FullStack Engineer (React, Python/FastAPI, Shopify App)

Top 3 reasons to join us

• We are flexible, don't expect you to be in office.
• No politics, respectful and straightforward.
• We iterate fast and are curious.

Job description

Finding something that actually fits online can be frustrating. We're on a mission to change that with AI fit assistance for lingerie and apparel brands: a chat assistant and sizing quizzes that are live on real stores today. We're looking for a Full-Stack Product Engineer to help us scale it.

Position Overview

• We're looking for an experienced Full-Stack Product Engineer to join our team working on our AI fit-assistance platform for lingerie and apparel brands. You'll be responsible for building and owning the client-facing half of Brarista: the integrations that connect us to the tools our clients already run on, the dashboard they live in, the flows that take a new client from signed to live, and the compliance and cost optimisation work that lets us sell to bigger brands and to become cash-positive.
• If something makes onboarding faster, wins us more clients, or shows clients what Brarista is doing for their revenue, that's yours.
• We're small and moving fast, and there's a lot of blank paper.

You will be the person scaling us up from software that works well on a handful of stores into an operation a non-technical person can roll out to many.

→ Contractor, full-time. 12 month contract with an initial 6 month trial.
→ Location: Anywhere in the world
→ Working timezone: UK 9am - 7pm window
→ Team: Third engineer, joining two founding engineers and the founder
→ Ideal starting date: ASAP in late September/mid October. Applications considered on a rolling basis, so apply early. This posting may close early.

Job scope:

Treat this as a guideline rather than a boundary. We’re a start-up, and everyone joins in when there’s a problem to solve.

1. Integrations - connecting us to the tools our clients already use.

• Shopify first, including the App we’re building now. Then Gorgias, putting our fit assistant inside the helpdesks our clients’ support teams work in every day. After that, analytics and lifecycle tools, so our data lands where clients already look at their numbers. You’ll help decide what we integrate next, not just build what’s handed to you.

2. Client onboarding efficiency.

• Bringing a client live currently takes too many manual steps and too much engineering time. Your job is to turn it into a workflow a non-technical person can run start to finish, from signed contract to live widget: catalogue import, size chart setup, brand configuration, testing, go-live. This is the highest-leverage thing you’ll do, and it’s what lets us take on more clients without adding people.

3. The client dashboard, its analytics, and how it makes money.

• Our dashboard shows clients their funnel, revenue attribution, conversations and quiz insights. You’ll build on that and own the monetisation surface alongside the founder: plans, feature gating, usage metering, AI credits, overage, upgrade flows. Deciding what sits behind the paywall is part of the job, not a decision handed to you. The bar isn’t “does the feature work”, it’s “does this make the value obvious enough that a client upgrades”.

4. Our MCP server.

• So we can ask questions about client performance in plain English and get live answers, instead of clicking through dashboards. A spec exists; you’ll build it and extend it as our data grows.

5. Compliance that unlocks deals.

• The bigger the client, the more they ask before signing: security questionnaires, DPAs, data-processing details, evidence we handle their shoppers’ data properly. You’ll own the engineering side of that and the client-facing responses.
• In practice: building the data export and deletion flows Shopify and GDPR require, keeping our data inventory and sub-processor list current as we add integrations, supporting the ISO 27001 work already in progress, and meeting Shopify’s protected customer data requirements for the App Store launch. When a client’s legal team sends a questionnaire, you answer it, and when the answer is “we don’t do that yet”, you build it.
• This isn’t a paperwork job. It’s the difference between winning an enterprise client and losing one.

6. Cost and quality as we scale.

• Every conversation costs us money in AI and infrastructure. Keeping that curve flatter than our revenue curve is what gets us to cash-positive, so you’ll watch what we spend on GCP and MongoDB and engineer it down. Alongside that: automated tests around the logic that matters most, sizing and billing above all, and supporting pen testing when clients ask for it.

And running through all of it: you’ll sit in on product feedback sessions with clients alongside the founder, hearing directly what’s confusing, what’s missing, and what they’d pay for. We think engineers build better products when they hear the complaints themselves rather than through a summary.

Your skills and experience

Technical skillsets that are required for the role:

• 4+ years building full-stack products - React/TypeScript on the front, Python (FastAPI) and MongoDB behind it. You've owned features end to end.
• Real UX instincts. You notice when a flow has one step too many. You'd rather ship a simpler thing than a configurable thing. When you watch someone use what you built and they hesitate, you change it.
• Integration experience, and you know what makes them fragile: webhooks arriving twice or out of order, tokens expiring, rate limits, data that doesn't reconcile.
• Fast reflexes on client-facing work. When a client hits a problem you can turn something around today rather than next sprint, without leaving a mess behind.
• AI coding tools as your default. Our whole team works with Cursor and Claude Code; a lot of our code is AI-authored under human review. It's how we work, not a bonus point.
• Compliance without being precious about it. Security questionnaires and data-handling rules are part of selling to serious clients, a constraint to engineer around, not an interruption.
• Comfortable talking to customers. You'll be in feedback calls, and we want your questions in them.
• Strong written and spoken English - you'll work directly with UK-based colleagues and international clients.

Nice to have:

• Shopify ecosystem experience - apps, App Bridge, Polaris, theme extensions
• Helpdesk or CX integrations: Gorgias, Zendesk, Intercom
• Analytics and attribution tooling: GA4, Klaviyo, Triple Whale
• SaaS billing and usage metering - Stripe, GoCardless, credit systems
• GDPR, ISO 27001 or SOC 2 experience - implementing controls, not just reading about them
• Experience answering client security questionnaires or handling DPAs
• E-commerce or fashion-tech background
• Previous exposure to FinOps on GCP and Mongo
• Previous exposure to pen testing 
• Previous exposure to automated testing, with a good instinct for edge-case logic 

Soft skillsets that are appreciated at Brarista:

• Adaptable, pragmatic and collaborative, with experience working in a fast-moving start-up environment
• Care genuinely about quality and have attention to detail
• Open communication and transparency, especially working async
• Motivated by the prospect of solving a real problem for women's comfort and confidence
• Be responsive, very responsive 

Why you'll love working here

How you think

• You handle ambiguity. Most of what you build here starts as a rough problem, not a spec. You're comfortable working out what the thing should be, asking the questions that clear the fog, and moving before everything is certain.
• You think in systems, not job titles. You don't say "I only do backend" or "that's a frontend ticket." You follow a problem from the database through the interface to the client's revenue, because that's usually where the answer is. Product, full-stack, customer impact: one continuous thing.
• You learn fast, and you use AI to learn faster. Never built an MCP server? Not a problem, we want someone who'll understand it and ship one quickly. The skill isn't knowing everything already, it's knowing which questions to ask: what should this actually do, why is this the right approach, what's the smallest version that works, how do I test it, how do I build it in steps.
• You have high ownership. Our CEO is non-technical and still plans, designs, codes, tests and releases whole features, while running sales, fundraising and operations. That's the standard here. Be the CEO of your own career: own outcomes, not tasks, and don't wait to be chased.

How we work

• Remote and async. No layers, no middle management, no one to route your idea through.
• Goal-first: we care about what ships and what it does for clients. We don't do office politics, mandatory socials, or ceremony for its own sake. We do care about doing the work well and getting better at it, and you'll be surrounded by people who want the same.
• We move fast. If you want a predictable 9-to-5 with a fully-specified backlog, we're honestly not the right fit.

What you'll get:

• Be a core part of a high-potential tech start-up with software already live on real stores
• Direct access to the founder and founding engineers, with real ownership over what you build
• Room to shape the product roadmap, not just deliver tickets

What success looks like

• Month 1 - you've shipped client-facing changes to the dashboard and you understand how a client goes from signup to live.
• Month 3 - client onboarding is meaningfully faster and needs less engineering; Gorgias is live; the MCP server is answering real questions about client performance.
• Month 6 - a non-technical team member can onboard a client end to end, clients can see their Brarista revenue impact without asking us, we've shipped a monetisation change that moved revenue, and we can answer an enterprise security questionnaire in days rather than weeks.