[Contractor] Senior Blockchain Engineer (US based)

About Us Parity is one of the world’s most experienced companies building the core infrastructure behind blockchain — the system that allows information and value to be shared securely without needing an intermediary. We’re laying the foundation for a better web which respects the freedom and data of individuals, and empowers developers to build better, more trustworthy online services. Our remote-first, global team develops open-source software that anyone can use or improve. This includes Polkadot, Polkadot SDK, and Kusama — key parts of the Web3 tech stack, the next generation of the internet. Our mission is to make Polkadot the most active and innovative community in blockchain, powering a new era of connected and decentralised applications. About the Team This role sits in our Acceleration department, home to the people who drive ecosystem growth by building tools, integrations, and partnerships across the Polkadot network. Reporting into our Polkadot Research Lead, you’ll be joining the Polkadot Research Engineering team. We shape the Polkadot research vision and roadmap, translating ecosystem needs into tools and experiences that accelerate platform adoption. About the Role As a Senior Experience Engineer , you will lead the end-to-end delivery of features, from initial problem discovery to production deployment. This role is designed for a self-directed builder who prioritizes "what" to build as much as "how" to build it. You will leverage an AI-native workflow to iterate rapidly and deliver high-impact solutions to complex user problems. What you’ll do * Full-Lifecycle Ownership: Lead feature development through scoping, architecture, deployment, and iteration based on live user data. * AI-Augmented Development: Integrate AI tools (e.g., Cursor, Copilot, Claude) into your daily workflow to accelerate velocity and maximize output. * Autonomous Decision-Making: Navigate ambiguity by exercising sound judgment, filling requirement gaps without waiting for exhaustive specifications. * Rapid Iteration: Deploy MVPs quickly to gather real-world feedback, avoiding over-engineering in favor of momentum and validated learning. * Direct Collaboration: Partner with stakeholders and users to deeply understand pain points and translate them into functional, scalable software. * Cross-Functional Execution: Work proactively across the organization to remove blockers and maintain a high shipping cadence. Your Skills * Proven experience developing and maintaining production-grade web applications (ideally with TypeScript, React, or similar frameworks). * Strong understanding of frontend architecture, component-driven development, and modern build pipelines. * Possess a good understanding of system design and an ability to work with complex systems. * Strong product intuition for applying AI to solve real user problems and ship features that deliver genuine value. About Working With Us Joining Parity means joining team mates who are genuinely excited about the impact their projects are having, and the opportunity to grow alongside some of the brightest minds in the Web3 space! You’ll work remotely and flexibly, while still getting to meet your team mates throughout the year at team and company-wide retreats. Upon receiving an offer, all candidates undergo a background check through Zinc, our trusted third-party provider. Team members will be taken on as a contractor via our UK entity. View our Applicant Notice to see how we use your data. Parity is an Equal Opportunity Employer. We welcome diversity in our global team and care about everyone in our collective feeling included and welcome Is this position not quite your match? Browse our other open roles.

Since being founded in 2018, Copper has been building the standard for institutional digital asset infrastructure with a focus on custody, collateral management, and prime services. Led by Amar Kuchinad, Copper's Global CEO, the firm provides a comprehensive suite of custody, trading and settlement solutions that reduce counterparty risk and bring greater capital and operational efficiency to digital asset markets. At the heart of Copper's offering is Multi-Party Computation (MPC) technology – the gold standard in secure custody. Copper’s multi-award winning custody system is unique in that it can be connected to centralised exchanges, DeFi applications and even staking pools without the assets leaving the custody. Built on top of this state-of-the-art custody, ClearLoop is the first solution in the market that overcomes a growing industry challenge; counterparty risk with exchanges. This solution underpins a full prime services offering, connecting global exchanges, and enabling customers to trade and settle directly from the safety of their MPC-secured wallets. By reducing settlement time for transfers to a few milliseconds (without blockchain network dependency) and offering enhanced security measures, ClearLoop is rapidly reshaping the way asset managers trade and manage capital. In addition to industry-leading security certifications, Copper has one of the strongest insurance coverages in the industry from an A+ rated insurer, positioning the firm as the partner of choice for institutions seeking to safeguard their assets. Department/Team Purpose:  Copper provides institutional digital asset custody, settlement, and collateral management services across a wide range of blockchains and integrated venues. Information Security protects the firm's platforms, client assets, and regulated entities across the group. Role Purpose:  The Principal Security Architect is the senior technical authority for security architecture at Copper. The role reports to the CISO and partners closely with Engineering. The holder sets architectural direction, reviews and approves designs for major change, and acts as the firm's reference point on the security of the systems, protocols, and integrations Copper depends on. The role is predominantly architecture and assurance, with limited hands-on solution design in the cloud and integration space where reference patterns are needed. Key Responsibilities:   Architectural authority * Hold formal security sign-off authority for major changes to Copper's platforms, infrastructure, and integrations. * Shape and maintain the security architecture patterns, principles, and reference designs that engineering teams build against. * Provide the senior technical security position in architectural and business decisions, including escalations where security and delivery pressures conflict. Custody, signing, and cryptographic architecture  * Provide architectural security leadership over Copper's signing infrastructure, working alongside specialist engineering and cryptography teams. Scope covers the people, process, and operational design around MPC-based signing. Solid conceptual grounding in threshold cryptography and signature schemes is required; cryptographer-level work is not. * Review and approve changes to transaction construction, signing flows, approval policy, and key lifecycle operations. * Provide architectural assurance over chain-of-trust constructs adjacent to custody, including verifiable build pipelines, hardware-backed code signing, and authenticator-bound administrative paths. Multi-chain and integration security * Reason at architectural depth across the range of blockchains Copper supports, including EVM, UTXO, and account-based non-EVM families. This requires a working understanding of transaction construction, signing semantics, consensus assumptions, and validator and staking models across these environments, without being a protocol engineer in any of them. * Assess third-party smart contract architectures, implementations, and audit reports to a level sufficient to understand the exploit and risk surface, without performing line-by-line code review. * Review first-party integrations with partner networks, including those underpinning staking and similar on-chain participation, and form a defensible security position on the operational and contract risk Copper inherits. Settlement, collateral, and off-exchange architecture * Provide architectural ownership of the security model for Copper's settlement, collateral mirroring, and off-exchange product surfaces. * Reason about the trust boundaries between Copper, venues, and clients, and ensure architectural controls match the obligations each side carries. Identity and access architecture * Own identity and access architecture as a dedicated pillar of the role. * Set patterns for workforce, workload, and third-party identity across Entra ID, federated SSO, OAuth2 / OIDC, SAML, and modern authenticators. * Govern entitlement design, privileged access, and access models for contractors, vendors, and external operators. Cloud and platform security * Maintain working architectural fluency in both AWS and Azure, including network topology, segmentation, secrets handling, and platform telemetry. * Produce reference patterns and, where needed, direct integration designs in the cloud and platform space. Third-party and protocol risk * Lead technical security review of vendors, integrated venues, and protocols, including challenge of assurances that do not stand up to scrutiny. * Support client and counterparty due diligence on the technical content most likely to be misrepresented or under-specified. Policy, regulatory, and assurance support * Maintain a working understanding of the regulatory regimes applicable to Copper's licensed entities sufficient to translate architectural decisions into language Compliance and GRC can defend. Primary ownership of regulatory positioning sits elsewhere.  * Contribute to security policy, standards, and control framework development as the senior technical reviewer. * Participate in resilience exercises and incident reviews where architectural input materially shapes the outcome. Skills and Experience:  Essential   * Multi-chain architectural literacy. Able to reason across EVM, UTXO, and non-EVM account-based chains at the level of transaction construction, signing, consensus, and validator models. Comfortable assessing third-party smart contract designs, implementations, and audit reports for exploit and risk surface without performing code review. * Custody and signing architecture. Strong conceptual grasp of threshold signing, signature schemes, and key lifecycle. Able to design and challenge the operational architecture around signing, separation of duties, approval policy, key ceremony equivalents in MPC, and recovery, to a high standard. * Settlement and collateral architecture. Demonstrable experience reasoning about settlement, collateral, and off-exchange constructs, including trust boundaries between custodians, venues, and clients. * Identity and access architecture. Senior-level experience designing and governing identity across Entra ID, federated SSO, OAuth2 / OIDC, SAML, and modern authenticators. Comfortable with entitlement governance and third-party access design. * Cloud security. Working architectural understanding of AWS and Azure, including the ability to produce reference patterns and limited direct integration designs. * Architectural authority and judgement. Track record of holding sign-off on significant designs, taking defensible positions under uncertainty, and owning residual risk. * Change review and assurance. Comfortable reviewing the work of engineering peers, infrastructure changes, and vendor designs, and able to hold the line where it matters. * Communication. Able to operate credibly with engineers, senior business stakeholders, auditors, and regulators in the same week, without losing precision at any of them. Desirable   * Familiarity with chain-of-trust constructs including verifiable builds, reproducible build pipelines, and hardware-backed code signing. * Awareness of the regulatory landscape relevant to digital asset custody and trading (for example FCA, FINMA, FSRA / ADGM, MiCA). * Compliance familiarity across ISO 27001, SOC 2, and NIST CSF / 800-53, with the ability to map controls cleanly between them. * Enterprise architecture grounding (TOGAF, SABSA) where it complements rather than replaces technical depth. Why Copper?   At Copper, we keep innovation, openness, and curiosity at the centre of everything we do. Here, bold ideas get the spotlight, learning is constant, and diversity shapes our team from the ground up. Jump into a fast-moving, dynamic team that loves a challenge and knows how to have fun along the way. Collaboration is just as important as results—you’ll be surrounded by smart, driven colleagues in London and across our APAC, Switzerland, UAE, and US offices. Hybrid working model – we believe in the value of bringing people together and at the same time we embrace the adaptability of flexibly working. Diversity and inclusion matter to us – they’re woven into Copper life. From employee-led groups like Women at Copper to a committee focused on community and wellbeing, you’ll have a network that supports you from day one. Everyone voice matters. If you’re looking to ramp up your career, or keen to do something new in your field, with us, you’ll keep moving forward. Ready to make your mark, keep growing, and join a supportive, dynamic team? Copper’s the place. The interview process at Copper   Our interview process is designed to be thoughtful, efficient, and engaging. While specific steps may vary slightly depending on the role, the typical journey includes: 1. Initial Screening A brief conversation with our Talent Acquisition team to explore your background, motivations, and alignment with the role. 2. Technical Interview A virtual session conducted via Microsoft Teams, where you'll engage with team members to discuss relevant skills, problem-solving approaches, and technical experience. 3. In-Person Interview A conversation focused on team dynamics, collaboration style, and any final technical questions. This may be with cross-functional peers or leadership. Additional steps may be added based on the role's complexity or seniority. We aim to keep the process transparent and respectful of your time. Benefits  In return for everything you can bring to Copper, we can offer you an exciting, challenging role in a fast-growing and dynamic business, with career opportunities and welcoming working environment. Some of our key UK benefits are highlighted below:  * Paid Time Off - A minimum of 35 days of paid time off per year, inclusive of annual leave and public holidays. Employees also receive one additional day of annual leave for each year of service. * Comprehensive Medical Insurance - Inclusive of dental, optical, audiology, and mental health coverage, with medical history disregarded * Life Insurance * Enhanced Pension Contributions - Includes an enhanced employer matching contribution * 24/7 Employee Assistance Programme (EAP) If you think you have everything we're looking for and more, then we'd love you to apply for the opportunity.  Copper is an equal opportunity employer. We embrace diversity and equal opportunities in a serious way. We are committed to building a team that represents a variety of backgrounds, perspectives, and skills. The more inclusive we are, the better our work will be. So, bring us your experience, perspectives, and skills. It is in our differences that we will continue to grow and ensure Copper is transforming how institutional investors engage with digital assets. Copper is a Disability Confident Employer, please let us know if you have a disability. If you require us to provide any assistance during the recruitment process, then we would ask you to highlight this to us and we will be happy to accommodate.