Sr. Software Engineer II, Backend (Rust)

Software Engineer II with deep Rust expertise to own that surface end to end: the provider/vendor integrations, the verification logic, and the asynchronous delivery of outcomes into the systems that act on them.

You'll be NinjaTrader's Rust authority for the onboarding domain while working alongside Rust engineers across the wider Payward organization.

As the senior-most Rust engineer on the Onboarding squad, your work will significantly impact approval rates, time-to-funding, and our ability to extend the platform into new markets.

In this role you will:

• Design, develop, and maintain Rust services and crates that power account creation, identity verification, and KYC/CIP decisioning
• Build integrations with identity, fraud, and screening providers, including response modeling, deserialization, and fixture-based scenarios that make third-party behavior deterministically testable
• Write the determination logic as pure, table-tested functions, with one authoritative definition of each rule rather than the same rule reimplemented in three places
• Design asynchronous, task-based delivery of outcomes to downstream systems: idempotency keys, retry and resumption semantics, and completion gates that wait on a real receipt instead of assuming success
• Own data-handling correctness for flows carrying PII and identity documents, covering redaction and minimal projections, encryption in transit and at rest, secret management, and audit logging
• Express market and product differences as policy and configuration, so supporting a new jurisdiction is a policy change rather than a refactor
• Operate what you build: instrumentation, structured logging, alerting, and incident response for services where a silent failure quietly stops customers from funding
• Design and implement scalable, reliable service architecture, using cloud-based infrastructure such as Google Cloud Platform and Kubernetes
• Act as the onboarding domain's authority during cross-functional Rust design reviews, brokering technical contracts with external squads and mentoring internal engineers as they grow their Rust proficiency

What you'll need:

• 6+ years of professional software development experience, including substantial production Rust
• Strong command of Rust in production: ownership and lifetimes, error modeling, trait design, and the async ecosystem (tokio), plus serde and a SQL layer such as sqlx or diesel
• Demonstrated ability to write highly testable Rust, including pure functions at decision boundaries, table-driven tests, fixture-based integration testing, and strict contract tests
• Proven experience designing HTTP and event-driven service integrations, including versioning and backward compatibility
• Experience handling sensitive data under real constraints (encryption, secret management, least-privilege access, and audit requirements) in containerized cloud environments such as Docker and Kubernetes
• Demonstrated use of AI coding agents (Codex, Cursor, Claude Code) as a standard part of your engineering workflow, with the judgment to review and validate AI-assisted code before it ships
• Excellent communication, including driving technical contracts to agreement with teams outside your reporting line, and full ownership of what you ship
• Bachelor's or Master's degree in Computer Science, Software Engineering, or a related field (or equivalent practical experience)

Bonus Points for:

• Experience with identity verification, KYC/AML, CIP, or fraud and risk decisioning systems
• Experience in fintech, trading, brokerage, or crypto, particularly in a regulated financial services environment
• Experience in a large Rust monorepo with shared crates, workspace tooling, and multi-team code ownership
• Familiarity with policy-driven flow engines (YAML or JSON defined workflows), schema-driven contracts such as gRPC or protobuf, and feature flagging platforms such as Statsig
• Passion for futures, crypto, derivatives and trading technologies is a strong plus