---
title: 'Senior Backend Engineer at Project Eleven'
canonical: 'https://feeny.ai/job/senior-backend-engineer-project-eleven-united-kingdom-65chgqvvbc1k'
type: 'job'
last_seen: '2026-10-15'
---

# Senior Backend Engineer at Project Eleven

- **Company:** Project Eleven
- **Location:** United Kingdom
- **Employment:** full-time
- **Work type:** remote
- **Posted:** 2025-12-19
- **Last confirmed live:** 2026-10-15
- **Apply:** https://jobs.ashbyhq.com/projecteleven/d42994cb-1b6e-4e89-9358-e49be85c5caf

## Job description

## About Project Eleven

Project Eleven is an applied lab of builders and technologists working at the intersection of quantum computing and cryptography. We build impactful solutions that push the digital-asset ecosystem to a more secure future. Our focus is post-quantum migration: upgrading wallets, identity, and settlement rails to quantum-safe primitives without breaking UX, composability, and developer workflows. Our mission is to future-proof digital assets and preserve self-sovereignty in a post-quantum world. We do that by building the canonical tooling and products teams can adopt: crypto-agile infrastructure, reference implementations, and integrations that fit real constraints like latency, cost, compatibility, key rotation, and recovery. We work with leading ecosystems to make this migration real through products we build, audits, testnets, and cutting edge research. The vision we are have is clear: a proven upgrade path, production-ready tooling and users retaining control of their assets and identity, before CRQC exists.

## The role

We're looking for a Senior Backend Engineer to join our growing Product Engineering team. You'll play a pivotal role in building the canonical infrastructure that protects institutional digital-asset operations in a post-quantum world. This role is a full-time, fully remote position in Europe (GMT to GMT+2).

## What you'll be responsible for

- Owning and evolving security-critical backend services at the core of our institutional product
- Designing and implementing systems with strict correctness, durability, and auditability guarantees
- Enforcing strict security boundaries around sensitive operations and data
- Defining and upholding API stability, versioning, and backward-compatibility policies
- Contributing to internal security standards, threat modeling, and engineering best practices
- Partnering with our cryptography and research engineers to bring novel primitives into production systems

## What you bring

- Strong proficiency in Rust and TypeScript (ideally both)
- Experience building performant backend services, APIs, and libraries at production scale
- Experience designing systems with strong security, durability, or correctness requirements e.g. financial systems, key management, identity, custody, or other regulated infrastructure
- Solid applied cryptography fundamentals: signing, encryption, secrets management, key handling
- Good knowledge of CI/CD, service deployments, and containerisation
- High competency with automated testing (unit, integration, and e2e)
- Strong English communication

## What we'd love to see

- Experience building or operating institutional infrastructure: custody platforms, HSM-backed systems, KMS, or similar high-assurance systems
- Familiarity with threshold signing, MPC, or HSM integration patterns
- Exposure to compliance frameworks (SOC 2, ISO 27001) and audit-friendly system design
- Experience with post-quantum cryptography or the operational implications of migrating cryptographic primitives
- Experience developing and maintaining long-lived libraries or protocols with strong backward-compatibility requirements
- Open-source contributions to cryptography, security, or related infrastructure

## Equal Opportunity

We are committed to equal employment opportunity and believe that diverse teams build better products. All qualified applicants will receive consideration without regard to any protected characteristic under applicable law.

## About Project Eleven

## Company Overview
- **One-liner**: Project Eleven builds post-quantum cryptographic infrastructure and tooling to secure digital assets against emerging quantum threats.
- **Entity Type**: Private (Series A)
- **Headquarters**: New York, United States
- **Founded**: 2024
- **Founders**: Alex Pruden (CEO & Co-Founder), Conor Deegan (CTO & Co-Founder) (LinkedIn also lists Leeor Mushin as Co-Founder)

## Core Business
- Primary industry: Post-quantum cryptography, blockchain security, digital asset infrastructure
- Target customers: Enterprises, blockchain protocols, financial institutions, digital asset custodians (B2B)
- Mission: To prepare the digital asset ecosystem for the quantum era by bridging advanced post-quantum research with real-world implementations

## Products & Services
- **libqc**: Open-source library for post-quantum cryptography migration, providing crypto-agile wallet infrastructure
- **Quantum Vault**: Audited reference implementation for account abstraction (ERC-4337) and Bitcoin vault security, designed for a quantum-safe future
- **Bitcoin Risq List**: A dataset used by Google, Stanford, and the Ethereum Foundation to flag quantum-vulnerable Bitcoin addresses
- **The Quantum Threat to Blockchains – 2026 Report**: Comprehensive industry report analyzing quantum progress and its impact on blockchain security
- **Enterprise consulting & migration services**: Helping enterprises assess and transition to post-quantum cryptographic standards

## Market Standing
- **Valuation/Market Cap**: Not disclosed
- **Key Metric**: Total funding of **$26M** across two rounds
- **Notable Investors/Partners**: Investors: Castle Island Ventures (lead, Series A), Variant, Quantonation, and 11 total investors in Series A. Partners & collaborators: Ethereum Foundation, Ripple, Solana, Google, UC Berkeley, Stanford, Caltech, Chainalysis, Kraken (advisors)
- **Growth Signals**: 10 employees (+100% YoY); 2,729 LinkedIn followers; monthly website visits up 58.3% (18,208 visits); global audience including US (43%), Switzerland (19%), Nigeria (10%); recent collaborations with Ripple (XRP Ledger) and Solana; published paper accepted by International Association for Cryptologic Research; Q-Day Prize awarded (1 BTC)

## Competitive Advantages
- Deep technical expertise at the intersection of quantum computing and cryptography, with a dedicated applied research lab
- First-mover position in post-quantum migration for digital assets, producing open-source tooling (libqc, Quantum Vault) audited by the community
- Strong academic and industry partnerships (Stanford, Ethereum Foundation, Chainalysis, Kraken)
- Proven track record of real-world impact: Bitcoin Risq List used by leading institutions; regular publication of threat intelligence reports

## Strategic Focus
- Accelerating post-quantum readiness across major blockchain networks (Ethereum, Solana, Bitcoin, XRP Ledger)
- Advancing open-source cryptography standards and contributing to NIST’s post-quantum signature selection process
- Building enterprise-grade migration tooling and consulting services to help organizations transition before “Q-Day”
- Growing the team (10 employees) and expanding presence in the US and UK

## Why Work Here
- **Culture**: An applied lab of builders and technologists focused on solving one of the most critical security challenges of the coming decade. Emphasis on open-source contributions and cutting-edge research.
- **Work Environment**: Small, flat team (10 people) with a high degree of autonomy. Presence in US (New York) and UK. Likely remote/hybrid-friendly (team distributed across two countries).
- **Notable Perks**: Opportunity to work with world-class advisors (e.g., Dolev Bluvstein, Michael Gronager, Brian Mitchell), publish cryptographic research, and directly shape the post-quantum security landscape.
- **Engineering Culture**: Deep cryptography and blockchain engineering; contributions to open-source projects; collaboration with academic and industry leaders.

## Sources
1. [projecteleven.com](https://www.projecteleven.com/)
2. [Project Eleven Company Page](https://www.projecteleven.com/company)
3. [Careers Page (Ashby)](https://jobs.ashbyhq.com/projecteleven)
4. [About Us – Report Site](https://report.projecteleven.com/about-us)
5. [LinkedIn Company Page](https://www.linkedin.com/company/p-11)

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