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.

About the Role

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.

What you’ll do

• 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.

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.

##### 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.

Nice-to-have (but not required)

• 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

We look beyond specific skills to find people who are thoughtful builders, clear communicators, and passionate collaborators. We value pragmatic idealism and curiosity. If you’ve wrestled with complex systems, navigated ambiguity gracefully, and thoughtfully made trade-offs, you’ll fit right in.

##### 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.

At Gnosis, we strive to create an inclusive environment that empowers our employees. We believe that our products and services benefit from our diverse backgrounds and experiences and are proud to be an equal opportunity employer: all qualified applicants are considered for positions regardless of race, ethnic origin, age, religion or belief, marital status, gender identification, sexual orientation, or physical ability.