Staff Software Engineer, Payments Acquiring

About the Role

The Financial Platform Acquiring team owns the acquiring side of card payments for Square, Cash App, and Afterpay. When someone pays with a card at a Square seller, through Afterpay, or uses a card to move money in or out of Cash App, our systems make sure that payment happens correctly, every time.

We take in and tokenize card data from chip, tap, digital wallets, and online checkout, route each payment, and get it authorized over our direct network connections and acquiring partners. Then we capture, clear, and settle it, in the US and internationally.

As a Staff Software Engineer on the Acquiring team, you will bring deep card payments experience to some of the most complex technical work on our roadmap. That work includes expanding our direct network and acquirer connections, delivering network mandates, and making it cheaper and more reliable to accept cards. You will lead one or two of these projects at a time.

This is a hands-on role. You will build systems and tooling, debug at the message level, and turn your payments expertise into durable capabilities that other engineers can use. In your first year, you will ship at least one of those projects to production, leave behind standards and tooling that make the next one easier, and share what you learned elsewhere.

This role works US West Coast hours, from our Bay Area or Seattle offices or remotely within the Pacific time zone.

Responsibilities

• Bring deep card acceptance expertise to the team, reading network specifications, ISO 8583 messages, mandates, and interchange rules, and turning them into sound engineering decisions.
• Own the technical direction of your projects from design through production rollout, and lead the engineers working on them.
• Partner with our technical leads, product and finance operations partners, and stakeholders across Square, Cash App, and Afterpay to shape solutions where card-network requirements intersect with Block's acquiring platform.
• Stay deeply hands-on: write production code, build testing and certification tooling, analyze network messages, review designs and code, and debug issues down to the protocol and field level.
• Make and defend the technical calls on routing, retries, and processing cost, backed by data on authorization rates and fees.
• Establish shared frameworks, standards, tooling, and practices that make payments expertise durable.
• Raise the technical capability of engineers around you through design guidance, code reviews, mentorship, documentation, and clear technical judgment.
• Build with AI agents across the engineering lifecycle, and help set the patterns for using them safely on systems that move money.
• Share operational ownership of critical financial systems through on-call, incident response, and continuous improvements to reliability and correctness.

Qualifications

• Deep card payments experience at the message level: building or running integrations that talk to networks, acquirers, or processors (ISO 8583 or an acquirer's host format). Acquiring or merchant-side experience is ideal; direct network connection experience is a strong plus. ISO 20022 is a plus.
• Experience with the hard cases in real card transactions (partial and incremental authorizations, reversals, tips, currency conversion, interchange qualification).
• Strong hands-on software engineering experience building and operating highly reliable financial or payments systems at scale, with solid habits in design review, automated testing, and safe, observable rollouts.
• A track record of leading technically complex projects from design through delivery and setting technical direction for engineers.
• Experience creating durable technical leverage — frameworks, standards, tooling, architecture, or practices that other engineers and teams adopt.
• Broad understanding of end-to-end card payment flows: card data security and tokenization, routing, authorization, capture, clearing, settlement, reconciliation, interchange/processing costs, or chargebacks.
• Solid understanding of card network rules (Visa, Mastercard, American Express, Discover, and US debit networks) and payment processing ecosystem entities.
• Daily experience building with AI coding agents, and good judgment about when their output is right.
• Willingness to participate in an on-call rotation for critical financial systems.

Application Guidelines

• Candidates may submit up to 9 active applications within a 60-day period.
• Reapplications to the same role are accepted 90 days after a previous application has been reviewed.