About the company

You will be joining the payment solution OnPay as part of a team dedicated to growing our presence across Europe. Online payments are becoming more prevalent every day and our mission is to support our growing merchants by remaining at the forefront of product offerings and reliability. This is where you come in.

As a team, we collaborate on the entire software development lifecycle where security and compliance are fundamental to OnPay's success and require high attention to detail to ensure that the millions of transactions we process monthly remain secure and seamless.

About the position

We are seeking a Lead Developer to take full ownership of the frontend on the OnPay platform. The ideal candidate has a strong background in modern frontend engineering, a proven track record of leading frontend work in a product environment, and a genuine appetite for working AI-native – using agentic tooling (Claude Code, Devin and similar) as a daily force multiplier rather than a side experiment.

Reporting to the Software Director, the Lead Developer (Frontend) is part of the OnPay core team alongside the Architect and Tech Lead, with day-to-day collaboration across the team and clear delegation to UI/UX, QA and plugin/frontend enabling functions. You will own the frontend across the full chain: contributing to product scoping and prototyping upstream, driving technical execution and architecture for the frontend, and staying engaged downstream on quality, UX feedback and production behaviour.

Key Responsibilities

Own the frontend end-to-end

Take full responsibility for the OnPay frontend – architecture, code quality, performance, accessibility and frontend implementation of the merchant-facing product.

Upstream product partnership

Work closely with the Product Manager on planning, scoping and AI-assisted non-functional prototypes. Bring frontend constraints and opportunities into product decisions early, not after the fact.

AI-native delivery

Lead frontend development in an agentic model – orchestrating and reviewing AI-generated code, pair-programming with agents, and continuously raising the bar on how we use AI tooling across planning, development, code review and test generation.

Technical direction for frontend

Set and evolve the frontend technical direction in close cooperation with the Architect and Tech Lead. Establish standards, guardrails and patterns that allow the small core team to ship fast and iterate without compromising the platform.

Code review and quality assurance

Drive AI-assisted code review with human approval. Ensure coding standards are met and PCI DSS Level 1 requirements are upheld – treating compliance as a strength, not an obstacle.

Domain ownership

Build and maintain deep product and domain knowledge of the OnPay platform and the payments space, so that you can make well-grounded technical and product trade-offs and reduce the bus factor on the frontend.

Collaboration across the chain

Delegate and collaborate with UI/UX, QA, plugins/frontend and 2nd level support. Help define what good looks like at the boundaries between core team and enabling functions.

Raise the frontend bar

Set the standard for frontend craft and AI-native ways of working – through code review, pairing, and shared practices. Act as a frontend reference point for other team.blue teams adopting the same model.

Qualifications

• Domain experience in payments, fintech, e-commerce or another regulated/transactional domain – able to ramp up quickly on the OnPay product and the payments ecosystem.

• A seasoned background with 5-7+ years in frontend development, including a proven track record of leading frontend work in a product lead team.

• Strong, hands-on experience with modern frontend stacks (e.g. TypeScript, React/Vue or equivalent), including state management, performance, accessibility and frontend testing.

• Demonstrated experience working AI-native: daily use of agentic coding tools (e.g. Claude Code, Devin, Copilot or similar) on real production work, with a clear point of view on where AI helps, where it doesn't, and how to keep humans in the loop on review and approval.

• Solid understanding of frontend architecture, design systems, API integration and how the frontend fits into a wider platform – able to think beyond "the screen" and into the full delivery chain.

• Strong understanding of product thinking – comfortable engaging with product managers, prototypes and merchant signals, not only with tickets and specs.

• Exceptional decision-making skills, effective communication, and a strategic outlook on frontend development.

• Skilled in profiling, debugging and using code quality tools to maintain a high bar, with the ability to identify and address performance bottlenecks.

• Ability to thrive in a fast-paced and dynamic environment, with a proactive and entrepreneurial mindset.

• Proficiency in English; Danish is a plus.

• Comfortable with hybrid work, with regular in-person collaboration days alongside the core team.

In your advantage

• PCI DSS experience or other compliance/audit-heavy frontend work.

• Experience leading a frontend function through a transformation (tooling, process, team shape) – not just maintaining the status quo.

• Experience contributing to or shaping a design system used across multiple products or brands.

• Bachelor or master degree in Computer Science, Engineering or related field.

• Must hold a valid work permit for Belgium, the Netherlands, Denmark, the UK, or Germany.