Backend Engineer
Senior Backend Engineer at deCircle building AI‑powered, security‑centric infrastructure for DeFi and data services, focusing on low‑latency request processing, trust‑minimized micropayments, and production‑grade distributed systems using Python, Go, GraphQL, and AWS.
Semiotic Labs is a venture studio building ambitious products at the intersection of AI, security, data, and infrastructure. Past ventures include Odos , a leading liquidity aggregator, and Cambrian , which provides low-latency, high-quality DeFi data for financial agents.
We were also core developers of The Graph protocol and have worked on problems including trust-minimized micropayments , low-latency request processing , data verification , and dynamic pricing . Our team has published research at venues such as NeurIPS and built novel optimization systems and production-grade distributed software.
Our latest ventures include:
Agentium Studio : a multi-tenant Saas platform for AI-powered financial workflows that operates on confidential documents under SOC 2 controls, accelerating multi-party collaboration for workflows like M&A, diligence, and consulting engagements.
AgentVisor : a sandboxing layer for agents with security and observability built in.
Agentium OS : an enterprise platform for agent safety, control, and observability.
About the role
We’re hiring a Senior Backend Engineer to help build Agentium Studio. You’ll design and ship the backend systems behind core product workflows, APIs, integrations, and parts of the agent runtime layer. This is a high-ownership role for someone who enjoys moving between product engineering and systems design. You should be comfortable turning ambiguous requirements into clear technical plans, shipping production code, and raising the bar for reliability, simplicity, and maintainability.
You’ll work closely with engineers, researchers, and product stakeholders on problems at the frontier of AI applications, security, and enterprise software.
Tech stack
Python 3.12+, FastAPI, Pydantic 2, async SQLAlchemy 2.0
PostgreSQL 16 with pgvector and row-level security for tenant isolation
Redis, OpenTelemetry, AWS
React 19 + Vite frontend; backend engineers should be comfortable reading frontend code during integration work
What you’ll do
Design, build, and maintain scalable async backend services and APIs in Python.
Own core systems end-to-end: architecture, implementation, testing, deployment, and operational excellence.
Build systems for multi-tenant workflows, fine-grained permissions, integrations, and agent-driven product experiences.
Write and review database migrations and row-level security policies in a compliance-sensitive environment.
Improve reliability, observability, and performance across critical paths.
Collaborate closely with product, design, and research to translate user needs into robust backend architecture.
Contribute to engineering standards, code review culture, and team ways of working.
Help shape technical direction in a fast-moving environment with evolving product requirements.
Why join
Posted June 19, 2026