Fullstack Staff Engineer

DEUNA•San Francisco, CA

3d•Remote

About The Position

DEUNA is a rapidly growing startup revolutionizing global commerce with ATHIA, our AI-powered orchestration and payments platform that helps large enterprises boost approval rates, reduce costs, and unlock new revenue. Built by the team behind DEUNAâthe fastest-growing Commerce OS in Latin AmericaâATHIA combines payment intelligence, checkout optimization, and data orchestration in one powerful solution. With deep integrations across 300+ PSPs and alternative payment methods, and over 20% of Mexicoâs digital economy running through our platform, we simplify global payments through a single integration and centralized reconciliation. We are a rapidly growing startup expanding into the U.S. to meet the urgent needs of large retailers, marketplaces, airlines, and QSRs. Join us to shape the future of payments! ð Visit https://www.deuna.com/ to learn more about us! Role Overview We are looking for a Fullstack Staff Engineer to serve as a senior technical authority across our engineering organization. This role is designed for a highly experienced engineer who operates at a strategic level, shaping architecture, driving technical standards, and solving complex cross-domain problems. Unlike an Engineering Manager, this role is not focused on people management. Instead, you will act as a technical leader and architectural reference, influencing multiple teams and ensuring long-term scalability, reliability, and engineering excellence. You will thrive in a high-autonomy, fast-moving startup environment where technical decisions have direct product and business impact.

Requirements

Extensive experience as a Senior Engineer, Principal Engineer, or Staff Engineer in fullstack environments.
Strong frontend expertise in: React, Next.js and TypeScript
Strong backend experience with: Golang and/or Python
Deep experience designing distributed systems and scalable APIs.
Strong knowledge of: Data structures and algorithms Design patterns System design and architectural trade-offs
Experience with AWS and cloud-native architectures.
Experience with SQL and NoSQL databases.
Strong debugging, refactoring, and performance optimization skills.
Excellent written and verbal communication skills. Native or fluent English. Spanish is a plus.

Nice To Haves

Experience in payments, fintech, e-commerce, or transaction-heavy platforms.
Experience designing high-availability financial systems.
Exposure to compliance-sensitive or regulated environments.

Responsibilities

Define and evolve fullstack architecture across frontend and backend systems.
Lead complex system design initiatives, ensuring scalability, performance, and maintainability.
Establish and enforce engineering standards and best practices.
Drive technical alignment across teams.
Contribute directly to critical parts of the codebase.
Write scalable, production-ready, well-tested code.
Lead major refactors and performance optimizations.
Review code and provide deep technical guidance.
Partner with Product and Engineering leaders to evaluate trade-offs between scalability, security, cost, and speed.
Design APIs, database schemas, caching strategies, and distributed systems.
Guide teams in handling edge cases, failure scenarios, and observability.
Identify architectural bottlenecks and propose scalable improvements.
Evaluate new technologies and frameworks.
Improve system monitoring, instrumentation, and reliability practices.