Senior Software Engineer (Backend)
jawnt
Jawnt is a seed-stage startup at the intersection of fintech, hrtech, and mobility. We’re on a mission to make transportation more accessible by empowering employers to support their teams with commuter benefits while encouraging public transit and active transportation whenever possible.
About The Role
We’ve recently expanded our engineering team and are looking for a backend-leaning senior engineer who’s excited to build the systems that power funding, payments, and commuter benefits for hundreds of thousands of employees. As we scale across multiple complex domains- payments, accounting, and operations- this role offers an opportunity to have an outsized impact on Jawnt’s reliability and architecture. You’ll work closely in person with our Head of Engineering and the founding team to design, build, and own critical backend systems. This is an in-person role based in Brooklyn, New York City.
What You’ll Do
- Design, maintain, and extend Jawnt’s core platform APIs, built on FastAPI and PostgreSQL, that power funding, deductions, money movement, and operations
- Strengthen and scale Jawnt’s ledger, transaction, and card authorization technlogy, ensuring financial accuracy, reliability, and scalability across funding, spending, auditing
- Collaborate cross-functionally with product, design, and operations to translate complex real-world processes into scalable, software-backed tooling
- Instrument, monitor, and improve system performance using logging, observability, and alerting best practices (Datadog)
- Contribute and harden Jawnt’s deployment and infrastructure workflows built on Docker, GitHub Actions, and Kubernetes, ensuring secure, reliable, and repeatable releases.
- Shape engineering culture and technical standards, emphasizing testing, reliability, and operational excellence
Who You Are
- 5+ years of experience designing, building, and maintaining production backend systems
- Deep proficiency in Python, with experience in FastAPI, Flask, or similar frameworks
- Strong understanding of SQL and PostgreSQL, including schema design, query optimization, and data modeling
- Experience designing and consuming RESTful APIs (GraphQL a plus)
- Comfortable reasoning about money movement, data consistency, and transactional integrity
- Familiarity with containerized deployments and modern CI/CD workflows (Docker, GitHub Actions, Kubernetes)
- Pragmatic approach to testing and reliability- writing code that’s resilient and observable in production (monitoring, metrics, alerts)
- Based in NYC with a strong desire to work in person
Bonus Points
- Experience working in fintech, payments, or accounting systems- especially with ACH, card programs, or double-entry ledgers
- Familiarity with financial reconciliation, deferred funding, or scheduled disbursement flows
- Experience building internal or ops-facing tools to manage data and financial workflows
- Exposure to compliance frameworks such as SOC 2, PCI, or KYC/KYB systems
- Knowledge of Celery, SQLAlchemy, Pydantic, or Alembic
- Experience scaling backend systems for multi-tenant environments
- Background in observability and reliability engineering (metrics, traces, structured logging)
- Prior experience in early-stage startups, especially small teams shipping production systems quickly