---
title: 'Senior Backend Engineer at CardNexus'
canonical: 'https://feeny.ai/job/senior-backend-engineer-cardnexus-europe-0765t1c4x4pk'
type: 'job'
last_seen: '2026-09-09'
---

# Senior Backend Engineer at CardNexus

- **Company:** CardNexus
- **Location:** Europe
- **Employment:** full-time
- **Work type:** remote
- **Posted:** 2025-03-12
- **Last confirmed live:** 2026-09-09
- **Apply:** https://jobs.gem.com/cardnexus/am9icG9zdDrVgJaj_-E6AXpvBZDMfseF

## Job description

## Role Overview

As a Senior Backend Engineer at CardNexus, you'll play a pivotal role in designing and implementing the architecture for our all-in-one TCG platform. As an early employee, you'll have the autonomy to shape our systems and infrastructure, ensuring scalability, performance, and reliability for a high-traffic marketplace. We're fostering a culture of gamers, so if you love TCGs or are a fan of gaming, you'll feel right at home.

As a remote-first company, CardNexus offers you the chance to collaborate with a diverse, global team across multiple time zones and cultures. You'll report to a supportive and experienced team while making a direct, visible impact on our growing TCG community. Whether you're located in Europe or the US, this role provides the flexibility to drive meaningful change from wherever you call home.

## What You’ll Do

As a Senior Backend Engineer, you will take full ownership of backend architecture, from problem definition to implementation and optimization. You will be responsible for delivering high-performance, scalable solutions for a high-traffic marketplace, ensuring every feature is built with efficiency, resilience, and maintainability in mind. Over the next 24 months, you will:

- Deliver Complex Features: Lead the implementation of intricate features such as:- Real-time card scanning, inventory management, and trade matching.
- A scalable inventory system capable of handling large user collections efficiently.
- Integration of a Payment Service Provider (PSP) and user wallet system, ensuring secure transactions and seamless payment processing.
- Performance and cost optimization at all levels, ensuring minimal resource usage while maintaining high speed.
- Infrastructure scaling strategies to handle millions of daily requests reliably.
- Optimize for Performance and Cost Efficiency: Ensure that every piece of infrastructure and code is optimized for speed, resource efficiency, and minimal operational cost.
- Scale Infrastructure for High Traffic: Build robust logging, monitoring, and scaling strategies to handle millions of daily requests seamlessly.
- Ensure Security and Compliance: Implement rigorous security measures, including KYC processes, to protect users and maintain trust.
- Streamline CI/CD and DevOps: Enhance deployment pipelines for seamless integration and rapid iteration.
- Solve Broad and Deep Technical Challenges: Leverage your expertise across databases, cloud infrastructure, and backend technologies to deliver cutting-edge solutions.

## What You Bring

- Proven Track Record of Ownership: You take full accountability for projects, seeing them through from conception to delivery, ensuring high-quality results.
- Expertise in High-Traffic Systems: Experience designing and optimizing backends for large-scale, high-volume platforms with demanding performance requirements.
- Deep Database Mastery: Extensive hands-on experience with MongoDB, relational databases, and NoSQL solutions, with a strong ability to optimize queries and data structures for performance and scalability.
- Strong Backend Development Skills: Advanced proficiency in Node.js, TypeScript, and backend architecture.
- Broad Technical Knowledge: Comfort with cloud infrastructure (AWS, GCP), logging, monitoring, caching, and DevOps best practices.
- Efficiency-Driven Mindset: Ability to write clean, optimized code that minimizes execution time and resource consumption.
- Problem-Solving Excellence: Ability to decompose complex challenges into scalable, maintainable solutions with a performance-first approach.
- Fluent Communication: Strong written and spoken English skills, capable of articulating ideas clearly in a collaborative, fast-paced environment. Bonus Points:
- Experience working on a large-scale marketplace with high traffic.
- Expertise in MongoDB optimization and sharding strategies.
- Experience with frontend technologies like React, Next.js.
- Passion for Trading Card Games (TCGs) or gaming culture.

## What We Offer

- Fully Remote Work: Enjoy the freedom to work from anywhere with flexible hours that fit your lifestyle.
- Competitive Compensation: We offer a competitive salary that reflects your skills, expertise, and contributions.
- Ownership Opportunities: Access early equity as a core team member, shaping the future of CardNexus.
- Professional Growth: Collaborate with a passionate team of TCG enthusiasts and tech experts to tackle cutting-edge challenges.
- Innovative Culture: Join a gamer-centric environment that celebrates creativity, gaming, and technology.
- Impactful Work: Play a key role in transforming the $15B TCG market with tools that truly make a difference for the community.

## About CardNexus

## Company Overview
- **One-liner**: CardNexus is an all-in-one, mobile-native platform for trading card game (TCG) players, collectors, and investors, combining inventory management, a peer-to-peer marketplace, and AI-powered card scanning.
- **Entity Type**: Private (Partnership; Pre-seed stage)
- **Headquarters**: Bordeaux (Le Bouscat), France
- **Founded**: November 2024
- **Founders**: Julie Le Soymier (Co-founder & CPO), Gaultier Romon (Co-founder & CTO), Tristan Foureur (Co-founder & CEO)

## Core Business
- **Primary Industry**: Internet Marketplace Platforms / Trading Card Game (TCG) Ecosystem
- **Target Customers**: TCG players, collectors, and investors (B2C); community-driven platform serving casual deck-slingers to meticulous collectors across 12+ TCGs.
- **Mission / Purpose**: "To build the home TCGs deserve" — a unified ecosystem where every card, player, and passion connects, giving niche communities the spotlight they deserve.

## Products & Services
- **CardNexus Web SaaS**: A multi-game inventory manager that launched in June 2025, enabling users to track collections, view real-time valuations, and list items for sale.
- **CardNexus Mobile App** (iOS & Android): Launched February 2026, featuring an offline AI card scanner for instant cataloging, real-time price checks, and on-the-go inventory updates.
- **Peer-to-Peer Marketplace**: Launched March 2026, allowing users to set their own prices, choose buyers, and complete sales with verified listings and protected transactions.
- **Open API**: Enables community-led integrations and third-party tools to interact with the platform’s data and trade matching.

## Market Standing
- **Valuation / Market Cap**: Not disclosed (reports of ~$4.04M total funding raised)
- **Key Metric**: 50,000+ registered users; 50M+ cards inventoried; active sellers in 30+ countries; 35% month-over-month user growth.
- **Notable Investors / Partners**: F4 Fund, Aquiti Gestion, Financiere Saint James, Motier Ventures, OPRTRS and 4 other investors.
- **Growth Signals**: Rapid adoption since beta launch in 2025; first mobile-native, multi-TCG platform; expanding games roster (Magic, Pokémon, Flesh and Blood, Lorcana, One Piece, Sorcery, Star Wars: Unlimited, Riftbound, Grand Archive, and more); 8 employees growing at +12.5% monthly in headcount.

## Competitive Advantages
- **First-Mover as Multi-TCG Mobile Platform**: Unlike legacy tools built for a single game (e.g., only Magic or only Pokémon), CardNexus is the first platform to natively support 12+ TCGs on mobile with a unified interface.
- **AI Offline Scanning**: Proprietary AI card scanner works offline, enabling instant collection entry without an internet connection — a key differentiator for events and trade shows.
- **Integrated Marketplace + Community**: Combines inventory tracking, real-time pricing, smart trade matching, and a peer-to-peer marketplace in one seamless app, reducing fragmentation for users.
- **Community-Led Roadmap & Open API**: Actively develops features based on user feedback and provides an API for external developers, building a sticky ecosystem.

## Strategic Focus
- **Current Priorities**: Scaling the user base beyond 50k; expanding game coverage; deepening marketplace liquidity (active sellers in 30+ countries); enhancing AI scanning accuracy and speed; building out the engineering team to support rapid product iteration.
- **Direction for Growth**: Become the default operating system for the global TCG community — managing everything from inventory to trading to social connection — while maintaining a lean, remote-friendly team.

## Why Work Here
- **Culture Highlights**: "One Community. All Realms." — emphasis on shared passion for TCGs, collaboration, and giving niche communities a voice. The team is small (9 people) and highly mission-driven.
- **Remote / Hybrid Policy**: Distributed workforce across France, Belgium, South Korea, and Spain; likely a remote-first culture with occasional co-location (HQ in Bordeaux, France).
- **Engineering Culture**: Heavy technical DNA — Co-founder & CTO (Gaultier Romon) is hands-on; team has 44% in technical roles (including Founding Principal Engineer); opportunity to own major features from day one.
- **Notable Perks**: Working on a product that serves a passionate, growing global community; chance to shape the platform from early stage; involvement in cutting-edge AI (offline scanning, computer vision); flat hierarchy and high autonomy.

## Sources
1. [cardnexus.com - About](https://cardnexus.com/en/about)
2. [cardnexus.com - Homepage](https://cardnexus.com/en)
3. [linkedin.com - CardNexus Company Page](https://linkedin.com/company/cardnexus)
4. [cbinsights.com - CardNexus Profile](https://www.cbinsights.com/company/cardnexus)
5. [cardnexus.com - Press Kit](https://cardnexus.com/en/press-kit)

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