# Senior Software Engineer, Ledgering

**Company:** [Square](https://hotfix.jobs/companies/square)
**Location:** San Francisco, CA, New York, NY
**Role:** Fullstack Engineering
**Salary:** $185k – $327k/yr
**Experience:** 8+ years
**Skills:** Java, Kotlin, Go, SQL, Distributed Systems, ledgers, double-entry accounting, settlement systems, treasury systems, AI Agents, AWS, Kubernetes, Terraform
**Posted:** 2026-07-21

> Senior Software Engineer building and operating Block's core ledgering, balance, transaction, and settlement systems that serve as the financial source of truth for Square and Cash App. Requires 8+ years experience with distributed high-throughput systems and financial domain knowledge (ledgers, accounting, treasury).

## Job Description

## Responsibilities
- Design, build, and operate the balance and transaction systems of record that serve as the financial source of truth for millions of merchants and customers.
- Build settlement orchestration that determines how account holders get paid: schedules, amounts, deposit methods, and withholdings.
- Develop self-serve ledgering APIs with durable semantics and clear contracts, so partner teams can stand up a new balance or transaction type in about a day instead of waiting weeks on custom integration work.
- Emit balance and settlement data that downstream finance, reconciliation, and reporting teams can trust, against agreed data contracts.
- Design and implement reliable, high-volume distributed transaction-processing systems, making thoughtful tradeoffs between consistency and availability when both are not possible.
- Drive convergence across a large portfolio of financial services: consistent transaction and balance models, shared workflow tooling, and predictable integration patterns.
- Operate tier-0 and tier-1 financial systems against published SLOs, and debug production issues across services and multiple levels of the stack in a high-reliability environment.
- Work AI-natively: use AI agents throughout the development lifecycle, and build agents and automation that reduce operational toil across our services.
- Lead complex projects end to end, breaking the work into components and milestones that other engineers can pick up.
- Mentor other engineers and contribute to the technical direction of the team.
- Work with engineers, product managers, and finance and treasury stakeholders across the company to ship new capabilities at scale.

## Requirements
- A minimum of 8 years of related experience with a Bachelor's degree; or 6 years and a Master's degree; or a PhD with 3 years experience; or equivalent experience.
- Experience designing and operating distributed, high-throughput, fault-tolerant services, with a strong understanding of consistency, idempotency, and failure handling.
- Experience building money-movement systems such as ledgers, double-entry accounting, settlement, or treasury, or the curiosity and drive to build deep expertise in the domain.
- Proficiency in at least one major programming language (for example Java, Kotlin, or Go) and strong SQL.
- Experience leading complex, ambiguous projects across multiple engineering teams and driving clear next steps in areas without clear ownership.
- High standards for software architecture and engineering practices, including maintainable and testable code, CI/CD, and observability, in a complex, high-stakes financial environment.
- Proficiency in using AI tools throughout the software development lifecycle to improve engineering productivity, problem solving, and software delivery.
- Strong written and verbal communication skills.

## Nice-to-Haves
- Technologies We Use and Teach: Java, Kotlin, Python, AI agents and tooling across the development lifecycle (including AMP, Codex, Claude, Goose and MCP), Temporal, Protocol Buffers, jOOQ, GraphQL, MySQL, Aurora, Vitess, Databricks, Snowflake, AWS, Kubernetes, Terraform, Datadog.

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