Jon is available for hire
Hire JonJon Breen
Verified Expert in Engineering
Full-stack Developer
London, United Kingdom
Toptal member since March 19, 2025
Bio
Jon is a full-stack developer who has worked for clients such as BBC Worldwide, Clearbank, Bank of Montreal, and AKQA. He specializes in C# and Angular and abides by best practices such as test-driven development (TDD), SOLID principles, and DevOps. Jon works with multiple back-end services, such as Azure, AWS, Service Bus, SQL Server, and Redis. He would make an excellent asset to any team.
Portfolio
Sharp Europe
C#, Windows Presentation Foundation (WPF), Azure, Azure Service Bus...
VavaCars
C#, Azure DevOps, .NET
The People's Pension
C#, .NET
Experience
- SQL - 20 years
- C# - 18 years
- Software Engineering - 14 years
- Azure DevOps - 8 years
- Azure - 8 years
- Azure Service Bus - 7 years
- Angular - 2 years
- Cloudflare - 2 years
Availability
Full-time
Preferred Environment
Azure, C#, Angular, Cloudflare, .NET
The most amazing...
...thing I've developed was the UEFA Champions League in-game video service for Vodafone customers in 2005.
Work Experience
Senior Software Engineer
2023 - 2023
Sharp Europe
- Refreshed Windows Presentation Foundation (WPF) application to use Azure cloud-based service bus flow to enable office printer integration and installation via Microsoft Store.
- Integrated it with enterprise licensing systems to control tenants, users, and devices for cloud-based printing systems.
- Introduced SQL Server deployments and liaised with DevOps to enhance delivery and configuration.
Technologies: C#, Windows Presentation Foundation (WPF), Azure, Azure Service Bus, Redis Cache, .NET
Senior Software Engineer
2022 - 2022
VavaCars
- Constructed and maintained multiple microservices, releasing features nearly daily to deliver new user features.
- Influenced the development culture to prioritize team-based code reviews to improve code quality and service awareness across geographically distributed teams.
- Worked within a geographically distributed team and covered for teammates due to instability in their country.
Technologies: C#, Azure DevOps, .NET
Senior Software Engineer
2021 - 2021
The People's Pension
- Collaborated with junior developers to train them on how to work with a legacy client-facing system to enable them to add new functionality in a testable manner.
- Refactored application code that did not adhere to engineering principles to allow for agile development of new features.
- Liaised with stakeholders to find a balance between refactoring to aid future development and abiding by time constraints to deliver new features and bug fixes.
Technologies: C#, .NET
Senior Software Engineer
2020 - 2021
Cera Care
- Provided short-term Christmas cover for the Cera Care app back end, incorporating minor enhancements to the shared codebase and integration testing framework.
- Improved logging to aid the developer in observing the system.
- Assisted other developers in onboarding and independently commencing development on unfamiliar systems.
Technologies: C#, .NET
Senior Software Engineer
2020 - 2020
Infinite Software
- Managed production infrastructure and systems independently, overseeing around a dozen services utilizing Amazon EC2, AWS Lambda, Kubernetes, manually provisioned resources, and a distinct secure development environment from production.
- Produced new products using AWS CloudFormation to introduce the secure development-model hosting environment to production and automated the deployment pipeline from Azure DevOps.
- Developed AWS Serverless solutions with .NET Core 3.1, Amazon SQS, Amazon SNS, and AWS S3, incorporating AWS features like API Gateways, Lambda authorizers, and X-Ray for observability.
Technologies: C#, AWS Lambda, AWS CloudFormation, AWS Serverless Application Model (SAM), Kubernetes, .NET
Senior Software Engineer
2019 - 2019
BookingTek
- Maintained a restaurant platform as a platform as a service (PaaS) comprising OAuth2, Web API, and SignalR C# components.
- Employed Azure DevOps to manage code hosting to build and ship products in a Kanban style, deploying it to AWS EC2 instances.
- Worked in an environment experiencing high staff turnover to deliver new features and bug fixes.
Technologies: C#, Kubernetes, OAuth 2, .NET
Senior Software Engineer
2018 - 2019
BMO Bank of Montreal
- Maintained a regulatory reporting system by developing new trade-data ingestion mechanisms and adding features to facilitate automated testing.
- Validated the numerical accuracy of calculations featured in reports.
- Tested interdependent SQL components within the system due to its highly regulated environment where feasible.
Technologies: C#, SQL, T-SQL (Transact-SQL), .NET
Senior Software Engineer
2017 - 2018
ClearBank
- Worked in a small team to meet regulatory banking needs for client accounts and supporting infrastructure systems. Employed SOLID/TDD principles and did code reviews in a robust development environment to deliver high-quality, tested code.
- Refactored a large Web Forms C# monolithic system into C# microservices hosted on Azure Service Fabric. Enhanced code quality and test coverage and took charge of critical services, improving their internal architecture.
- Oversaw release pipelines for key services in a dynamic environment using Azure DevOps builds and releases. Led product launches, collaborated with developers to comply with regulatory timelines, and ensured timely delivery of new functionalities.
- Leveraged expertise in architecting scalable systems for end users through CQRS, microservice architectures, SOLID, and TDD in a collaborative, agile setting. Organized interdependent .NET C# services using NuGet releases and SemVer versioning.
Technologies: C#, Microservices, Azure, Azure DevOps, .NET
Senior Software Engineer
2017 - 2017
Spark44
- Employed .NET Core to develop a chatbot infrastructure from the ground up, applying SOLID principles and TDD to deliver high-quality solutions in the face of evolving requirements.
- Constructed complete user tracking and market localization features. Leveraged Entity Framework (EF) Core and .NET Core 1.1 to expedite product launch within a month, ensuring comprehensive test coverage.
- Implemented a Kanban process to capture business requirements from stakeholders and facilitate an agile process in a non-technical work environment.
Technologies: C#, Facebook API, Facebook SDK, Chatbots, .NET
Developer
2010 - 2012
BBC Worldwide
- Contributed as a back-end developer on RadioTimes.com within a Kanban team, operating in a TDD environment across various technologies such as model–view–controller (MVC), Sitefinity, and Redis. Delivered a new iteration of the website successfully.
- Employed test-driven and continuous integration practices for client-side JavaScript development on the RadioTimes Ajax library and BBC Worldwide single-sign-on (SSO). Utilized TeamCity, Chutzpah, and QUnit for the project.
- Managed TopGear.com and oversaw the migration of hosting infrastructure to a new environment for user acceptance testing (UAT) and live, addressing ongoing concerns like safeguarding against XSS attacks.
Technologies: C#, ASP.NET MVC, JavaScript, .NET
Developer
2009 - 2010
AKQA
- Maintained and developed the back-end architecture for Sky's online ordering site, integrating dual VAT rates to update all pricing on the website in preparation for the January 1st VAT increase.
- Assisted in the ongoing migration to an Akamai edge-cached site, ensuring site functionality met expectations. Developed custom diagnostic tools to aid in adjustments when clients modify their Akamai services.
- Introduced new features to enhance the product, delivering an improved user experience to drive the adoption of Sky products like Satellite, Broadband, and Telephony.
Technologies: C#, ASP.NET, .NET
Experience
Cult Podcasts
https://cultpodcasts.com/Inspired by research by Dr Janja Lalich, Cult Podcasts is an online database of testimonies in podcast form of survivors of coercive control in group environments. The system includes bots to index and categorize content from syndicated feeds and publishing bots to promote content on multiple platforms. It has been well-received by a number of academic experts.
Education
1992 - 1997
Bachelor of Science Degree (Honors) in Computer Science
De Montfort University - Leicester, UK
Skills
Libraries/APIs
Facebook API, Facebook SDK
Tools
AWS CloudFormation
Languages
C#, SQL, T-SQL (Transact-SQL), TypeScript, JavaScript
Frameworks
.NET, Angular, Windows Presentation Foundation (WPF), AWS Serverless Application Model (SAM), OAuth 2, ASP.NET, ASP.NET MVC
Paradigms
Azure DevOps, Microservices
Platforms
Azure, Azure Functions, AWS Lambda, Kubernetes
Storage
Redis Cache
Other
Software Engineering, Azure Durable Functions, Cloudflare, Azure Service Bus, Chatbots
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