Senior Full-Stack (TS/Nest/AI) Engineer

The Leap; Northern (KY); Hybrid; USD 140,000 - 200,000; Full time

Job summary

The Leap, a US-based fintech company building a live platform for escrow and trust accounting in real estate, seeks a Senior Full-Stack Engineer. You will own architecture, development, and deployments, shaping the product direction alongside the founder.

The role emphasizes TypeScript, NestJS, AI features, and production-grade financial logic. You’ll be joining as the first dedicated engineer, with high ownership and impact on the product’s evolution.

Qualifications

• 6+ years of professional software engineering experience with backend focus.
• Strong production experience with TypeScript and NestJS.
• Experience with Next.js or React.
• Strong PostgreSQL skills including writing and reviewing SQL.
• Hands-on ledger/financial logic experience (double-entry, reconciliation, postings).
• Experience shipping LLM/AI functionality to production (document extraction, structured outputs).
• AI-native development workflow tools like Cursor or Claude Code.
• CI/CD and AWS experience (ECS).
• Fintech, accounting, proptech, healthcare, or similar regulated environments.

Responsibilities

• Take ownership of a live production codebase and lead the transition from external development to in-house engineering.
• Review and strengthen the platform's accounting and ledger logic for correctness and auditability.
• Build new product functionality from AI-assisted prototypes created by the founder.
• Design and ship production AI features that process financial and real estate documents into structured data.
• Build safeguards around AI-generated data with traceability and human approval.
• Help scale the platform as transaction volume grows.
• Own deployments and production troubleshooting on AWS.
• Provide second- and third-tier technical support for critical issues.
• Collaborate with the founder and operations team and set practical engineering standards.
• Establish engineering quality standards as the company builds in-house tech.

Skills

TypeScript

NestJS

PostgreSQL

React

Next.js

AI/LLM integration

AWS

CI/CD

Ledger/FinTech

Tools

Next.js

React

AWS

ECS

SQL

Job description

About the job Senior Full-Stack (TS/Nest/AI) Engineer

Build AI-powered financial software with real ownership.

We're looking for a Senior Full-Stack Engineer to join a US-based fintech company building a live platform for escrow and trust accounting in real estate.

The product is already in production and handles financial transactions, accounting, documents, and client portals. The company is now bringing engineering in-house and is looking for its first dedicated engineer to take ownership of the technology and help shape the next stage of the product.

This is not a role where you'll own one small part of a large engineering organization. You'll have a direct impact on the architecture, product, and technical direction, working closely with the founder and having the freedom to make and defend your own technical decisions.

The role is backend-leaning full-stack, with a strong focus on TypeScript, AWS, financial logic, and production AI.

What You'll Work On:

• Take ownership of a live production codebase and lead the transition from an external development agency to an in-house engineering setup.
• Review and strengthen the platform's accounting and ledger logic, with a strong focus on correctness, reconciliation, auditability, and reliability.
• Build new product functionality from fast, AI-assisted prototypes created by the founder.
• Design and ship production AI features that process incoming financial and real-estate documents and turn unstructured information into structured data.
• Build safeguards around AI-generated data so that accuracy, traceability, and human approval are built into the workflow.
• Help scale the platform as transaction volume is expected to grow significantly.
• Own application deployments and production troubleshooting on AWS.
• Provide second- and third-tier technical support for critical technical issues.
• Work directly with the founder and operations team, bringing your own engineering judgment and challenging assumptions when needed.
• Establish practical engineering and quality standards as the company builds its in-house technical foundation.

What You Bring

Required:

• 6+ years of professional software engineering experience, with strong backend expertise.
• Strong production experience with TypeScript and NestJS.
• Experience with Next.js or React.
• Strong PostgreSQL skills, including writing and reviewing SQL directly.
• Hands‑on experience with ledger or financial logic - for example double-entry accounting, reconciliation, balances, payment posting, payouts, billing, or similar transaction-heavy systems.
• Experience shipping LLM/AI functionality to production, particularly document extraction, structured outputs, or similar use cases.
• A practical understanding of how to make AI systems reliable, traceable, scalable, and cost-efficient.
• An AI-native development workflow using tools such as Cursor, Claude Code, or similar.
• Experience with CI/CD and AWS, particularly ECS.
• Professional experience in fintech, accounting, proptech, healthcare, insurance, or another regulated environment.
• Ability to work 9 AM-5 PM in your local time and maintain regular working‑hour overlap with the US team.

Nice to Have:

• MongoDB
• Banking API integrations
• AWS Lambda and Step Functions
• Experience taking over and improving a codebase built by an external team
• Exposure to SOC 2 or similar compliance frameworks

Why Join?

• AI at the core: Build production AI features for a live financial platform rather than experimenting with AI as a side project.
• High ownership: You will be the main engineer responsible for architecture, development, and deployments.
• Direct impact: Work closely with the founder and have a direct influence on technical decisions.
• Interesting technical challenges: Make AI reliable enough for accounting and help scale a live product as transaction volume grows significantly.
• Predictable schedule: Normal 9-to-5 local working hours, with only rare emergency availability outside those hours.
• Growth opportunity: Join as the first in-house engineer while the company is preparing for significant product and business expansion.

If this sounds like a strong match for your experience, I'd be happy to tell you more about the opportunity and discuss the next steps.