Full Stack Engineer

Founding Full-Stack Engineer – Early Stage Fintech Start-up (Contract)

A mission-driven fintech start-up is looking for a Full-Stack Engineer to join as the first engineering hire and help build a new mobile banking product focused on improving financial wellbeing.
You’ll work closely with the founding team to design and build core platform features, including integrations with Banking-as-a-Service providers, payment controls, and user financial insights. This is a rare opportunity to join at the ground floor and shape the engineering function as the company grows.
The platform includes a React Native mobile application, a GraphQL-based API, and cloud infrastructure on AWS.

What you’ll be doing

• Building and extending a React Native mobile application
• Developing backend services and APIs using Node.js and GraphQL
• Integrating with Banking-as-a-Service and third-party financial APIs
• Designing data models and handling financial transaction data
• Working within a cloud-based infrastructure on AWS
• Contributing to architecture decisions and helping shape the engineering foundations of the platform

Key skills

• Strong experience with TypeScript / JavaScript
• Experience building React Native mobile applications
• Backend development using Node.js, APIs and GraphQL
• Experience integrating with third-party APIs
• Comfortable working with AWS cloud environments
• Good understanding of security and sensitive data handling

Nice to have

• Fintech, payments or open banking experience
• Experience working with Banking-as-a-Service or financial APIs
• Familiarity with infrastructure as code (e.g. Terraform)

Contract Structure, Budget & Future Opportunity
This role is offered on a flexible contract basis to suit the right engineer.
The project has a maximum budget of £10,000–£10,200 for the initial 3-month phase. How that budget is used is flexible and can be structured in different ways, including:

• Full-time engagement across the 3 months (or less if feasible)
• Part-time contribution alongside other work
• Hourly or milestone-based delivery

The focus is on delivery and outcomes rather than rigid time commitments. If the scope can be completed sooner or in fewer hours, the effective rate can increase accordingly within the project budget.
The contract is extendable, with the potential to transition into a longer-term or permanent role as the company grows. The business currently has early-stage backing from a well-known UK high street bank, with a second funding round planned to support expansion.
For the right person, this represents an opportunity to join early and grow into a Principal Engineer / CTO-level role as the product and company scale.