Location : London (or remote) 3-6 month freelance contract Our client is a technology company that builds decentralized digital identity solutions. They believe that everyone has the right to own and control their data, and they are committed to creating a trusted digital credentials ecosystem that empowers businesses and individuals to securely exchange data and services across borders and industries. They are in search of a solution-oriented Rust Software Engineer (Backend) with deep, demonstrable expertise and experience in Rust, to work on secure, scalable, and high-performance backend systems. You will be responsible for the continued enhancement and development of a multi-component platform, where your expert skills in designing, architecting, and building quality systems will intersect with your hands-on coding, performance testing, and integration experience. Responsibilities: Build and deliver secure, high-quality features and improvements using Rust. Experience in TypeScript and Dart will set you above other applicants for this role Create standards-compliant world-class software systems and components, most of which will be open-sourced. Influence architectural direction while staying hands-on with development Design and implement solutions to c omplex, large-scale technical challenges Identify and drive the most critical improvements in product quality, security, and performance Guide the team to build well-tested, secure, and performant services Establish and refine best practices for high-scale distributed systems Collaborate closely with product, security, and engineering peers in a fast-paced, iterative environment Requirements: Proven experience with performance optimization and a track record of diagnosing and preventing system bottlenecks Strong backend development skills with Rust as a core expertise Deep knowledge of TypeScript/Node.js; Dart experience strongly preferred. Familiarity with C# or Go is a plus Expertise in cloud computing (AWS) and cloud-native environments Proven track record in designing and deploying distributed systems using modern design patterns Skilled in technical documentation (C4 Model, ADRs) and clear communication of architectural decisions Strong advocate for privacy by design, security-first principles, and high-performance systems Expertise in applying asymmetric cryptography in production-grade products Experience with authorization/authentication domains; knowledge of identity, verifiable credentials, or secure data exchange is a strong plus Comfortable thriving in autonomous, fast-moving startup environments and collaborating across global teams