Senior/Principal Full Stack Software Engineer

New Yesterday

Job Description

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 diversity, inclusion, 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.

Location:
City Of London
Job Type:
FullTime
Category:
Technology

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