Dino Fancellu
Felstar Ltd · Contract senior engineer

Dino Fancellu

Senior engineer, shipping software since 1986. Scala, TypeScript, Python and LLM tooling today; C, C++ and plenty of Java before that. I build backends, full-stack products and AI features, and I pick up whatever the job needs.

  • Outside IR35
  • 100% remote
  • Epsom, UK
Portrait of Dino Fancellu
Clients include
  • Brevan Howard
  • JPMorgan Chase
  • HSBC
  • Barclays
  • Thomson Reuters
  • Fitch Ratings
  • Standard Bank
  • UniCredit
  • ClearScore
  • HMRC
  • The Guardian
What I do

Many hats, one standard.

Backend, front end, data, integration, AI and tech lead: I’ve done most of it, in most of the languages that mattered at the time. What doesn’t change is functional thinking, small sharp code and finishing what I start.

01

AI & LLM tooling

RAG, embeddings and vector search, MCP servers, agent pipelines and LLM features in production, across Claude, Gemini, OpenAI and local models.

  • RAG
  • LanceDB
  • ChromaDB
  • MCP
  • PocketFlow
  • LangChain
  • Hugging Face
  • PyTorch
  • Gradio
  • Claude Code
02

TypeScript, full stack

Modern web products end to end: React and Next.js in front, Bun or Node with Elysia behind, deployed to the edge.

  • TypeScript
  • React
  • Next.js
  • Bun
  • Elysia
  • Vite
  • Cloudflare Workers
  • Tailwind
  • Drizzle
  • TanStack
  • Svelte
03

Scala & the JVM

Typelevel and ZIO stacks, Play and Akka, and Java since 1996. New services, upgrades and the refactoring that makes a codebase pleasant again.

  • Scala 3
  • Cats Effect
  • FS2
  • ZIO
  • http4s
  • tapir
  • Akka
  • Play
  • Java
  • Kotlin
04

Finance & XML

Electronic trading, risk and derivatives messaging for hedge funds and investment banks, plus serious XSLT and XQuery for finance and publishing.

  • FIX
  • QuickFIX/J
  • FpML
  • Derivatives
  • Risk
  • XSLT
  • XQuery
  • MarkLogic
Also
  • Python
  • Go
  • Rust
  • C
  • C++
  • Flutter / Dart
  • Kotlin
  • Postgres
  • MongoDB
  • SQL Server
  • AWS
  • Docker
  • Linux
Work

Recent engagements

Contracting through my own company, Felstar Ltd, since 2000. The CV has the full detail.

  1. 2024 – now

    H4 Group Tech Lead

    Document management for the construction industry (xmitted.com): a TypeScript stack on Cloudflare Workers, with RAG and LLM features built on Gemini and Claude.

    • TypeScript
    • React
    • Next.js
    • Bun
    • Elysia
    • Cloudflare Workers
    • Python
    • LanceDB
    • RAG
  2. 2023 – 2024

    Brevan Howard / Coremont Senior Scala Developer

    Front-office technology for a hedge fund: electronic trading, risk analytics and portfolio management. First hire on a new OMS team. Two engagements.

    • Scala
    • Cats Effect
    • FS2
    • FIX
    • QuickFIX/J
    • SQL Server
  3. 2021 – 2022

    ClearScore Senior Scala Developer

    Microservices behind credit scores, loans, credit cards and car finance.

    • Scala
    • Cats Effect
    • http4s
    • tapir
    • sttp
    • AWS
    • Postgres
  4. 2020 – 2021

    HMRC / Capgemini Senior Scala Developer

    Identity verification for Government Gateway, across 20+ microservices. Two engagements.

    • Scala
    • Play
    • Cats
    • MongoDB
    • Splunk
    • Grafana
  5. 2020

    Talenthouse Scala Developer

    Launch of talentclub.house, a GDPR- and COPPA-compliant site for young creatives.

    • Scala
    • Play
    • Akka
    • Slick
    • Postgres
  6. 2019

    Guardian News & Media Scala / Python Developer

    GDPR automation: subject-access and erasure requests fanned out to 20+ systems, and a Python codebase ported to Scala.

    • Scala
    • Play
    • Python
    • AWS Lambda
    • Athena
    • Vue
  7. 2016 – 2018

    Atos / HMRC Scala Developer

    Help to Save and Tax-Free Childcare: features, code review, major refactoring and the move to Play 2.5.

    • Scala
    • Play
    • ScalaTest
    • Mockito
    • GOV.UK
2006 – 2016 Show 12 earlier engagementsHide earlier engagements
  1. 2016

    On Track Retail Scala Developer

    Train ticketing.

    • Scala
    • Akka HTTP
    • Akka Streams
    • Slick
    • RabbitMQ
    • Docker
  2. 2015

    CAXIS Senior Scala Developer

    Proof of concept for an out-of-home advertising platform.

    • Scala
    • Vaadin
    • Slick
    • Leaflet
  3. 2014 – 2015

    Inkflash Scala Lead Developer

    A 3D bookstore built on Amazon data.

    • Scala
    • Scalatra
    • Vaadin
    • Neo4j
    • Akka
  4. 2014

    HSBC Java / XSLT Engineer

    EMIR delegated reporting for the Data Services Layer, via Oracle Consulting.

    • XSLT
    • Java
    • Saxon
    • FpML 5
    • Drools
  5. 2013 – 2014

    Barclays Corporate Scala Engineer

    Pingit for corporates, a strategic mobile payments platform.

    • Java
    • Scala
    • Spring MVC
    • Akka
    • Spray
    • Gatling
  6. 2013

    TSO XSLT Developer

    Unifying the UK government gazettes into The Gazette: an HTML5 UI in XSLT 2.0, plus an XForms engine.

    • XSLT 2.0
    • XQuery 3.0
    • MarkLogic
    • Java
    • RDF
  7. 2011 – 2012

    Standard Bank Integration Developer

    Real-time trade bus migration: changed the on-the-wire FpML for 60+ instruments without breaking anything downstream.

    • Java
    • XQuery
    • MarkLogic
    • FpML 4
    • Camel
  8. 2010

    HSBC Global Banking & Markets Java Developer

    Replaced manual and Excel-based procedures with an Ajax web UI.

    • Java
    • SQL Server
    • XSLT
    • jQuery
  9. 2010

    UniCredit eCommerce STP

    FX and FX options front office.

    • Java
    • Saxon
    • Murex
    • Kondor+
    • MQ
  10. 2009 – 2010

    JPMorgan Chase XQuery Developer

    XQuery transforms mapping derivative trade messages onto a new canonical format.

    • XQuery
    • XSLT
    • Saxon-EE
    • MarkLogic
    • FpML
  11. 2008

    Reuters / Thomson Reuters Java / XML Developer

    Imported multi-gigabyte Thomson data feeds into Oracle, before and after the merger.

    • Java
    • JAXB
    • Spring
    • Hibernate
    • Oracle
  12. 2006 – 2007

    Fitch Ratings / ValuSpread XSLT Developer

    Risk analytics platform for credit derivatives in the synthetic CDO market.

    • Java
    • XSLT 2.0
    • Saxon
    • Oracle
    • ActiveMQ
  1. 1986 – 2006

    The first twenty years

    Two decades before this list begins: C and C++, then Java from 1996. Ask me about it.

References

What people I’ve worked with say

Dino was my first hire on the new OMS team I had to build. He quickly learnt the architecture and data flows and even spotted issues with the specification for new work (the trader was wrong!). He helped on-board the new team members, contributed Scala code through the entire stack and could pair or work independently to deliver solutions. A great team member who I would enjoy working with again.

Jonathan GibbonsBrevan Howard, Coremont

Dino is hands down the strongest developer that I have met. Why is that? He does not rest on his laurels. Dino seeks and finds the truth.

Define a problem space, then solve that problem effectively. Thus his work reaches the sweet spot of being precisely what it needs to be. Hire a professional, cry once.

Dino offers his wisdom to those willing to grow. His advice is insurmountable to my growth as a programmer and individual.

His depth of expertise will benefit any project. I look forward to working with him in future.

William NarmontasJ.P. Morgan

Working at Caxis, Dino produced Scala code of a consistently high quality – a true talent. Generous with his knowledge, honest with his feedback. This wasn’t the first time I’ve worked with Dino, and I would gladly work with him again.

Matt StephensFingerpress

I was particularly impressed by Dino’s ability to handle and manage a high amount of work on such tight deadlines and has always delivered, but also the ability to juggle his workload and to support other members of his team, this showed that he made a dramatic difference in the teams productivity level. This seemed to come very naturally to him.

Without Dino and his Scala skills, there would have been so much we wouldn’t be able to deliver on time and up to such an amazing standard.

We kept Dino’s contract for almost 2 years till the end of the programme for his knowledge and wealth of experience. We tried to tempt him to join other projects, but Scala has spoiled him compared to other languages. I would certainly employ Dino again.

Michael AbadirAtos / HMRC

Dino is an exceptional developer with a forward looking and analytic mind. He went though all the requirements and identified the items that were incomplete or conflicting. His experience in Scala and XML is exceptionally valuable. The insights and value that Dino brought to the team were invaluable. It was a pleasure to work with Dino.

Aleksandr PanzinOrum.io

Dino is an avid developer, with a great understanding of Scala. He’s constantly looking to develop his skillset and challenge himself, despite his extensive experience. He’s a great contractor who delivers results and has an eye for detail. I’m looking forward to working with him again one day.

Reuben AdebamboExplore Group

I’ve had the pleasure of working with Dino for a few months and watching him grapple with the complexities of the software that my team curates has been something of a treat. I found that he was both effective and conscientious. His contribution boosted our team’s effectiveness immeasurably.

Andrew DwellyHMRC

I’ve worked with Dino before and he helped me get hired here. Dino was very helpful onboarding me as he’d worked extensively on the codebase. Dino is a top quality Scala Developer with a massive amount of real world I.T. experience and a strong knowledge of many technologies. He would be an asset to any team.

Charles FosterXML London

I worked with Dino on 2 separate Scala & Play Framework projects within Atos. Dino’s Scala knowledge really helped the team as a whole, providing specialist knowledge to us as well as suggesting and implementing code improvements to make our code more readable and efficient. Dino’s skills and ability to assist others with his knowledge of Scala and the Play Framework would be of great benefit for future employment and his colleagues.

Callum Taylor-StanleyAtos / HMRC

Dino worked on Scala project for us for 3 months. The client was based in a remote area of Scotland and so Dino had to travel up there initially and then undertake the work remotely from home. Dino was reliable and trustworthy producing high quality work 99% of which he was not onsite for and was working under his own volition.

Despite this the client also noted as well as the high quality of work produced Dino also integrated well into the team. Pleasure to work with, and I hope to work with Dino again very soon.

Giancarlo MoriniSurya Solutions

Dino was ready to take on tasks within a couple of days of joining the team. This was a marked contrast to several others that joined the project. … He is intelligent and has very good developer habits (config control, code style, tests etc).

Read the full referenceFull reference

Dino was one of several contractors to join a mixed skills development team on an initial contract of 3 months to support the closing stages of a project. I’m one of the team leads on the project, that means I do more management than programming.

Having followed the joining instructions and set up all the necessary software tools and dependencies with minimal fuss, Dino was ready to take on tasks within a couple of days of joining the team. This was a marked contrast to several others that joined the project.

The project consisted of a number of related web portals (over 200 unique pages) and the service layer to provide the data storage and complex business logic to support them. The portals were built using Scala on Play framework, the service layer (which Dino didn’t work on) was built in Java using a Redhat stack.

Dino initially took on the challenge of restructuring the web portals to reduce the complexity of the builds and to factor out some of the common/repeated code into more reusable modules. This was carried out as a series of Stories over a couple of 2 week Sprints and significantly improved the state of the code base.

Some of his other tasks included:

  • changing the API’s between the portals and the service layer to resolve issues with stored data and user friendly presentation of previous user selections
  • updating HTML/CSS for a better user experience on mobile devices
  • numerous minor bug fixes and miscellaneous tasks

The final piece of work Dino carried out was to upgrade all the portals from Play 2.4 to Play 2.5. This was a significant task due to fundamental changes and deprecation’s in the Play framework. Again this was delivered with no fuss, just a few jokes along the way.

As it turned out the expected loss of 4 staff did not happen and so Dino was no longer required. So, is Dino the perfect contractor, no – but then who is? He is intelligent and has very good developer habits (config control, code style, tests etc). Dino is able to research techniques and tools that he has not used before and then apply them effectively with the added bonus of his years of experience. On the other hand, working remotely on large tasks, he can go quiet for long periods – it would be nice to get progress updates a little more frequently.

Working with Dino has been easy. He has taught us a few tricks and I think all parties have benefited from the experience. Ultimately, if I was in need of extra staff on another project I wouldn’t hesitate to request Dino.

Ian WelshAtos / HMRC
Projects

Recent builds

Mostly from the last couple of years. Plenty more on GitHub, Hugging Face and in my gists.

AI & machine learning

cctv_llm_browser

Finds people in CCTV footage with OpenCV, has an LLM describe what they’re doing, and builds browsable HTML viewers.

PythonOpenCVVision LLM

fastmcp-space

An MCP server built with FastMCP and deployed to Hugging Face Spaces without Gradio.

PythonMCPSpace

gmail_spam_handler

Watches a Gmail inbox, classifies new mail with a Hugging Face transformer and moves the spam out of the way.

PythonTransformers

langChainDemo

A collection of small LangChain applications: retrieval with ChromaDB, Hugging Face and OpenAI models, Flask front ends.

PythonLangChainRAG
Full stack & web

bun-fullstack-elysia

A full-stack starter on Bun 1.3: Elysia API and React, bundled by Bun itself with no Vite or Webpack.

TypeScript★ 8

vite-node-react-elysia

End-to-end type safety from API to UI with Elysia and Eden Treaty on Node, React via Vite.

TypeScript

relic_swarm

A 2D horde-survival roguelite with weapon fusions and meta-progression, in React and TypeScript.

TypeScriptReactPlay it

Also lately: games in Go with Ebitengine and Cogent Core, a Gin web app, Kotlin with Jetpack Compose, Rust in an 11 MB Docker image, Pygame running in WebAssembly, and VHDL on an FPGA.

Scala & functional programming

scalajs-vue

Scala.js bindings for Vue.js, with an example application.

Scala★ 112

zio-restful-webservice

A ZIO 2 REST service covering zio-http, zio-json, Quill, streams, caching, actors and OpenAI.

Scala★ 59

xqs

XQuery for Scala.

Scala★ 36

fs2-examples

FS2 and ZIO streaming: file IO, moving averages, queues, an echo server and a REPL.

Scala 3★ 7
Writing
Contact

Let’s talk.

Contracts through Felstar Ltd: outside IR35 and fully remote. Scala, TypeScript, Python, AI or something else entirely; email is the quickest way to reach me.