Senior Software Engineer – Financial Systems, Data Migration & AI-Assisted Development

Location: Mandatory on-site attendance in Cheltenham for the first month.
Reporting to: Chief Technology Officer

About the company

An established, growing software business specialising in financial account management is seeking a highly capable Software Engineer to support product development and improve client implementation processes.

Our platform supports complex business workflows, financial calculations, customer data management and integrations. This position offers substantial technical responsibility across application development, data migration, AWS infrastructure and AI-assisted engineering.

Applications are welcomed from experienced senior engineers and strong mid-level candidates who can demonstrate the required technical capability and readiness to take ownership.

Location requirement

The successful candidate must work on-site with the team in Cheltenham throughout their first month.

This requirement is non-negotiable. Please do not apply if you are unable or unwilling to commit to this arrangement.

Role overview

Reporting to the CTO, you will contribute to the development and maintenance of the platform, with particular emphasis on financial processing, complex data migrations and reusable implementation tooling.

Confident, regular use of AI-assisted development tools is essential. We are looking for an engineer who already incorporates AI into their daily workflow, can demonstrate its practical benefits and takes responsibility for the accuracy and quality of the resulting work. Let us know how many terminals you typically work with in your application to us.

You will work in a fast-paced, evolving Agile development environment where requirements and priorities can change. You should be motivated by challenging problems and comfortable progressing work when information is incomplete - identifying uncertainties, asking focused questions and developing practical solutions.

This role requires confidence working with ambiguity and changing priorities. Please do not apply if you require a predictable, unchanging scope to work effectively.

The role includes approximately 10% client-facing activity, primarily to clarify technical requirements and resolve data-related queries.

Key responsibilities

• Develop and maintain enterprise applications using PHP, React, Node.js and MySQL.
• Deliver complex data migrations, including source-data analysis, mapping, transformation scripts, validation, reconciliation and production cutover.
• Develop reusable migration tools and processes that reduce manual effort, identify exceptions and preserve data integrity.
• Develop and maintain financial processing functionality, including balances, interest, fees, payment allocation, adjustments and reconciliation.
• Analyse complex technical and financial requirements and translate them into clear, practical software solutions.
• Design and maintain APIs, integrations and reliable background processing.
• Investigate complex defects, optimise database performance and improve existing code safely.
• Support AWS infrastructure, CI/CD pipelines, monitoring, deployment and recovery procedures, coordinating with external infrastructure providers as required.
• Contribute actively to Agile planning, estimation, refinement, reviews and retrospectives, delivering work in manageable, testable increments.
• Maintain engineering standards through automated testing, constructive code reviews, secure development and technical documentation.
• Use AI coding assistants and development agents confidently for development, debugging, testing, refactoring and migration work.
• Identify opportunities to improve development and implementation through AI and automation, with appropriate validation and confidentiality controls.
• Take ownership of work through development, testing, deployment and verification.

Essential qualifications and experience

• A strong degree in Computer Science.
• Demonstrable experience developing and supporting enterprise or business-critical software.
• Strong PHP and backend development skills, with experience using React and Node.js.
• Advanced MySQL and SQL skills, including relational data modelling, transaction handling, indexing and query optimisation.
• Substantial hands-on experience delivering complex data migrations, including mapping and transformation scripts, data validation and financial reconciliation.
• Experience developing or maintaining financial calculation engines or transaction-processing systems, with an understanding of numerical precision, rounding, auditability and data integrity.
• Confidence working with mathematics and linear algebra to solve software problems, with the ability to select appropriate techniques and verify results.
• Practical experience with AWS and DevOps, including CI/CD, production troubleshooting, monitoring and secure configuration.
• Experience working within an Agile software development team, including iterative delivery, backlog refinement, estimation and adapting to changing requirements.
• Experience with automated testing, version control, pull-request reviews and secure development practices.
• Confident, regular use of AI-assisted development tools, such as Claude Code, GitHub Copilot, Cursor, OpenAI Codex or comparable tools.
• The ability to direct AI-assisted work effectively, review generated changes critically and validate outputs through testing and other appropriate checks.
• Sound judgement regarding confidentiality, security and accuracy with sensitive data and financial software.
• The ability to analyse complex technical requirements and develop clear, practical solutions.
• Clear written and verbal communication skills, including the ability to explain technical issues to non-technical stakeholders.

Professional attributes

• Strong analytical reasoning, intellectual curiosity and the ability to understand unfamiliar systems quickly.
• Enthusiasm for solving challenging problems in a fast-paced, continually evolving environment.
• Confidence working with uncertainty, combined with the judgement to clarify assumptions and escalate material risks.
• A collaborative, low-ego approach, with openness to feedback and a willingness to reconsider decisions when evidence supports a better solution.
• A commitment to producing high-quality, maintainable software.
• Personal accountability for delivery, quality and resolving issues.
• A practical approach to balancing technical quality, business priorities and delivery timelines.
• A willingness to share knowledge, support colleagues and contribute constructively to team decisions.

Desirable experience

• Experience in banking, lending, loan servicing, payments or accounting software.
• Large-scale migrations involving legacy systems, inconsistent source data or incomplete documentation.
• Development of configurable mapping tools, reusable transformation libraries and automated reconciliation reports.
• Design of integrations that handle retries, duplicate messages and partial failures reliably.
• Infrastructure as code, recovery testing and performance monitoring.
• Modernisation of established software while maintaining operational continuity.
• Development of AI-enabled product features or internal implementation tools.

Application process

Please submit your CV by clicking on Apply now and a brief supporting statement covering:

• A complex technical problem you personally resolved, including how you handled unclear or changing requirements.
• A data migration you delivered and how you verified its completeness and accuracy.
• Your experience with financial systems, AWS and Agile development.
• A substantive task you completed using AI-assisted development tools, including how you directed the work, validated the output and addressed any errors or limitations.

Your application must confirm your availability to work on-site in Cheltenham throughout the first month.