model and decision engine to route users to the correct recycling route based on machine/pod brand and postcode across varying local authority rules. Implemented API development, custom authentication, admin dashboard, security, monitoring, and seamless integration with e-commerce fulfilment for kit ordering. Scaled nationwide as new local authorities and coffee brands joined, with ongoing engagement.

Lead engineer · SEO & front-end optimisation at HAM Studio (Pebble)

January 1, 2020 - December 31, 2020

Led a critical SEO and website optimisation initiative, coordinating multiple stakeholders and delivering SEO upgrades ahead of schedule. Combined front-end implementation expertise with solutions-focused project leadership to manage uncertainty and exceed expectations.

Embedded software engineer at HAM Studio (Plum Guide)

January 1, 2020 - December 31, 2020

Integrated into Plum Guide’s in-house design and development team for a 2020 platform redesign. Resolved the tension of high-imagery luxury assets by improving performance through image compression, lazy-loading, caching and CDN. Ran A/B tests across design variations and iterated through to launch.

Embedded software engineer · Redesign & performance at HAM Studio (Plum Guide)

January 1, 2020 - January 1, 2020

Integrated into Plum Guide’s in-house design and development team for their 2020 platform redesign. Resolved performance vs. high-imagery trade-offs by reducing load times using image compression, lazy-loading, caching and CDN. Ran A/B tests across design variations and iterated to launch.

Senior Software Engineer Consultant at Trussle

May 1, 2019 - December 1, 2019

Lead engineer · SEO & front-end optimisation at HAM Studio (Pebble)

January 1, 2019 - January 1, 2019

Led a critical SEO website optimisation project, coordinating multiple stakeholders and delivering the full suite of SEO upgrades ahead of schedule. Combined front-end development with solutions-focused project leadership to navigate uncertainty calmly and exceed expectations.

Software Engineer Consultant at Trainline

September 1, 2018 - May 1, 2019

Software Engineer Consultant at Barclays

June 1, 2018 - August 31, 2018

Lead Software Engineer Consultant at Pearson

November 1, 2017 - May 1, 2018

Lead / Software Engineer Consultant at Lloyds Banking Group

October 1, 2017 - June 1, 2018

Lead / Software Engineer Consultant at Royal Bank of Scotland

March 1, 2015 - October 1, 2016

Developer (Contract) at AnalogFolk

September 1, 2013 - September 1, 2013

Interactive Developer (Contract) at Burberry

September 1, 2013 - March 1, 2015

Developer (Contract) at Havas Work Club

July 1, 2013 - August 31, 2013

Technical Consultant at BIG DB

January 1, 2013 - June 1, 2013

Founder & Principal Engineer at HAM Studio

January 1, 2013 - Present

Founded and run a software engineering studio delivering web, e-commerce and AI products for clients including Versey, Podback, Plum Guide, Eversys and Pebble. Led scoping, architecture and hands-on delivery across the full stack, with emphasis on delivery planning, multi-tenant/security considerations for SaaS, and shipping production systems.

Developer at Pirate

March 1, 2012 - January 1, 2013

Prototyped, scoped and developed innovative projects including the McLaren Racing website and live telemetry dashboard, and the British Olympic Association (Team GB) live application.

Developer at Pirata

March 1, 2012 - January 1, 2013

Prototyped, scoped and developed innovative projects including the McLaren Racing website and live telemetry dashboard, and the British Olympic Association (Team GB) live application.

Full Stack Developer at IPC Media

February 1, 2010 - April 1, 2012

Web Developer at Environmental Business Products

February 1, 2009 - January 1, 2010