Software Development Engineer (AWS), Core Platform

About Tennum Tennum is an AI-powered property management system that handles tenant communications, maintenance coordination, and operational workflows for self-managing landlords. We're a two-person founding team preparing to launch a pilot with our first group of landlords in the next 8–10 weeks. We have a fully designed backend architecture (detailed DynamoDB schemas, API contracts, sequence diagrams, and write semantics for every subsystem) and we need a strong engineer to implement it. The Role You'll be building production backend services from detailed architecture specs. The CTO has written comprehensive design docs for each subsystem. Your job is to implement these faithfully, quickly, and cleanly. This is not a greenfield design role. You won't be making architectural decisions. You'll be translating precise specs into working code, asking smart questions when something is ambiguous, and shipping fast. What You'll Build • Core CRUD APIs with concurrency and transaction requirements (Lambda + API Gateway) authenticated with Cognito and IAM. • Serverless event handlers in distributed systems, including DynamoDB Streams consumers for message routing, task orchestration, and state reconciliation. • User authentication system (Cognito user pool, post-confirmation triggers, JWT authorizer, reconciler). • Document upload and extraction flows with presigned S3 URLs, versioned object storage, and LLM-backed structured data extraction. • Public website and web console for authenticated customers. • Alarms and dashboards (via CloudWatch). Requirements Basic Qualifications • 3+ years of professional software development experience. • Knowledge of TypeScript and Functional Programming. • Experience with React and Web Development. • Experience with AWS serverless technologies (Lambda, DynamoDB, API Gateway, S3, Cognito, IAM). • Experience with DynamoDB data modeling — GSI design, conditional expressions, TransactWriteItems, and optimistic concurrency. • Experience with DynamoDB Streams and event-driven architectures. • Experience with S3 (presigned URLs, versioned objects, lifecycle policies). • Experience with Infrastructure-as-Code (AWS CDK). • Strong English communication (you'll send daily async updates and ask clarifying questions proactively). • Comfortable working a shifted schedule: approximately noon–8 PM your local time (overlap with US East Coast evenings required). Preferred Qualifications • Knowledge of Effect-TS. • Experience with design and implementation of Cloud Native software systems. • Experience with CI/CD pipelines. • Experience integrating LLM APIs (structured output, schema validation, error handling). • Experience with Cognito user pools, hosted UI, and post-confirmation Lambda triggers. How We Work • You'll receive detailed architecture docs for each subsystem before you start building. • The CTO reviews all code — expect direct feedback. • Daily async updates: what you finished, what you're starting, any blockers. • Calls when needed with the CTO for code review, questions, and alignment, usually during US Eastern evening. • We move fast and ship continuously. Schedule & Compensation • Ongoing contract, full-time hours (approximately 40 hrs/week). • $30–35/hour USD depending on experience. • Working hours: approximately noon–8 PM your local time (flexible within reason, but evening US overlap is required). How to Apply Tell us: A current resume or CV. Your experience with AWS serverless and DynamoDB specifically What AI coding tools you use and how they fit into your workflow, be specific. Your availability to start. Paid trial task: Qualified candidates will receive a detailed architecture doc for one of our subsystems and 48 hours to implement it. We pay $125 for the trial regardless of outcome. This is how we evaluate fit