Staff Engineer

Flagstone Group

Greater London

On-site

GBP 90,000 - 120,000

Full time

14 days+

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Benefits offered by this job

Hybrid work London

Bonus scheme

Benefits budget

Salary sacrifice

Around the World work from anywhere

Wellbeing support

Personal development budget

Private health care

Medical cash plan

Life insurance & income protection

Pension matching

25 days holiday

Parental leave

Job summary

Flagstone is seeking a Staff Engineer specializing in front-end and mobile to set technical strategy and drive high-quality React and React Native systems across multiple squads.

You will mentor engineers, shape architecture, and lead design-system evolution while partnering with product and design to deliver business value. This hybrid role is based in London and offers a range of benefits and growth opportunities.

Qualifications

Staff Engineer (or equivalent) with frontend and mobile focus.
Deep expertise in React and React Native with TypeScript.
Owning and evolving a design system used across web and mobile.
Strong system architecture skills with SOLID, TDD, DDD.
Experience with Azure development, CI/CD, and observability.
Threat modelling and security hardening for frontend products (OWASP).
Originating and shepherding cross-team RFCs and initiatives.
Coaching, mentoring, and leadership to multiply impact.
Excellent stakeholder management and communication; external representation.

Responsibilities

Lead frontend and mobile strategy across a tribe of 3–5 squads.
Partner with squads, Engineering Leads, and Product to align tech with business goals.
Mentor engineers and grow system design skills; contribute hands-on to key projects.
Own cross‑platform architecture decisions for web and mobile (React/React Native/TypeScript).
Drive evolution of shared design system across web and mobile for consistency and velocity.
Lead CoP activities to spread frontend engineering practices.
Identify emerging technologies and build roadmaps for adoption.
Drive observability, zero-downtime deployments, and robust monitoring.
Own security practices and code reviews to maintain high standards.
Represent Flagstone externally via talks and community engagement.

Skills

React & React Native

Design system ownership

System architecture

Security & OWASP

Azure & CI/CD

Coaching & leadership

Agile / Scrum

Cross-team RFCs

Frontend & mobile strategy

Stakeholder management

Tools

Azure DevOps

Job description

What is Flagstone?

Flagstone is many things. An online savings platform, reinventing how individuals, businesses, and charities manage, protect, and grow their cash. A diverse group of people, bound by a collaborative spirit, and shared purpose. And lastly, a thriving, profitable business – where smart people do their best work.

Each definition shares a common thread: our unique culture. It’s our pride and joy. And our competitive advantage.

A feel for our culture:

To revolutionise the savings market, we need to be at our best. But high performance takes more than talent – it takes a culture of kindness, respect, and growth.

That’s why we’re building a diverse, inclusive community, where your voice is heard and valued. Where, with close support and room to develop, you can surpass even your own expectations. And be rewarded for it.

We may not change the world, but we can change the world of financial technology. And all it takes is a winning mix of drive, talent, and empathy. Our culture celebrates all three.

But enough about us. Let’s talk about you.

Does this sound like you?

You’re a passionate and experienced Staff Engineer specialising in front-end and mobile, who's excited to forge a new way to save! You set the technical bar for React and React Native across a tribe of squads, drive cross-team initiatives, and act as a force multiplier - coaching engineers, shaping architecture, and representing Flagstone in the wider engineering community.

What you’ll do:

The Staff Engineer will take a leading role in driving front-end and mobile technical strategy across a tribe of 3–5 squads, ensuring the delivery of high-quality systems that meet our business objectives. You'll partner with squads, Engineering Team Leads, and Product to identify how technology can solve business challenges and take a long-term view on company value.

You'll also play a crucial role in mentoring and coaching engineers, helping them grow their system design skills and ship robust, scalable solutions. As a technical leader, you'll provide strategic guidance while also contributing hands‑on to key projects. This will focus on:

Technical Strategy: Set the front‑end and mobile technical vision in collaboration with Engineering Team Leads, aligning with wider business objectives.
Cross‑Squad Leadership: Originate and lead horizontal engineering initiatives across the tribe; author and shepherd RFCs from proposal to adoption.
Solution Delivery: Contribute directly to building and maintaining high-quality React and React Native systems while supporting and unblocking other engineers.
Architecture & Design: Own cross‑platform architecture decisions for web and mobile (React, React Native, TypeScript), ensuring scalable, reliable, and efficient design with a forward‑looking approach.
Design Systems: Lead the evolution of our shared design system across web and mobile, driving consistency, accessibility, and developer velocity across squads.
Mentorship & Multiplier Impact: Coach engineers in system design, coding standards, and testing; start initiatives that others complete; delegate to protect bandwidth for the highest‑leverage work.
Communities of Practice: Drive adoption of front‑end and mobile engineering practices through CoP leadership and engagement across the tribe.
Horizon Scanning: Identify emerging front‑end and mobile technologies, build proof‑of‑concepts, and create roadmaps for adoption.
Operational Excellence: Champion the "you build it, you run it" philosophy - driving pipeline observability, zero‑downtime deployments, robust monitoring, and alerting for front‑end applications.
Resilience & Performance: Design solution‑wide UI resilience (graceful degradation, back‑pressure, retry strategies) and own performance standards across web and mobile.
Quality, Security & Compliance: Own threat modelling and security hardening for tribe front‑end products; maintain high standards through code review, secure coding practices, and risk management.
External Representation: Represent Flagstone externally through conference talks, podcasts, or published content; help attract senior engineering talent through your network and reputation.
Collaboration: Work closely with Product Managers, designers, stakeholders, and cross‑functional teams to align technical decisions with business needs.

What you’ll bring:

Proven experience in a Staff Engineer (or equivalent) role with a front‑end and mobile focus.
Deep expertise in React and React Native with TypeScript, including cross‑platform architecture.
Track record of owning and evolving a design system used across web and mobile applications.
Strong system architecture and design skills, with thorough understanding of SOLID principles, TDD, DDD, and software design patterns.
Experience designing for resilience and performance at scale (graceful degradation, zero‑downtime deployments, observability, performance budgets).
Experience with Azure development and cloud‑based infrastructure, including CI/CD and pipeline observability.
Experience owning threat modelling and security hardening for front‑end products; strong grasp of OWASP and secure coding practices.
Track record of originating and shepherding cross‑team initiatives or RFCs to adoption.
Excellent coaching, mentoring, and leadership skills - with evidence of being a force multiplier, not just a strong individual contributor.
Strong problem‑solving abilities and strategic thinking.
Effective stakeholder management and influencing skills.
Comfortable representing Flagstone externally (talks, writing, community engagement) - or keen to start.
Agile and Scrum practices experience.

How we reward you:

At Flagstone, the benefits extend beyond false gifts like “fruit and snacks”. Instead, we invest in your health, wealth, and professional development. Here’s a selection of our benefits:

Hybrid working - Spend at least 1 day a week with your team in our collaborative London office
Competitive bonus scheme - designed to reward and recognise high performance
Flexible benefits budget - a pot to fund meaningful benefits for you, whether it's hormone or fertility testing, cancer screening, neuro‑diversity coaching or something that matters for you.
A range of salary sacrifice options to help you make tax efficient savings on electric cars, nursery schemes, home and tech goods.
Around the World scheme - 3 months work from anywhere scheme
Mental wellbeing support – Access therapy and mental health sessions through Spill
Learning and development – £1,000 personal development budget to help you grow in your role.
Private health care - Enjoy all the benefits AXA has to offer, including reduced gym memberships and medical history disregarded
Medical cash plan - To help you with the costs of dental and optical expenses
Life insurance and Income Protection- four times your annual salary for peace of mind
Matched pension contributions up to 5%
25 days holiday - plus bank holidays, well‑being days and volunteering days
Enhanced Parental Leave – enhanced maternity, paternity and adoption pay.