Senior Full-Stack Software Engineer

Marius Olariu

London, UK · Settled status, no sponsorship needed

I specialise in backend software development with Java, Spring and AWS; I am also familiar with frontend development using TypeScript, React and Next.js. At Strategic Imperatives (November 2024 – present), most of my work has been on Elevate, a billing platform that processes around £100M a month for UK telecom resellers. Before that I worked in the Checkout team at Vodafone, where through constant effort and dedication I earned the Vodafone Top Talent award. I have used AI in my daily engineering practice since 2023 and have given talks on it at Vodafone and at Strategic Imperatives, where my talks and being the main contributor to the internal knowledge-sharing channel earned me the AI Champion award. I keep learning and sharing the latest developments.

Top skills

Recent highlight

At Strategic Imperatives I led the billing team's adoption of AI-assisted development: the team's throughput at least doubled with no production incident. More at Strategic Imperatives section.

Experience

Senior Full-Stack Software Engineer

Strategic Imperatives (opens in a new tab) · Woking, hybrid · Nov 2024 – Present

Cloud billing and fibre platforms for UK telecoms providers

Chose to return to hands-on engineering after leading a team at Vodafone, and have spent most of my time here on the Elevate billing team, working across the codebase: payments, invoicing, the rental engine, the frontend and more. Elevate processes roughly £100M of monthly revenue and handles invoices with over a million call records.
Contributed a good part of the architecture and early direction of View my Bill, a new brownfield project that lets our customers' own customers download their bills and see their consumption. It pairs a backend-for-frontend over our REST services with a Next.js app as the frontend.
Took part in the move away from monolithic systems towards Spring Boot microservices on Java 17 and above.
Led the team's adoption of AI-assisted development: a shared agent configuration, custom verification skills and a domain-knowledge index across about 33 repositories. Throughput at least doubled with no production incident attributed to it. Two internal talks on the subject, a cross-team upskilling channel I am the main contributor to, and the AI Champion award followed.
Built the shell tools an Elevate developer uses daily: launch the whole Java stack in one command, pull and initialise a client database from a production backup, and drive the test deployment server over a single shared SSH connection instead of a new login per command.
Moved in 2026 to the Fibre team, which had more demand than engineers, at my manager's request so the same practices could take root there. The stack is TypeScript, Next.js and AWS Serverless, which builds on the React and Node work from earlier in my career.

Backend Software Engineer, then Software Team Lead

VodafoneThree (opens in a new tab) · London, hybrid · Feb 2023 – Jul 2024

UK mobile and broadband network operator

Software Team Lead, Apr 2024 – Jul 2024
Backend Software Engineer, Feb 2023 – Apr 2024

Built and maintained the Java and Spring Boot microservices behind Vodafone's online checkout, the last step of buying a plan or a phone: collecting the customer's details, verifying their identity, taking payment and handing the complete order to the fulfilment systems.
Improved how the team used Git and pull requests: small, well-titled commits, formatting changes kept out of functional ones, and pull requests that read as a story a reviewer can follow.
Gave a talk on ten use cases for AI in our work, the first of a series I have kept up since.
Recognised as Top Talent, one of four from about 80 engineers, while still a mid-level developer, and promoted to lead a team of seven: five developers, a tester and a scrum master.
After a short spell in a developer and management role, I realised that management is not the branch of software engineering I want to pursue long term. I returned to an individual-contributor developer role and moved to Strategic Imperatives.

Full-Stack Software Engineer

IQVIA (opens in a new tab) · London, hybrid · Feb 2022 – Oct 2022

Clinical research and health-data company

Worked across the stack in Groovy, Grails and JavaScript on an eSource and Phase I clinical-trial automation system used by the largest pharmaceutical companies, working with biomedical engineers, product owners and other disciplines to derive requirements and find the right software solution for our customers.
Often provided third-line support for UK customers single-handedly in the UK morning, as most of the team was US-based and online from about 4pm. Unblocking large clinical sites, where studies with tens of patients were under way and a quick fix mattered, was the most rewarding part of the role.
A short stint: the project was a legacy but successful one on dated technologies, with little room to grow.

Software Engineer

Diffblue (opens in a new tab) · Oxford, hybrid · Aug 2020 – Feb 2022

AI tool that writes unit tests for Java code

Developed software in Java for Diffblue Cover, a tool that generates unit tests using reinforcement learning. Set up and maintained the online environment used to trial the product.
My tech lead, who recognised my potential, had me run some of the stand-ups and retrospectives. I made the most of colleagues from computer-science academia and spent a lot of time, online and offline, learning from them.
Left when my partner and I decided to move to London; the weekly commute to Oxford proved costly.

Junior Full-Stack Software Engineer

New Verve Consulting (opens in a new tab) · Glasgow, on site, full-time · Aug 2019 – Aug 2020

Atlassian partner consultancy (Jira and Confluence)

Designed and built a Jira Cloud add-on, a lightweight CRM, in React and Node on AWS, while finishing my MSc dissertation.
Mentored a technical consultant into a developer role.
Left when my partner secured a job in Oxford and we decided to move there.

Junior Software Engineer

SSI Schäfer (opens in a new tab) · Timișoara, Romania, on site, part-time · Sep 2017 – Aug 2018

Warehouse automation and storage systems

Contributed to the development of the Java control software for a vertical lift warehouse module, in parallel with the final year of my BSc.
Left to pursue a master's degree in Mobile and Web Development in Scotland.

Technical skills

Backend: Java 17+, Spring Boot, REST APIs, Microservices, Event-driven architecture
Frontend: TypeScript, React, Next.js, JavaScript
Cloud and infrastructure: AWS
Data: MySQL, SQL, Liquibase
Testing: JUnit, Jest, Karate, Test-driven development

Soft skills

Team player Main contributor to the cross-team upskilling channel at Strategic Imperatives.
Knowledge sharer Talks on developer productivity at Diffblue, AI use cases at Vodafone and AI-assisted development at Strategic Imperatives, which earned me the AI Champion award.
Personable Get on well with colleagues; trusted to mentor and run ceremonies from early on.
Mentor Coached a technical consultant into a developer role at New Verve Consulting; taught coding to 7 to 18 year olds at YMCA Paisley.
Self-directed learner A lifelong learner: the Oxford Saïd Senior Leadership Executive Programme (2024), Erasmus semesters in Sweden and the Netherlands, and a master's in Scotland.
Takes ownership Built the team's environment and deployment tooling at Strategic Imperatives unprompted; I share my automations with the team.

Education

Senior Leadership Executive Programme, University of Oxford, Saïd Business School (Nov 2024)
MSc Mobile and Web Development, University of the West of Scotland, distinction (2019)
BSc Computer and Software Engineering, Politehnica University Timișoara, distinction (2018)
Software Engineering, Erasmus exchange semesters, Linköping University and Radboud University (2017)

Outside work: Coding Mentor at YMCA Paisley, Sep 2018 – Aug 2019. Taught coding to young people aged 7 to 18 in Paisley.