Senior Payments API Engineer — Remote

Square; San Francisco (CA); Remote; USD 217,000 - 326,000; Full time

Benefits offered by this job

Remote work

Medical insurance

Flexible time off

Retirement savings plans

Job summary

Square, a leader in payment and financial services, seeks an experienced engineer to design and scale customer-facing payment APIs and related systems. You will lead large projects end-to-end, operate high-volume production environments, and improve system reliability and security.

The role emphasizes AI-assisted development and mentorship within a global engineering team. You will work across Block brands to deliver reusable payment capabilities, participate in on-call rotations, and help drive

Qualifications

• 8+ years of related experience with a Bachelor’s degree; or 6 years with a Master’s; or 3 years with a PhD.
• Experience building, maintaining, and scaling customer-facing financial or payment APIs.
• Experience designing and operating high-volume distributed systems with security and reliability in mind.
• Familiarity with idempotency, retries, async processing, and partial failure handling in payments.

Responsibilities

• Design, build, maintain, and scale customer-facing payment APIs with clear contracts and predictable behavior.
• Lead complex projects end to end from design through production, including testing and rollout.
• Operate critical payment systems serving worldwide traffic and participate in on-call rotations.
• Improve performance, observability, fault tolerance, and security; use automation to reduce repetitive work.
• Collaborate with product and engineering partners to turn requirements into reusable capabilities.
• Use AI-assisted tools for design, implementation, testing, and debugging, ensuring quality and safety.
• Shape technical decisions and mentor others through code reviews and documentation.

Skills

Payments APIs

Distributed systems

Incident response

AI-assisted tools

Code reviews

Mentoring

Communication

Education

Bachelor's degree or higher

PhD with 3 years experience

Tools

Kotlin

Go

TypeScript

AWS

Kafka

Job description

Square, a leader in payment and financial services, seeks an experienced engineer to design and scale customer-facing payment APIs and related systems. You will lead large projects end-to-end, operate high-volume production environments, and improve system reliability and security.

The role emphasizes AI-assisted development and mentorship within a global engineering team. You will work across Block brands to deliver reusable payment capabilities, participate in on-call rotations, and help drive