Staff Software Engineer, Partner Integrations

Flex

Join Flex as a Staff Software Engineer to design and maintain payment integrations, supporting our mission to improve rent payment experiences for users. Collaborate cross-functionally to deliver high-impact products and enhance our platform's performance.

Posted 6/9/2026full-timeRemote • California, New York • 🇺🇸 United StatesLead💰 $200,000 - $250,000 per yearWebsite

Tech Stack

Tools & technologies

AWSDistributed SystemsDynamoDBGradleJavaJUnitRuby on RailsSpring

About the role

Key responsibilities & impact

Design, implement, and maintain our payment integrations platform, including partner APIs, SDKs, and embedded web experiences
Help shape and drive the technical roadmap for the Partner Engineering team
Design and develop scalable APIs and integrations to support money movements across our banking partners via payment rails such as ACH
Work cross-functionally with Engineering, Product, Design, Infrastructure, Sales, Partner, and Customer Success to deliver high-impact features
Scale our integrations platform to support business growth while maintaining performance and reliability
Continuously improve daily operations through automation, tooling, design evolution, and observability
Mentor engineers and elevate team standards through best practices, code reviews, and technical guidance

Requirements

What you’ll need

Minimum 6 years of experience in software engineering
Minimum 4 years of experience with Java; proficient in Spring (core/web/boot), Gradle, JUnit, and JVM tuning
Experience with Service-Oriented Architecture, REST APIs, message queues, and scalable distributed systems
Experience with AWS (EKS, Aurora RDS, Elasticache, DynamoDB) and containerization
Experience leading delivery of multiple high-impact products end to end, on time with a high quality bar
Ability to work on a globally-distributed team with a high degree of ownership
Experience aligning technical and non-technical stakeholders on scope and delivery
Experience in FinTech and familiarity with major payment rails
Ability to drive quality and consistency across your team without compromising velocity.

Benefits

Comp & perks

Competitive medical, dental, and vision
Company equity
401(k) plan with company match
Unlimited paid time off + 13 company paid holidays
Parental leave
Free Flex subscription

ATS Keywords

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Hard Skills & Tools

JavaSpringGradleJUnitJVM tuningService-Oriented ArchitectureREST APIsmessage queuesscalable distributed systemsautomation

Soft Skills

mentoringtechnical guidancecross-functional collaborationownershipdelivery leadershipquality assurancecommunication