Semiotic Labs - Senior Backend Engineer

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

• Work on technically challenging products at the intersection of AI, security, and enterprise software.
• Join a small, senior team with deep experience in research, distributed systems, and production engineering.
• Have meaningful influence over architecture, product direction, and engineering culture.
• Build products with real-world impact, not just prototypes

Do you have experience in TypeScript?, * 5+ years of professional software engineering experience with substantial backend development experience.

• Strong production experience building backend services in Python.
• Strong experience with asynchronous programming in Python, such as asyncio, async database access, or high-concurrency service development.
• Deep PostgreSQL experience, including schema design, query tuning, transactions, and production migrations.
• Experience designing or implementing multi-tenant data isolation and access control.
• Strong software design fundamentals: modular architecture, testing discipline, maintainability, and clear interface design.
• Experience with Redis or similar infrastructure for caching, queues, rate limiting, or pub/sub.
• Ability to independently own projects and make sound technical tradeoffs in ambiguous environments.
• Strong communication skills and a collaborative, low-ego working style., * Experience with FastAPI, Starlette, Litestar, or another modern Python web framework.
• Experience building backend systems for AI products, agentic workflows, or LLM-powered applications, such as RAG pipelines, tool-calling agents, or orchestration layers.
• Experience with security-sensitive or enterprise systems, including access controls, audit logging, and compliance-driven engineering constraints.
• Experience with OpenTelemetry or comparable production observability tooling., * Experience with pgvector, SurrealDB, or other vector retrieval systems.
• Exposure to SOC 2, fintech, healthtech, or other regulated environments.
• Experience with agent runtimes, sandboxing, or MCP integrations.
• Familiarity with distributed systems, asynchronous processing, and performance optimization.
• Startup or zero-to-one experience.
• Comfort reading TypeScript or React during frontend-backend integration work., * You have strong engineering judgment and care about systems that are simple, reliable, and useful.
• You thrive in small, high-trust teams where autonomy comes with real ownership.
• You enjoy hard problems but stay grounded in user value and practical execution.
• You bring a growth mindset, high standards, and a willingness to learn across disciplines.

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.