Senior Full Stack Engineer

Spectrum Search; United States; Remote; USD 120,000 - 180,000; Full time

Job summary

Spectrum Search is looking for a product-focused engineer to own customer-facing systems across backend, frontend and AI-enabled capabilities. The role is backend-leaning but truly full stack, with end-to-end ownership from product definition to production.

You will build and evolve systems for payment processing, financial workflows, integrations and AI-powered features, working across application logic, databases and React-based UIs with a collaborative team.

Qualifications

• Backend-leaning full-stack experience with production ownership.
• Experience with MVC frameworks such as Rails, Django or Spring Boot.
• Advanced experience with PostgreSQL or SQL databases.
• Ability to own features from conception through delivery and measurement.
• Experience using AI-assisted development tooling in daily work.
• Comfort working in rapid iteration with strong individual ownership.

Responsibilities

• Design, build and operate production-grade payment and financial workflow systems.
• Develop secure APIs and integrations with enterprise platforms.
• Build full-stack features across backend services, PostgreSQL and React.
• Develop LLM-powered workflows and agentic AI features for complex processes.
• Create evaluation frameworks, observability and guardrails for AI in production.
• Build and maintain data pipelines processing high volumes of financial records.
• Own features from initial customer requirements through delivery and measurement.
• Contribute to system architecture, technical conventions, code reviews and quality.

Skills

Full-stack

MVC frameworks

PostgreSQL

End-to-end ownership

AI tooling

Tools

Ruby on Rails

Django

Spring Boot

React

AWS

Terraform

Job description

Spectrum Search is partnered with an early-stage AI-enabled financial technology company building software for complex B2B payment and revenue workflows. The company is looking for a product-focused engineer to take end-to-end ownership of customer-facing systems across backend, frontend and AI-enabled functionality.

About the opportunity

This is a full-time engineering role within a small, highly collaborative product team. Engineers work directly across product definition, architecture, implementation, testing and measurement, with significant ownership over what reaches production.

The environment is highly iterative and AI-enabled. The team uses modern AI development tooling as part of its day-to-day engineering workflow, while engineers remain responsible for technical decisions, system quality and production outcomes.

The role

You will build and evolve systems supporting payment processing, financial workflows, integrations and AI-powered product capabilities. The role is backend-leaning but genuinely full stack, requiring engineers who are comfortable moving between application logic, databases, APIs and React-based user experiences.

You will also work directly with customer signals and feedback, helping translate real operational problems into well-scoped technical solutions.

Key responsibilities

• Design, build and operate production-grade payment and financial workflow systems
• Develop secure APIs and integrations with third-party enterprise platforms
• Build full-stack product features across backend services, PostgreSQL and React
• Develop LLM-powered workflows and agentic AI features for complex operational processes
• Create evaluation frameworks, observability and guardrails for AI functionality in production
• Build and maintain data pipelines processing high volumes of financial records
• Own features from initial customer requirements through specification, delivery and measurement
• Contribute to system architecture, technical conventions, code reviews and engineering quality

Essential requirements

• Proven experience as a backend-leaning full-stack software engineer, with strong recent ownership of production systems and user-facing features
• Strong backend expertise using an MVC framework such as Ruby on Rails, Django or Spring Boot
• Advanced experience with SQL databases such as PostgreSQL
• Ability to deliver across backend, frontend, database schema and automated testing without relying on functional hand-offs
• Experience working in an environment with rapid product iteration and meaningful individual ownership
• Strong product engineering mindset with experience taking responsibility beyond initial feature launch
• Comfortable engaging with users and customer feedback to inform technical decisions
• Active use of AI-assisted development tooling in day-to-day engineering workflows
• Strong ability to decompose product requirements into clear, scoped engineering work

Nice-to-haves

• Experience shipping production-grade agentic AI or LLM features
• Experience with AI evaluation systems, A/B testing or multi-arm bandit approaches
• Product engineering experience within fintech, payments or billing
• Experience with Ruby on Rails, React, AWS or Terraform

Location and remote setup

This is a full-time, remote position for candidates based in the US. Quarterly in-person off-sites are required. Visa sponsorship is not available for this position.