Tech Lead - Core Backend (Financial Systems & Architecture)

Bitcoin has become long-term wealth for millions of people — but the financial system still treats it like an edge case. People either sell their Bitcoin and give up long-term conviction, or hold it and accept that their capital is locked and unusable. That gap is not technical anymore. It’s structural.

At 21bitcoin, our mission is to change how Bitcoin fits into real financial life — safely, transparently, and under regulation. We’re building a platform where Bitcoin can be trusted over decades, integrated into serious financial workflows, and used as capital without compromising on security or principles.

🚀 Why join us

21bitcoin is profitable, regulated, and already trusted with significant assets, but still early enough that every strong hire shapes the company. Over the next 1–2 years, we’re focused on turning Bitcoin from a passive store of value into a first-class financial primitive for individuals and businesses in Europe.

You’ll work in a small team of high performers from places like Bitpanda and Scalable Capital, with real ownership, high standards, and no corporate theater. If you’re looking for comfort, this is not the place. If you’re looking for responsibility, intensity, and the chance to help build a €1B+ financial company the right way, you’ll feel at home.

👋 The Role

As Tech Lead – Core Backend, you are one of the technical gravity centers of 21bitcoin.
You design, evolve, and protect the core financial systems that power our broker, custody, and future Bitcoin-backed financial products.

This is not a people-management role.
This is not babysitting tickets.

You are an engineer’s engineer:
a system designer, architectural referee, and hands-on builder who earns trust by writing code, making trade-offs explicit, and raising the technical bar for everyone around you.

🚀 Your Mission

As Tech Lead – Core Backend, you will:

• Design and evolve the core financial architecture
  Ledger, workflows, settlement, broker flows, custody interactions, and the invariants that hold them together.
• Own system-level correctness
  Ensure idempotency, consistency, reconciliation, failure handling, and auditability across event-driven and workflow-based systems.
• Be the architectural referee
  Resolve hard technical trade-offs across domains without centralizing power or slowing teams down.
• Build alongside the team
  You ship production code. You review critical paths. You pair when systems are fragile or concepts unclear.
• Shape AI-native engineering
  Help define how we use agents, AI-assisted development, automated reviews, and system generation — without sacrificing correctness or clarity.
• Translate product ambition into primitives
  Bitcoin-backed loans, principal trading, limit orders, custody abstractions — you help turn these into clean, reusable building blocks.

🎯 What Success Looks Like

• Core financial flows (ledger, broker, custody, settlement) are explicit, correct, and resilient — with invariants enforced in code, not tribal knowledge.
• New products and workflows build on reusable primitives, not copy-pasted logic or cross-domain hacks.
• The core backend enables teams to ship faster with fewer incidents, and architecture discussions are short, pragmatic, and rarely revisited.
• AI tooling measurably increases engineering leverage (throughput, refactoring, test coverage) without degrading correctness or operability.
• You are trusted as an engineer and system designer — influence earned through decisions, code, and judgment, not title.

🛠️ Your Toolbox

You don’t need everything — but you should feel at home with most of this:

Backend & Architecture

• TypeScript / Node.js (NestJS or similar)
• Modular monoliths, event-driven systems, workflow engines
• Ledger systems (double-entry, reservations, settlements)
• Idempotency, outbox patterns, reconciliation strategies

Financial & Broker Systems

• Principal trading flows
• Limit orders, partial fills, settlement gaps
• Custody abstractions (on-chain & off-chain)
• Bitcoin-backed lending or collateralized systems (strong plus)

Infrastructure

• AWS (ECS, RDS/Aurora, SQS/SNS, IAM)
• Infrastructure as Code (Terraform / CDK)
• Observability as a first-class concern

AI-Native Engineering

• AI-assisted coding (Cursor, Claude, agents)
• Automated reviews, refactoring, test generation
• Clear mental models for where AI helps — and where it must not

⭐ What We’re Looking For

To succeed in this role, you should:

We’re looking for a senior backend systems engineer who:

• Has 8+ years of experience designing and operating production systems where correctness, money, or risk actually matter.
• Thinks in invariants, failure modes, and trade-offs — and can explain why a system is built a certain way.
• Has designed or deeply worked on financial or stateful systems (e.g. trading, brokerage, ledgers, settlement, custody, lending, or similarly complex domains).
• Is a hands-on engineer who earns trust by writing, reviewing, and improving real production code — not by owning org charts.
• Believes AI is a force multiplier for senior engineers and actively uses it to scale judgment, throughput, and code quality — while knowing where automation must stop.
• Must be located within ±2 hours of CET timezone
• Being based in or willing to relocate to Munich, Salzburg, or Vienna is a significant advantage (relocation assistance available)

🚀 Why YOU should join 21bitcoin

1. Impact: Shape the future of Bitcoin financial services by leading critical projects and redefining technical standards.
2. Autonomy: Work in a fast-paced startup environment where you have the freedom to drive impactful solutions.
3. Innovation: Build cutting-edge systems using modern tools, languages, and cloud-native infrastructure.
4. Growth: Collaborate with a highly skilled team that values mentorship, learning, and pushing boundaries.

💸 Competitive compensation

🏢 Remote First, with In-Person Magic: We prioritize remote work for flexibility but cherish the power of face-to-face collaboration. Join us at our vibrant hubs in Munich, Salzburg, and Vienna to experience the best of both worlds! We provide relocation assistance.

🕑 Flexible working hours: We value focus time. Encouraging everyone to minimize fixed meetings and leverage asynchronous communication.

Final compensation will be determined based on the candidate's qualifications, skills, previous experience and location.

Apply now and become a key part of the team driving 21bitcoin’s success.

📝 Interview Process

How to apply?

Please reach out to us and include a bit about yourself, your resume/CV, examples of past projects, and a few bullet points about why you’re interested in joining 21bitcoin and what you expect.

BTW: CVs are important, but don't forget to include your favorite Bitcoin meme in the application!

• 🗒️ Resume Review - Portfolio of Work: Drop a link to your portfolio/previous work or CV which we can review (LinkedIn, Github, Twitter, …)
• 📞 Exploratory Call - We'll discuss what excites you about this role and a few questions based on your past experiences
• 🧠 Test assignment - We will share a take home creative assignment with you to work on (usually 1 week time frame)
• 🗣️ Engineering Deep Dive - During the deep dive session, we will discuss specific skills for each role through a case study or a technical interview.
• 👬 Meet Us (Workshop) - During the workshop, we will explore various real-world problems that you will be expected to solve in your role.
• 👍 Decision time!