Senior Software Engineer (Full Stack)

Castellum.AI•New York, NY

18h•$160,000 - $200,000•Remote

About The Position

Castellum.AI is hiring a Senior Software Engineer to help build its AI agents and screening platform for AML/KYC compliance. The engineer will join a growing team and own projects end to end across data pipelines, the Go API layer, AI agents, and the customer-facing platform. This is a high-agency role involving ambiguous problems, technical decision-making, and shipping reliable software. The work is primarily hands-on engineering, including feature development and bug fixes from architecture decisions through delivery. Engineers use AI/LLM tools as a productivity aid while evaluating tradeoffs and quality-checking their own changes. The team shares a one-week on-call rotation, mostly during Eastern Time business hours. A dedicated DevOps engineer handles major infrastructure work. The stack includes Go, gRPC, and protobufs for APIs; Python for agents, ETL, and data pipelines; TypeScript and React for the frontend; and PostgreSQL and Elasticsearch for data. The role is fully remote within the United States, with Eastern working hours. The company describes typical weeks as approximately 45–50 hours, with flexibility when personal circumstances require it.

Requirements

At least 5 years of professional experience building web applications, APIs, and back-end systems.
Experience with Python or Go.
Strong TypeScript experience; candidates are expected to ramp up on the listed language they know least.
Experience with PostgreSQL or a similar relational database technology.
Clear written and verbal communication skills.
Experience getting practical value from AI developer tools.
Prior experience at a startup or on a small, fast-moving team.

Nice To Haves

Experience with Elasticsearch, gRPC, or protobufs.
Experience building AI agents.
Experience with containerization and distributed systems.

Responsibilities

Own engineering projects end to end, including deciding scope and making implementation tradeoffs.
Build and maintain data pipelines, the Go API layer, AI agents, and the customer-facing platform.
Develop web applications, APIs, and back-end systems, including feature work and bug fixes.
Make architecture decisions, break work into manageable pieces, and implement the resulting solutions.
Use AI/LLM developer tools effectively while reviewing their output, making sound tradeoffs, and quality-checking changes.
Communicate engineering decisions and customer requirements clearly, and provide constructive pushback when appropriate.
Participate in a shared one-week on-call rotation, mostly during Eastern Time business hours.