Senior Software Engineer I

MX Technologies, Inc. • Lehi, UT

1d

About The Position

MX is a financial technology company that builds data infrastructure and intelligent solutions for banks, credit unions, and fintechs. The Senior Software Engineer I role is on the Experiences team, which develops personal financial management products, including a money management dashboard, embeddable budgeting, spending, and cash-flow widgets, and a personalized insights feed for financial institutions’ digital banking apps.

This is a full-stack role for an engineer experienced with React and TypeScript on the front end and backend services, with applied AI experience. The engineer will deliver features across React widgets, a shared TypeScript widget library, and the APIs and services that power them. They will also build and operate LLM-powered features that help people understand financial data, applying privacy and security safeguards for sensitive information.

The team is modernizing its platform, including moving the dashboard’s data layer from a legacy Ruby on Rails API to a TypeScript API service and updating older front ends to the current React, TypeScript, and design-system stack. The role includes project ownership from design through implementation, testing, deployment, maintenance, and production support, as well as technical leadership, collaboration with product partners, and support for teammates’ growth.

Requirements

• Bachelor’s degree or equivalent experience.
• At least 5 years of software development experience in one or more programming languages.
• At least 3 years of experience testing, maintaining, or launching software products.
• Professional full-stack experience, including production React with TypeScript and building and operating backend services or APIs in at least one server-side language, such as Ruby on Rails or TypeScript on Node.js.
• Experience designing and consuming APIs (REST, RPC, or message-based) and working with caching, background jobs, and asynchronous or event-driven systems.
• Hands-on experience shipping at least one feature or internal tool built on a large language model API.

Nice To Haves

• Experience with retrieval-augmented generation, agent or tool-use architectures, or protocols for exposing tools and data to models, such as MCP.
• Experience building LLM evaluation harnesses, prompt regression suites, or guardrail layers, and monitoring LLM cost, latency, and quality in production.
• Experience with managed model platforms on a major cloud provider, such as Vertex AI, Bedrock, or Azure OpenAI.
• Experience with front-end technologies including React 18/19, MobX or Redux, Material UI, Vite, Vitest, Playwright, Storybook, and shared component libraries or design systems.
• Experience with backend technologies including Ruby on Rails (including JRuby) with Sidekiq, TypeScript services on Bun or Node.js (such as Hono), Elixir/Phoenix, PostgreSQL, Redis, NATS or RabbitMQ, and protobuf-based RPC.
• Experience with Kubernetes, Docker, CI/CD pipelines, and observability tools such as Datadog or OpenTelemetry.
• Fintech, banking, or other regulated-data domain experience.

Responsibilities

• Write product or system development code.
• Participate in or lead design reviews with peers and stakeholders to choose among available technologies.
• Review other developers’ code and provide feedback on style, accuracy, testability, and efficiency.
• Promote clean code and strong engineering practices through thoughtful code reviews.
• Help build and maintain MX’s technology systems in support of its mission.
• Collaborate with Product Managers to meet customer needs simply and effectively.
• Contribute to documentation and educational content, adapting it to product updates and user feedback.
• Triage and resolve product or system issues by analyzing their sources and impact on hardware, networks, services, and quality.
• Participate in architecture discussions and technical design reviews to support scalability, reliability, and security.
• Elevate design, implementation quality, and engineering practices across the team.
• Drive projects and initiatives to deliver high-quality systems and products.
• Influence, coach, and support engineers, with a focus on feedback and growth.
• Deliver end-to-end features across embeddable React widgets, the shared TypeScript widget library, and backend APIs and services.
• Contribute to platform modernization by moving the dashboard data layer from a legacy Ruby on Rails API to a TypeScript API service and migrating older front ends to the current React, TypeScript, and design-system stack.
• Design, build, and operate LLM-powered product features, including prompt and context design, retrieval, tool calling, evaluation, and production monitoring.
• Apply privacy and security safeguards to LLM use with financial data, including data minimization, PII redaction, access scoping, output validation, and audit logging, in partnership with Security and Compliance.
• Balance model quality, latency, and cost, and determine when an LLM is appropriate versus a deterministic solution.
• Use and improve AI-assisted development workflows, help teammates adopt them, and verify AI-generated output.
• Build and maintain automated unit, integration, contract, and end-to-end tests, along with observability for customer-facing services.
• Estimate engineering efforts; design, implement, test, deploy, maintain, and enhance software solutions.
• Manage project priorities, deadlines, and deliverables.

What This Job Offers

• Job Type: Full-time
• Career Level: Senior