Senior Backend Developer Python Jobs in Cincinnati, OH

We’re looking for a solutions‑oriented senior+ backend engineer to take real ownership of meaningful parts of our software. This is an orchestrator’s role: you’ll design and implement your own work and ship services that move money reliably, scale cleanly, and hold up under the kind of scrutiny that comes with operating in the financial system.

It’s time to rethink payments to the core.

Tesouro builds the embedded banking and FinOps infrastructure that lets banks and software platforms launch financial products without rebuilding the plumbing underneath. We sit in the critical path of real money movement, which includes payments, ledgers, invoicing, and the APIs our partners build their businesses on. Our work involves high trust and high stakes.

We’re a small, senior team that ships daily. Product defines the target, and you own the execution. We are expanding our team with engineers who can step in and take absolute ownership of the technical solutions.

You’ll work across our microservices architecture, make architecture decisions alongside the rest of the team, and have a direct hand in what we build for partners. We don't hand down hyper‑prescriptive tickets, but we don't expect you to guess, either. We need engineers who take a problem, actively design and iterate with Product, and ship robust solutions.

• Design, build, and operate backend services across our microservices platform
• Own features end to end: from shaping the approach with product and other engineers, through implementation, testing, deployment, monitoring, metrics, runbooks, and support.
• Make architecture choices collaboratively; we move fast, but we talk through the decisions that are hard to reverse.
• Integrate with partner banks, card networks, and third‑party providers, and help our partners succeed on top of what you build.
• Incorporate AI tools into your day‑to‑day workflow: planning, coding, testing, and technical documentation, and help the team think critically about where AI assistance improves quality versus where it introduces risk.
• Embed reliability into our daily workflow by continuously expanding test coverage and analyzing CI/CD pipelines to safeguard every rollout.

• Senior level or higher. You’ve owned significant backend systems in production and have the judgment that comes with it.
• Highly autonomous, and a strong collaborator. You can run with ambiguity without going dark. You know when to pull someone in before a hard‑to‑reverse call, rather than disappearing into a prompt.
• A genuine builder and fast learner. You ramp quickly on unfamiliar domains and you’d rather understand the why than just close the ticket.
• AI-fluent, human‑led. You get real leverage from AI tooling without handing over your judgment. You lead the model; you don’t follow it.
• Comfortable in a distributed systems / microservices world. APIs, asynchronous messaging, relational and non‑relational data, and the failure modes that come with all of it.
• US‑based. Cincinnati or Boston is preferred, as is anywhere we already operate, but we’ll talk to strong candidates anywhere in the continental US.

• AWS/EKS Experience
• Experience with React/JS Frameworks
• Payments, banking, or fintech experience

Our backend is primarily C# /.NET with Python in the mix, running as microservices on AWS and Kubernetes (EKS). We use PostgreSQL as our relational core and Cassandra for high‑throughput transaction processing, with Redis, RabbitMQ, and Kafka moving data between services. Our frontend web applications run on React in an NX monorepo.

We ship through ArgoCD and GitHub Actions, lean hard on automated testing (PACT contract tests, xUnit, Cucumber/Jest, Playwright), and run observability on Grafana and OpenTelemetry with PagerDuty for alerting. We’re PCI DSS v4.0 and SOC 2 certified, and security is a design requirement here, not an afterthought.

We use AI tooling in every phase of engineering, but we use it skeptically. Very few PRs are opened without some correction & improvement from our engineers. We expect engineers to orchestrate with it for brainstorming, prototyping, boilerplate, and test generation: anything that lets you spend more of your time on the hard problems. At the same time, your peers are your most valuable collaborators. What we don’t do is treat AI output as a finished product or a substitute for judgment. In fintech, correctness matters and money movements must be correct; a generated solution that’s 95% right isn’t good enough. We want engineers who know the difference, push back where AI missed the mark, and still find ways to ship faster because of the tools at their disposal. AI did it is never an excuse.