Freelance Remote Full Stack Web Developer Jobs in Missouri

Remote Europe / Latam Full Time Individual Contributor +5 Years of Experience

Senior Web Developer Who We Are

Yuno is the AI-native operating system of global commerce, powering the financial infrastructure of enterprise merchants, banks, and wallets. Through a single API, Yuno connects them to pay-ins, payouts, fraud prevention, KYC/KYB, and stablecoins globally, so they can operate everywhere. Agnostic by design and connected to 1,000+ payment methods and 460+ integrations in 190+ countries, Yuno optimizes acceptance rates, reduces costs, and strengthens security through specialized AI agents that learn from every transaction. Global brands including McDonald's, NetEase Games, GoFundMe, and Rappi run their payments on Yuno.

About The Role

Yuno is looking for a Senior Web Developer to build the SDK, design system, and web components that power how third parties integrate with our platform. You'll own the developer-facing surface of Yuno's single API - the reusable components and SDKs that merchants, banks, and partners embed into their own products across browsers, frameworks, and environments.

This is a role where developer experience is the product: the quality, performance, and consistency of what you ship directly shape how easily the world connects to Yuno.

How AI Shows Up in This Role

• AI is our default execution layer - you'll use AI-assisted tools like Claude Code, Cursor, and GitHub Copilot, and LLMs more broadly, across design, implementation, debugging, testing, documentation, and code review as standard practice, not novelty
• You'll help shape how the engineering team works with AI, building workflows with AI agents and MCP servers and defining AI-driven development practices that raise the whole team's leverage
• The SDKs and components you build are the developer-facing edge of an AI-native payments platform whose agents learn from every transaction on the network

Your Contribution Will Be

• SDK and design system - create the design system and web components used across third-party applications, ensuring SDK compatibility across browsers, frameworks, and integration environments
• Cross-platform consistency - collaborate with backend and mobile teams so the SDK behaves consistently across every platform and integration
• Performance and build optimization - design low-latency, high-availability applications and optimize bundle size, tree-shaking, and build performance for SDK distribution
• Full-stack integration - connect user-facing elements with server-side logic and integrate data storage solutions into cohesive, reliable systems
• Code quality and security - write reusable, testable, and efficient code, and implement security and data protection throughout
• Developer experience and releases - maintain high-quality documentation and DX for integrators, and design automated pipelines for publishing and versioning SDK releases

What Success Looks Like

Within your first 6-12 months, you've shipped SDK components adopted by external integrators, raised the bar on developer experience and documentation, and own the pipeline that publishes and versions Yuno's web SDKs.

Skills You Need Minimum Qualifications

• 5+ years building production applications with React, with strong JavaScript and TypeScript
• Solid command of the modern web stack - Node, CSS, Next.js, Storybook, and Emotion
• Engineering fundamentals - OOP, Git, unit and E2E testing, and CI/CD
• Build and packaging tooling (NPM / yarn), with an eye for bundle size and performance
• AWS (S3, Amplify) and Docker
• AI-assisted development - fluent use of tools like Claude Code, Cursor, or GitHub Copilot, and leveraging LLMs across design, implementation, debugging, testing, documentation, and code reviews
• Autonomy and agile delivery - you own tasks end to end and work comfortably in SCRUM
• English - advanced proficiency, written and spoken

Preferred Qualifications

• Experience in the payments industry and integrating Payment Service Providers (PSPs)
• Backend experience (e.g., NestJS) and familiarity with backend languages
• Building custom workflows with AI agents, MCP servers, development assistants, or engineering automation platforms

Nice to Have

• Experience defining AI-driven development practices within an engineering team
• Spanish proficiency

What We Offer at Yuno

• Competitive Compensation
• Remote Work - you can work from everywhere
• Home Office Bonus - a one-time allowance to set up your ideal home office
• Work Equipment
• Stock Options
• Health Plan wherever you are
• Flexible Days Off
• Language, Professional, and Personal Growth courses

We may use artificial intelligence (AI) tools to support parts of the hiring process, such as reviewing applications, analyzing resumes, or assessing responses. These tools assist our recruitment team but do not replace human judgment. Final hiring decisions are ultimately made by humans. If you would like more information about how your data is processed or wish to exercise your data protection rights, please contact us at [email protected].