Senior Full Stack Engineer

Build Technology That Changes How Businesses Operate

Avallo partners with private equity firms and their portfolio companies to solve complex operational and commercial problems through technology.

We build new digital products, modernise critical platforms, automate business processes with AI and create the technical foundations companies need to scale.

This is not traditional consulting. We do not produce recommendations and leave clients to execute them. Our teams work directly with business leaders, operators and engineers to define the problem, build the solution and deliver measurable results.

• Product strategy and development
• Software engineering
• AI and automation
• Data and analytics
• Technology-enabled operational improvement

The Role

We are hiring a Senior Full Stack Engineer to join our core engineering team.

You will take ownership of technically demanding projects across a small number of client engagements, working alongside experienced technology leaders, product specialists and client engineering teams.

The role is hands-on. You will design systems, write production code, make architectural decisions and ship software used in real operating environments.

You will:

• Build and launch new applications from the ground up
• Modernise complex and business-critical legacy platforms
• Develop AI-enabled products, workflows and automation
• Design secure, scalable cloud infrastructure
• Integrate with existing systems, APIs and data platforms
• Work directly with founders, executives and senior technical stakeholders
• Turn ambiguous business problems into clear technical solutions
• Challenge requirements and propose better approaches where necessary
• Help shape Avallo's engineering standards, practices and future team

You will work across a broader range of technologies and business models than you would typically encounter in a single-product company. You will also have direct visibility into how technical decisions affect revenue, operations, customer experience and company value.

What You Will Build

Our engagements vary by company and industry. Typical projects include:

• Customer portals and enterprise web applications
• AI-powered operational workflows
• Internal automation and productivity platforms
• API platforms and third-party integrations
• Payment and financial technology systems
• Data and operational management platforms
• Legacy platform migrations and modernisation programmes

The common thread is impact: the systems we build must perform reliably, solve a meaningful problem and create measurable value.

TechnologyWe hire engineers with strong technical judgement rather than narrow framework expertise. Our current stack includes:

Frontend

React, Next.js, TypeScript and Tailwind CSS

Backend

Node.js, NestJS, TypeScript, Python, REST and GraphQL

Data

PostgreSQL, Redis and SQL-based data platforms

Cloud and Infrastructure

AWS, Docker, Terraform, ECS, S3, RDS, CloudFront and GitHub Actions

AI and Automation

OpenAI, Anthropic, document processing, agentic workflows and AI-assisted software development

Our stack will continue to evolve. We expect senior engineers to help us decide what should change and why.

What We Are Looking For

We are looking for engineers who combine strong technical ability with ownership, pace and commercial judgement.

You are likely to succeed at Avallo if you:

• Have a strong track record of shipping production-grade web applications
• Take responsibility for outcomes, not only assigned tasks
• Write clear, maintainable and reliable software
• Can understand unfamiliar codebases and industries quickly
• Make pragmatic technical decisions without lowering standards
• Think about users, operations and commercial impact alongside implementation
• Communicate clearly with both technical and non-technical stakeholders
• Remain effective when requirements are incomplete or priorities change
• Use AI tools meaningfully to improve the speed and quality of your work
• Are comfortable operating with autonomy and being accountable for your decisions

You will ideally have experience with several of the following

• TypeScript, Node.js, React and Next.js
• NestJS or comparable backend frameworks
• PostgreSQL, Redis and relational databases
• AWS, Docker and Terraform
• REST APIs and distributed integrations
• CI/CD and automated testing
• Event-driven architecture and distributed systems

Experience building with LLMs, automation platforms or document-processing systems is a strong advantage.

Experience in financial services, fintech, payments or another regulated industry is useful, but not essential.

How We Operate

Avallo is a growing business with high expectations and limited bureaucracy.

You will have meaningful influence over the work, the technology and how the engineering function develops. In return, we expect initiative, sound judgement and a high level of personal ownership.

Our operating principles are straightforward:

• Own the outcome: Take responsibility for the result, not only your part of the implementation.
• Move with urgency: Make decisions, ship useful software and improve it through real feedback.
• Protect quality: Speed matters, but reliability, security and client trust matter more.
• Stay close to the problem: Understand the business context before choosing the technical solution.
• Use the best tools available: We use AI extensively across engineering and expect the team to keep improving how it is applied.
• Challenge constructively: Senior engineers are expected to question weak assumptions and raise the standard of the work around them.

What We Offer

• Performance-related bonus
• Equity opportunity
• Remote-first working across the UK
• Flexible working arrangements
• 25 days of annual leave, plus bank holidays
• Company pension
• High-quality equipment and modern development tools
• Access to leading AI engineering platforms
• Direct exposure to founders, CEOs and private equity operating teams
• The opportunity to work across multiple businesses and industries
• Significant autonomy and influence as the engineering team grows

Why Avallo?

Most engineering roles place you inside one product, one industry and one roadmap.

At Avallo, you will work across businesses at important stages of growth and transformation. You will solve difficult technical problems, work directly with senior decision-makers and see the commercial effect of what you build.

You will also join early enough to influence how the engineering organisation develops: its standards, architecture, tooling, hiring and culture.

We are building a team for engineers who want more responsibility, more variety and a closer connection between their work and the performance of the businesses they support.

If you are technically strong, commercially curious and motivated by ownership, we would like to hear from you.