Principal Full Stack JavaScript Engineer

Hedgehog Lab; Leeds; Hybrid; GBP 65,000 - 90,000; Full time

Job summary

A digital product consultancy is seeking a Principal Full Stack JavaScript Engineer to join their Engineering team in Leeds. In this hands-on role, you will lead the modernization of a monolithic JavaScript platform, breaking it down into structured components while collaborating with senior engineers. You will contribute to architectural decisions and operational readiness in a flexible working environment. Ideal candidates will have deep expertise in JavaScript and strong full-stack experience. The position offers a supportive and collaborative culture along with various benefits including annual leave and well-being support.

Benefits

28 days of annual leave plus bank holidays

5 Impact Days per year for L&D

Flexible working environment

Enhanced parental policy

Annual well-being budget

Mental health support

Company-supplied Apple Mac

Qualifications

• Strong full-stack experience, including Node.js and API architecture.
• Comfortable working in small, flat teams with little hierarchy.
• Experience with Google Cloud and modern deployment platforms.

Responsibilities

• Lead hands-on full-stack engineering across a JavaScript platform.
• Break down an existing monolithic system into structured components.
• Work closely with senior client engineers to influence technical direction.

Skills

Deep expertise in JavaScript

Strong full-stack experience

Confident communicator

Experience with Node.js

Tools

Google Cloud

Vercel

Job description

We're growing our Engineering team to strengthen our ability to deliver world-class digital products for our clients. As a Principal Full Stack JavaScript Engineer, you'll join a small, highly technical group tackling a complex transformation: breaking down a monolithic JavaScript platform into clearer, modern components. This is an individual contributor role for someone who thrives on problem-solving, can ramp up quickly, and can collaborate confidently with other very strong engineers. You'll be hands-on from day one, helping modernise architecture, improve maintainability, and set the foundations for future technology decisions, all while staying pragmatic and delivery-focused.

What you’ll do

• Lead (hands-on) full-stack engineering across a JavaScript platform, with a strong focus on architecture and problem-solving.
• Break down an existing monolithic system into well-structured components and services.
• Work closely with senior client engineers, ask the right questions, and influence technical direction through evidence and collaboration.
• Support a move from Vercel-hosted deployment towards a Google Cloud future, improving deployment and operational readiness.
• Contribute to authentication modernisation by integrating an identity platform rather than maintaining bespoke authentication.
• Deliver value quickly by quickly understanding the domain, codebase, and priorities.

About the Company

Who is hedgehog lab? hedgehog lab is a digital product consultancy with 20 years of experience. Based in Northern England, we help global brands craft better digital experiences through technical excellence and human‑first collaboration.

Benefits

• 28 days of annual leave plus bank holidays
• 5 Impact Days per year to spend on L&D, volunteering or innovation
• Flexible working environment
• Enhanced parental policy
• Annual wellbeing budget + two days of wellbeing
• Mental health support
• Company-supplied Apple Mac
  Deep expertise in JavaScript (TypeScript a plus).

Qualifications

• Deep expertise in JavaScript (TypeScript a plus).
• Strong full-stack experience, including Node.js and API architecture.
• A pragmatic mindset: you care about quality, but you also deliver outcomes and keep momentum.
• Confident communicator who can hold their own in technical discussions with senior engineers.
• Comfortable working in small, flat teams with little hierarchy and lots of collaboration.

Nice to have

• Experience with Google Cloud (especially identity or auth-related services).
• Experience with Vercel or modern web deployment platforms.
• Interest or experience in open source communities or open source strategy.
• Exposure to geospatial/GIS/mapping products or highly interactive map UIs.