Senior Backend Developer, Gnosis

• You have several years (5+) experience building and operating production-grade backend systems
• You’re strong in TypeScript (Node.js) and comfortable diving into C#/.NET or willing to quickly learn it
• You have practical experience with SQL (PostgreSQL) and understand how to optimize database performance
• You’ve previously worked with blockchain indexing, Ethereum JSON-RPC, event-driven systems, or similarly complex backend architectures
• You build APIs with empathy for the developers who will use them—designing interfaces that feel natural and easy to reason about
• You thrive in remote, autonomous teams, taking ownership from design through deployment
• You genuinely care about open-source software and public-good infrastructure

Desirable

• We're looking for a senior backend developer to design and build the infrastructure that makes Circles a trustworthy payment method in everyday life
• You'll build systems to capture and index blockchain events, create accessible APIs for developers, manage off-chain user data (profiles, trust relationships, group metadata), and ensure the whole system stays reliable—even when the network behaves unpredictably
• Our stack is rooted primarily in TypeScript, C#, SQL, and occasionally Python and Rust, but we choose technologies based on their merits, not just habits. You’ll be collaborating closely with our smart-contract developers, frontend engineers, community contributors, and designers
• Build, maintain, and evolve our custom Circles blockchain indexer (Nethermind plugin, C#/.NET) which ingests and organizes events into PostgreSQL. Ensure it stays consistent even through network disruptions, reorganizations, and edge-cases
• Develop robust APIs (JSON-RPC/HTTP) that enable wallets, community apps, explorers, and analytics dashboards to reliably query Circles data in real-time
• Extend and tune our pathfinding service to determine viable token-transfer routes through trust connections. Make complex graph computations accessible via clean APIs to power seamless payments and insights
• Manage reliable off-chain storage of user profiles, group information, and metadata (IPFS-backed). Ensure efficient storage, fast retrieval, and secure updates
• Create and maintain intuitive, strongly-typed backend SDKs to support community developers building apps and integrations on Circles
• Design robust services that gracefully handle failures, spikes in traffic, and other real-world scenarios. Implement observability through metrics, logs, and alerts. Ensure sensitive keys and operations remain secure
• Write clear documentation, share knowledge openly, and actively welcome contributions from our community. Your code and documentation will be public and built for transparency
• Initial projects you'll dive into
• Circles Nethermind Indexer:
• Ensuring reliable, real-time indexing of blockchain events into PostgreSQL
• Pathfinder Service:
• Improving the pathfinder service that computes viable transaction paths through the trust network
• Profiles Backend:
• Building efficient, secure storage and retrieval mechanisms for off-chain user data (profiles, images, metadata)
• Server-side SDKs:
• Creating easy-to-use SDKs that enable third-party developers to quickly integrate Circles into their own applications