Full Stack Tech Lead

Job Title: Full Stack Tech Lead
Location: Central London
Salary/Rate: £650 Inside IR35
Job Type: Contract

Role Overview

We are looking for a highly experienced and technically profound Full Stack Tech Lead to drive the architecture and execution of our core technology stack. You will serve as the technical authority for the team, building and evolving a large-scale platform built on C#/.NET and Next.js, leveraging the full capabilities of Google Cloud Platform (GCP).

This role requires a blend of hands-on coding (approximately 60-75%), strategic architectural thinking, and dedicated mentorship. We are looking for a leader who can operate confidently in a high-stakes environment and share ownership of complex technical decisions alongside our existing leadership team to ensure we deliver robust, scalable, and maintainable solutions.

Key Responsibilities

• Architectural Leadership: Lead the design and implementation of C#/.NET backend services, APIs, and core business logic. Define and enforce the technical vision and design patterns across the full stack.
• System Integration: Oversee the seamless integration with external financial, risk, and payment services, ensuring high reliability, security, and data integrity.
• Collaborative Decision Making: Partner with existing technical leadership to share ownership of complex architectural decisions, balancing innovation with platform stability.
• Team Leadership & Mentorship: Lead, coach, and motivate a team of developers, conducting regular code reviews and facilitating knowledge sharing to raise the overall engineering bar.
• Strategic Planning: Collaborate with Product Owners to refine the technical roadmap, estimate complex features, and manage technical debt within an Agile framework.
• Full Stack Development: Remain hands-on with development, implementing complex features and solving critical performance bottlenecks across the C# and Next.js stack.
• GCP Platform Strategy: Own the deployment, monitoring, and scaling strategy on Google Cloud Platform, ensuring the platform can handle large-scale traffic and data.
• Process Improvement: Champion Agile methodologies, optimising CI/CD pipelines and establishing metrics for system health and engineering velocity.

Requirements

• 7 years of progressive experience in software development, with significant time spent in an architectural or technical leadership capacity.
• Expert-level proficiency in C# and the .NET framework for designing and implementing high-throughput backend services and core business logic.
• Proven track record of building large-scale platforms and managing the complexities that come with high-volume environments.
• Hands-on experience with external integrations, specifically involving financial, risk management, or payment gateway APIs.
• Expert-level proficiency in Next.js/React, including performance optimisation and server-side rendering architecture.
• Extensive experience with Google Cloud Platform (GCP), including cloud-native architecture, cost optimisation, and security best practices.
• Exceptional leadership presence and the ability to drive consensus on technical direction while working collaboratively with other senior stakeholders.

Nice-to-Have Skills

• Practical experience with Infrastructure as Code (IaC), for managing GCP resources.
• Experience with large-scale data processing or streaming technologies on GCP.

Disclaimer
Notwithstanding any guidelines given to level of experience sought, we will consider candidates from outside this range if they can demonstrate the necessary competencies.
Square One is acting as both an employment agency and an employment business, and is an equal opportunities recruitment business. Square One embraces diversity and will treat everyone equally. Please see our website for our full diversity statement.