Senior/Principal Full Stack Software Engineer

New Today

We are currently working with an ambitious and well-funded early-stage B2B SaaS company that’s building something genuinely transformative in their category. As they enter a critical phase of growth, they’re looking to hire a Senior or Principal Full-Stack Software Engineer to help lay the technical foundations of their platform and influence both the engineering direction and long-term product strategy.
This is a high-impact role offering direct collaboration with cross-functional teams, including senior leadership and the CEO. The successful candidate will play a key part in shaping architecture, scaling infrastructure, and delivering features that add real value to users.
Key Responsibilities:
Design and implement scalable, secure, and high-performance systems.
Own and evolve core parts of the platform architecture.
Collaborate with product, commercial, and leadership teams to align technical delivery with strategic goals.
Write clean, maintainable code across the full stack and contribute to reviews and debugging.
Bring new ideas and best practices to continuously elevate engineering standards.
Ideal Experience:
5+ years of experience working with JavaScript/TypeScript as a full-stack engineer.
Experience leading projects or teams in a technical capacity.
Previous exposure to early-stage startups, ideally in B2B SaaS.
Strong proficiency in modern front-end frameworks (particularly React).
Experience designing and integrating REST or GraphQL APIs (bonus if you’ve built SDKs or documentation).
Solid understanding of SQL and NoSQL databases and backend architecture.
Familiarity with cloud platforms such as AWS, Azure, or GCP.
A pragmatic, product-first mindset—someone who values simple solutions and rapid iteration.
Strong collaboration and communication skills.
What's on offer?
Competitive salary
25 days holiday + bank holidays
Share options in a fast-growing business
Private healthcare (including dental and optical)
Flexible working (remote or hybrid – dog-friendly office in London available)
Strong career development and influence in a key hire
PLEASE NOTE
UK right to work required – unfortunately, visa sponsorship isn’t available.
The team is passionate about , , and building an environment where everyone can thrive and do their best work.
If you're a hands on engineer excited by the idea of helping build a product from the ground up and want to join a team that values innovation, ownership, and velocity we would love to hear from you.
Apply
Location:
London
Job Type:
FullTime

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