Jawnt Backend Software EngineerJawnt 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: Our in-person NYC engineering team is growing, and we're looking to add a backend-leaning software engineer to help build the systems that power our commuter benefits platform: the workflows, financial operations, and payment rails that move millions of dollars between employers, employees, and transit agencies. As we scale across fintech, HR, and mobility, the role offers the opportunity to have outsized impact on both our customer and internal products.
You'll work closely in person with our engineering team, contributing major technical decisions and helping shape the future of the company. This is an in-person role based in Brooklyn, NY. Our office is located in Dumbo.What You'll DoDesign and implement backend services in Python and FastAPI that power the customer-facing surfaces of our commuter benefits platform: enrollment, deductions, claims, and card managementOwn the flow-of-funds infrastructure that moves money between employers, employees, transit agencies, and card networks- invoicing, settlement, reconciliation, and everything in betweenBuild and harden the real-time systems behind card authorization decisions - low latency, high availability, no room for ambiguity behind every card tapPartner with operations to design and ship internal tools that make complex payment operations- exception handling, refunds, disputes, reissues- fast and reliableDefine backend processes for monitoring, testing, and verification that balance speed of iteration with the correctness and auditability financial systems demandReach into the frontend (Next.js, TypeScript) when a feature needs it end-to-end, especially on the internal tools ops lives inShape our engineering culture, code standards, and tooling as we scale the teamWho You Are5+ years of experience building and maintaining production backend systemsDeep proficiency in Python, both in RESTful APIs (FastAPI, Flask) and event-driven architecture and async workflow processing (Celery, Temporal)Strong instincts for concurrency, retries, idempotency, and failure modes in distributed systemsStrong experience with relational databases (schema design, locks, query performance, migrations)Prior experience with payments, card issuing, ledgers, or other financial systems where correctness under partial failure isn't optionalComfortable instrumenting and debugging production systems (logs, metrics, traces, load testing)Working proficiency in TypeScript and React / Next.js, enough to ship a full feature without a frontend handoffStrong communicator who can sit with ambiguity, whiteboard a flow, and align across product and opsFamiliarity with testing strategies across the stack (unit, integration, E2E)Based in NYC with a strong desire to work in personBonus PointsExperience in fast growing technology companies, especially with lean teams and fast-paced iterationFamiliarity with modern cloud infrastructure, infrastructure-as-code, and CI/CD pipelines (Kubernetes, Terraform, Github Actions)Background in fintech, payments, or financial operations (ledgers, reconciliation, payments, card issuance, or similar)Experience with card issuing platforms (Marqeta, Unit, Stripe Issuing, Lithic), invoicing platforms (Stripe Invoicing, Quickbooks, etc), and other common financial products (e.g Plaid)Prior work on internal tools (admin panels, operations-facing UIs, financial plumbing)