Sr. Software Engineer, Fullstack (UK) | Firstup Jobs
Sr. Software Engineer, Fullstack (UK)
Remote - UK
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Who We Are

At Firstup, our mission is to improve the employee experience at every moment that matters, large and small. As the communication pipeline for the world's workforce, we now serve 40 of the Fortune 100 companies, reaching and connecting more than 17 million employees daily.

Our employees are experts in the employee experience, workforce communications and technology. 
Joining Firstup means joining a movement to make work better for every worker. As the world’s first intelligent communication platform, Firstup meaningfully engages employees at every moment from hire to retire, and delivers engagement insights to help companies support, promote and retain their talent. Our movement has taken root and is evident in our world-class customer base. Now we need your help. Ready to make a difference in the world?


Job Summary
 
We're looking for a Senior Full Stack Engineer who thrives at the intersection of craft and scale. You'll design and deliver large-scale, multi-tenant cloud services — with a relentless focus on availability, fault-tolerance, and elegant architecture. You'll set the bar for engineering quality and help elevate those around you.

Responsibilities

  • Core Engineering & Ownership: Build and own scalable SaaS applications end-to-end — frontend, backend, and data layers. Write production-grade code that is reliable, readable, efficient, and testable. Raise the bar through thoughtful code reviews and comprehensive documentation.

  • System Architecture: Design future-ready architectures and proactively close gaps before they become problems.

  • Performance & Reliability: Drive system availability and performance — investigate, analyze, and resolve reliability issues across the stack. Recognize opportunities and advocate for better performance and efficiency of software, systems, and processes across teams.

  • Shift Left Testing & Quality: You champion a rigorous 'shift-left' quality culture, embedding comprehensive testing—unit, integration, and contract—early and continuously in the development lifecycle, not as an afterthought.

  • AI Integration: Leverage and advocate for AI-assisted tools (e.g., GitHub Copilot, Claude) to accelerate development while maintaining rigorous engineering judgment and accountability for code correctness.

  • Leadership: Drive team-wide best practices, conduct quality code reviews, and mentor engineers to elevate overall engineering quality.

  • Collaboration (Product & Design): Partner with Product and Design to translate requirements into intuitive UI, making informed technical trade-offs in the face of ambiguity.

  • Collaboration (Engineering Standards): Champion engineering best practices across teams and collaborate on solving complex, high-impact problems.

Minimum Qualifications

  • Bachelor's degree in Computer Science or related field, or equivalent experience.

  • 5+ years building reliable, performant applications and microservices in production environments. Proven full stack fluency - you're comfortable across frontend, backend, and the database layer. 

  • A polyglot mindset — you evolve with the tech. Familiarity with Ruby on Rails, TypeScript, Node.js, or React.js is a strong plus.

  • Proven full-stack experience across frontend (React.js), backend, and database layers.

  • Technical depth in at least one engineering domain: distributed systems, multi-tenant SaaS, application databases, networking, security, serverless, event streaming, or similar.

  • A genuine drive to build beautiful, intuitive products with the customer always in focus. Innate curiosity — you love learning and have a desire to teach and lift others. Strong communication skills and openness to collaborative idea-sharing across teams.

    • Preferred Qualifications:

  • Core Stack Experience: Familiarity with Ruby (including Ruby on Rails), TypeScript, Node.js, or React.js is a strong plus.
    • Why Firstup?
     
    Because you care - about people, the work you do, and the connections you make. Work is such a large part of life; it only makes sense to make it awesome.
     
    If you want to engage brilliant minds in a high-growth and inclusive environment where ideas are rewarded regardless of who they come from, join us. This is a rapidly changing space so if you thrive on ambiguity, are hungry for a challenge, and have the guts to speak your mind, you could be a perfect fit.
     
    We offer an excellent PTO program, great health benefits, a casual and friendly environment, remote work, and a leadership team who truly believes in your growth – both personally and professionally.
     
    Firstup is committed to providing equal employment opportunities to all applicants for employment and to all employees, without regard to race, color, religion, gender, sexual orientation, gender identity or expression, national origin, age, protected disability, veteran status, or any other protected status in accordance with applicable federal, state or local laws.


    #LI-TM1
    #LI-Remote

    • To improve the employee experience at every moment that matters, large and small.

    • To make work better for every worker.

      • Every employee is an owner
      • Leadership is in our build
      • We win as a team
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    Working at Firstup

    Overall Culture Score

    4.8/5

    CEO Score

    Bill Schuh
    Top
    5%

    Bill Schuh
    Top 5% of Similar Sized Companies on Comparably

    Awards

    Reviews from current employees

    Our team is full of talented individuals with different backgrounds. I feel like we are all committed to helping each other out, jumping in when someone needs something and they are also funny, easy to work with and great people.
    I think the pay is fair and within market. The variable opportunity is also fair and is incentivizing to drive performance.
    We are a fully-remote organization with a few exceptions. I am used to working from home and comfortable managing my schedule and reaching out when I need something. The people here are really passionate about what we do and building great products and taking care of our customers.

    Diversity at Firstup

    Top 10%

    Gender Score

    As rated by current employees on Comparably

    Top 10%

    Diversity Score

    As rated by current employees on Comparably

    Perks and Benefits

    Health & Wellness
    Dental Insurance
    Vision Insurance
    Health Insurance
    Life Insurance
    Paid Time Off
    PTO / Vacation Policy
    Paid Holidays
    Maternity / Paternity Leave
    Financial Benefits
    401K / Retirement Plan
    Performance Bonus
    Office Perks
    Company Social Outings
    Unique Office Space
    Legal Assistance
    Work From Home Policy

    eNPS

    70
    eNPS Score
    75%Promoters
    20%Passive
    5%Detractors

    Firstup's Employee Net Promoter Score (eNPS) is 70, as rated by 65 employees. This means 75% of Firstup employees would encourage their friends to become coworkers today.

    5 Cool Reasons to Work at Firstup

    1. Join us to create. Be a part of the workforce transforming the employee experience.
    2. We are the communication pipeline for the world! 40 of the Fortune 100 companies use Firstups's platform.
    3. As the experts in workforce comms, Firstup employees are creating change and having fun doing it!
    4. We strive daily to weave DEIB into our culture through our processes, people and decision-making.
    5. We offer world-class benefits, including our "Fruity Umbrella Drink Bonus." You get paid to take a vacation.