---
title: 'Senior Engineer, Fullstack - Growth at Primer.io'
canonical: 'https://feeny.ai/job/senior-engineer-fullstack-growth-primer-io-portugal-vcscm5a1495c'
type: 'job'
last_seen: '2026-09-09'
---

# Senior Engineer, Fullstack - Growth at Primer.io

- **Company:** Primer.io
- **Location:** Portugal
- **Employment:** full-time
- **Work type:** remote
- **Posted:** 2026-09-08
- **Last confirmed live:** 2026-09-09
- **Apply:** https://jobs.ashbyhq.com/primer.io/e16b862c-7192-4a23-b7c9-e978dd91b137

## Job description

An Introduction to Primer

Primer is the unified infrastructure for global payments. We give finance and payments teams the visibility and control to reduce complexity, improve performance, and capture more revenue - all from a single platform.

Backed by Sofina, Peak XV Partners, ICONIQ, Tencent, Accel, and Balderton, we're building the payments layer the world's best companies rely on.

Watch our showcase > https://primer.io/the-primer-showcase

Read up on our $100m Series C https://www.primer.io/blog/series-c

Learn more about our culture > https://primer.io/careers

Which team will you be joining?

You'll be joining the Growth team, which owns merchant onboarding and activation: everything between a new account and a first live payment. It's a newly formed team taking on a new product area for Primer, so there's a lot of scope to shape both what we build and how.

Primer is remote-first and globally distributed — always will be.

What will you be doing?

- Lead frontend architecture and technical direction for the self-serve onboarding and platform experience, with real ownership over how it's built, not just what gets shipped
- You’ll spend roughly 80% of your hands-on codebase time on frontend and 20% on backend. That split is a guide, not a rule, and it will shift in either direction depending on what we're focused on at the time.
- Partner closely with Design to take onboarding and platform experience from concept to production, shaping the details that decide whether a merchant's first steps with Primer feels effortless or frustrating
- Mentor and raise the bar for the engineers who join the team, you're the person newer engineers learn frontend craft from
- Set frontend conventions and quality standards for a team that's still being built — architecture reviews, code quality, testing approach, all early enough that your calls stick
- Contribute to the Python backend where it's needed to unblock frontend work or ship a feature end to end, without needing deep backend expertise going in

## What we're looking for

- Strong, proven frontend expertise — production experience architecting and building complex frontend applications, not just consuming a design system
- Comfortable being the most senior frontend voice in the room, including pushing back on design or product where the frontend reality demands it
- Some backend experience and a genuine willingness to work in a Python codebase — depth isn't required, but you shouldn't be reluctant to touch it
- Experience mentoring other engineers, ideally including people earlier in their career than you

Nice to have, not required:

- Experience building or integrating payment products
- Experience in a growth, onboarding, or activation-focused product surface

What you should be aware of:

- The team is still forming, so you're inheriting mentoring responsibility for people who haven't been hired yet — the "who" of who you're mentoring is still unknown
- Remote-first, high autonomy, no hand-holding — you're expected to set your own standards, not follow someone else's playbook
- Early-stage team means some ambiguity on process and tooling that a more established team would already have solved

## ✅ A TYPICAL INTERVIEW PROCESS

- An initial intro call with a Talent Partner
- An interview with the Hiring Manager
- Challenge Stage - Contextualised to the role
- A final, values-alignment interview

WHAT'S THE CULTURE LIKE AT PRIMER?

We're building a culture where people can do their best work and be proud of the impact they have. You'll be working with people who are mission-driven, smart, and reflective, and who are genuinely invested in building exceptional products and delivering success for our merchants.

We work remotely, and have done since day one. We believe that building a successful, profitable company goes beyond proximity. We invest in our relationships through great remote working practices and thoughtfully designed face-to-face time, including workations, our annual company retreat, and access to co-working spaces across most major cities.

The work is challenging. Scaleups are a challenge, and building category-defining products is a challenge. But there's a meaningful difference between a challenge and a struggle. At Primer, the right challenge comes with the right support: strong onboarding, a collaborative environment, and a team that is genuinely invested in your success. It's never something you face alone.

## OUR BENEFITS

🌍 We are fully remote and globally distributed; and have been since day one 💰 Competitive share options 🌴 Uncapped holiday, with 25 days minimum to be taken 🗣️ Co-working space access across major cities 📅 Workations & Company Retreat 💻 The best equipment for your role 🏠 £500 towards your home office setup 🔎 Generous learning budget 🏥 Private Medical Insurance 📈 A broad set of additional perks and benefits (depending on location)

DON’T MEET EVERY SINGLE REQUIREMENT?

At Primer, we're dedicated to building a diverse, inclusive, and authentic workplace. If you're excited about this role but your experience doesn't align perfectly with every qualification listed, we encourage you to apply. You may be the right candidate for this or other roles.

Primer is committed to the equal treatment of all current and prospective employees and adopts a zero-tolerance approach to discrimination, regardless of age, disability, sex, sexual orientation, pregnancy and maternity, race or ethnicity, religion or belief, gender identity, marriage and civil partnership, or any other background or belief.

## About Primer.io

## Company Overview
- **One-liner**: Primer provides an AI-powered unified payments infrastructure that lets merchants accept, manage, and optimize every transaction from checkout to payout.
- **Entity Type**: Private – Series C (raised $100M in 2026)
- **Headquarters**: London, United Kingdom
- **Founded**: 2020
- **Founders**: Gabriel Le Roux and Paul Anthony

## Core Business
- **Primary industry**: Payments infrastructure / Fintech
- **Target customers**: B2B – merchants of all sizes (SMB to enterprise), payment and finance teams
- **Mission**: Build the world’s first unified payments infrastructure, making payments a source of growth rather than just a cost of doing business

## Products & Services
- **Primer Platform (Accept, Manage, Optimize)**: A single integration connecting multiple payment providers. Covers acceptance, routing, reconciliation, FX, and fallbacks. Includes no-code Workflows.
- **AI Companion**: An AI agent that learns a merchant’s business, monitors transactions, and optimizes performance end-to-end.
- **Global Accounts**: Helps finance and payments teams manage how money moves across their business.
- **Reconciliation**: Automated transaction tracking from checkout to settlement to uncover revenue opportunities and reduce hidden costs.
- **Fallbacks & Network Tokenization**: Features that boost payment success rates and revenue capture.
- **Primer for Partners**: Enables any service to build into Primer and own their integration.

## Market Standing
- **Valuation**: Not publicly disclosed
- **Key Metric**: Total funding raised – $173M (Seed $4.3M, Series A $18.7M, Series B $50M, Series C $100M) [primer.io/about-us]
- **Notable Investors**: Sofina (lead Series C), ICONIQ (lead Series B), Accel, Balderton, RTP Global, Seedcamp, Speedinvest, Tencent, Peak XV Partners
- **Growth Signals**:
  - 200% year-on-year growth in 2024 [primer.io/about-us]
  - Headcount of 128 employees (+25.5% YoY) [linkedin.com]
  - Operating in 30+ countries across 6 continents
  - Processes billions of dollars in payment volume monthly with 99.99% uptime
  - 95%+ of customer payment volume processed reliably

## Competitive Advantages
- **Unified platform**: Replaces the complexity of managing multiple providers with a single integration and control plane
- **AI-native**: AI Companion provides ongoing optimization, monitoring, and incident response
- **Enterprise-grade security**: PCI-1 & GDPR compliant, SOC2 Type-2 certified
- **Proven scale**: Trusted by global merchants with billions in volume and 99.99% uptime

## Strategic Focus
- Deepen presence in APAC (2024–2025 expansion)
- Continue building AI-native infrastructure for the next generation of payments and finance teams
- Grow the Primer for Partners ecosystem
- Scale the platform with new features like Global Accounts and Reconciliation

## Why Work Here
- **Remote-first since day one**: Team works from 30+ countries with flexible hours; teams align on overlap for collaboration.
- **Culture**: Low ego, high standards, strong ownership, and generous knowledge sharing. Proud of a 4.2 Glassdoor rating.
- **Benefits**: Premium private health insurance (AVIVA in UK; Allianz, Bupa globally); competitive location-based compensation plus equity; wellness and training budget.
- **Growth**: Significant autonomy and opportunities to shape your own path; average hiring process of 27 days.
- **Global retreats**: Company-wide retreats and team workations to bring people together in person.

## Sources
1. [primer.io](https://www.primer.io/)
2. [primer.io/careers](https://primer.io/careers)
3. [primer.io/about-us](https://primer.io/about-us)
4. [linkedin.com](https://uk.linkedin.com/company/primerapi)
5. [jobs.ashbyhq.com](https://jobs.ashbyhq.com/primer.io)

## Other roles at Primer.io

- [Revenue Operations Associate](https://feeny.ai/job/revenue-operations-associate-primer-io-singapore-9xgep3cx6yvy) — Singapore
- [Senior Engineer, Backend - Orchestration](https://feeny.ai/job/senior-engineer-backend-orchestration-primer-io-poland-r9828xtxvszb) — Poland
- [Security Engineer III - Security Operations](https://feeny.ai/job/security-engineer-iii-security-operations-primer-io-united-kingdom-ya1gsz662c07) — United Kingdom
- [Senior Security Engineer](https://feeny.ai/job/senior-security-engineer-primer-io-united-kingdom-5as7t2z1fs28) — United Kingdom
- [Senior Account Executive - East](https://feeny.ai/job/senior-account-executive-east-primer-io-new-york-vtcgddptce28) — New York, NY
- [Software Engineer III, Backend - Protection](https://feeny.ai/job/software-engineer-iii-backend-protection-primer-io-south-africa-yfy2ptb5yxdj) — South Africa
- [Product Marketing Manager](https://feeny.ai/job/product-marketing-manager-primer-io-united-kingdom-cbfmmr4w1ppy) — United Kingdom
- [Business Development Representative - North America](https://feeny.ai/job/business-development-representative-north-america-primer-io-california-0gzyxv39wnc4) — California
- [Software Engineer II, Frontend - Protection](https://feeny.ai/job/software-engineer-ii-frontend-protection-primer-io-hungary-pa46crj5ws3g) — Hungary
- [Staff Engineer, Frontend](https://feeny.ai/job/staff-engineer-frontend-primer-io-united-kingdom-rs7ma5fajp0m) — United Kingdom