Full-stack Engineer (£90,000 + Equity) at Second Brain AI

Jack & Jill/External ATS; Greater London; On-site; GBP 90,000; Full time

Job summary

A leading AI startup in London is seeking a Full-stack Engineer to build ownership of the interface for their Synthesis platform. You will create user-centric solutions and collaborate with design and product leads to produce high-quality features. Candidates should have around 6 years of experience, predominantly with React and Next.js, and the ability to manage code quality amidst rapid feature delivery. The role offers a salary of £90,000 plus equity, fostering growth in a dynamic environment.

Qualifications

• Approximately 6 years of experience in full-stack roles, especially in high-velocity SaaS products.
• Ability to develop production-ready user interfaces with limited initial design.

Responsibilities

• Build and own the entire dashboard interface including metric views.
• Design and implement user infrastructure like OAuth flows.
• Develop the core Q&A interface for AI-generated explanations.

Skills

Strong product sense

Ownership-oriented mindset

Experience with React

Experience with Next.js

Ability to ship polished interfaces

Job description

This is a job that Jill, our AI Recruiter, is recruiting for on behalf of one of our customers. She will pick the best candidates from Jack's network.

The next step is to speak to Jack.

Full-stack Engineer

Salary: £90,000 + Equity

Company Description: Second Brain AI – VC-backed AI startup

Job Description: Join Second Brain AI as a Full-stack Engineer to build the core interface for our Synthesis platform. You will own the entire dashboard experience, from complex metric visualizations to seamless auth flows. Working at the intersection of UX and high-velocity engineering, you will ship features that define how users interact with our unique AI insights.

Location: London, UK

Why this role is remarkable:

• Take total ownership of the frontend architecture and user experience for a category‑defining AI product from day one.
• Join a high‑velocity, early‑stage environment where you will build unique features like the Project Pulse and advanced explanation traceability.
• Work directly with design and product leadership to translate complex data into polished, intuitive interfaces for sophisticated users.

What you will do:

• Build and own the entire dashboard interface including metric views, advanced drill‑downs, and complex filtering systems.
• Design and implement critical user infrastructure such as OAuth flows, workspace setup, and granular access controls.
• Develop the core Q&A interface, managing everything from input handling to rendering traceable, AI‑generated explanations.

The ideal candidate:

• Has approximately 6 years of experience in full‑stack roles, specifically building high‑velocity SaaS products with React and Next.js.
• Demonstrates a strong product sense and the ability to ship polished, production‑ready interfaces even with limited initial design support.
• Possesses a pragmatic, ownership‑oriented mindset, comfortable balancing rapid feature delivery with long‑term code quality.

Who are Jack & Jill?

Ok, I'll go first. I'm Jack, an AI that gets to know you on a quick call, learning what you're great at and what you want from your career. Then I help you land your dream job by finding unmissable opportunities as they come up, supporting you with applications, interview prep, and moral support.

And I'm Jill, an AI Recruiter who talks to companies to understand who they're looking to hire. Then I recruit from Jack's network, making an introduction when I spot an excellent candidate.

Next steps

Step 1. Visit our website.
Step 2. Click 'Talk to Jack'.
Step 3. Talk to Jack so he can understand your experience and ambitions.
Step 4. Jack will make sure Jill (the AI agent working for the company) considers you for this role.
Step 5. If Jill thinks you're a great fit and her client wants to meet you, they will make the introduction.
Step 6. If not, Jack will find you excellent alternatives. All for free.

We never post fake jobs

This isn't a trick. This is an open role that Jill is currently recruiting for from Jack's network. Sometimes Jill's clients ask her to anonymize their jobs when she advertises them, which means she can't share all the details in the job description. We appreciate this can make them look a bit suspect, but there isn't much we can do about it.

Give Jack a spin! You could land this role. If not, most people find him incredibly helpful with their job search, and we're giving his services away for free.