Senior Backend Developer

what you will do

About Circles

Circles is a radically different kind of money—issued directly by people, secured cryptographically, and powered by a decentralized web of trust. It’s money as a public good: open, transparent, and fair by design.

Instead of banks or gatekeepers, every user creates their personal money in the form of a Token. Trust connections between users weave these individual currencies into a spendable whole. Our vision is money that belongs to people, strengthens communities, and feels natural, intuitive, and fair.

We’re a diverse team united by curiosity, idealism, and pragmatism. We build carefully, openly, and always with the community in mind. Everything we make is open-source from day one.

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.

• Blockchain Data Indexing
  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.

• API & Developer Infrastructure
  Develop robust APIs (JSON-RPC/HTTP) that enable wallets, community apps, explorers, and analytics dashboards to reliably query Circles data in real-time.

• Web-of-Trust & Pathfinding
  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.

• Off-chain Data Handling
  Manage reliable off-chain storage of user profiles, group information, and metadata (IPFS-backed). Ensure efficient storage, fast retrieval, and secure updates.

• Developer SDKs
  Create and maintain intuitive, strongly-typed backend SDKs to support community developers building apps and integrations on Circles.

• Reliability & Security
  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.

• Open Collaboration & Documentation
  Write clear documentation, share knowledge openly, and actively welcome contributions from our community. Your code and documentation will be public and built for transparency.

• 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.

who you are

• 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.

• Experience with IPFS or decentralized storage.

• Experience with community driven projects.

• Familiarity with algorithms and graph theory.

• Interest in tokenomics, decentralization, or community-driven economics.

What we value

what we can offer you

• Personal Development: Pursue your professional goals with our support, including personal education budgets and conference allowances. We invest in your growth and learning.
• Innovation and Experimentation: Interested in exploring new ideas? Dedicate your Friday afternoons to research or work on a side project within our ecosystem. We encourage creativity and experimentation.
• Flat Hierarchy: Navigate with ease in our organization. Our flat hierarchy ensures your ideas and contributions are valued and heard, without getting lost in a complex structure.
• Flexible and Remote Work: Not a morning person? No problem! We embrace flexible working schedules and have a long-standing culture of remote work. Balance your professional and personal life in a way that works for you.
• State-of-the-Art Equipment: Receive the latest hardware and all the tools you need. We make sure you're well-equipped to do your best work.
• Growth and Opportunity: Grow with us in an exciting industry. As Gnosis rapidly expands, so do the opportunities for you to make a significant impact. We value initiative and a proactive approach.
• Community and Mission: Join a team that's passionate about our mission and enjoys working together. We’re not just colleagues; we’re a community driven by a shared goal.