Software Engineer / Senior Software Engineer

Job Description Most engineering job descriptions read like a checklist. This one is different. At pmtbox (“Payment Box”), we’re building a fintech that drives real outcomes for merchants as it relates to their payments/interchange optimization, fraud, and chargebacks/disputes. We’re a VC-backed fintech with a small team, over 1,000 active clients, and big ambitions, and we’re looking for engineers who want to build things, not just complete tickets. If you’ve spent your career in a dev shop where product managers feed you Jira tickets all day … this role might feel very different. We’re looking for engineers who: Build things on their ownAre comfortable working within systems and workflows and thinking of ways to improve processesUse AI as a force multiplier in your development workflow Enjoy solving complex problems that span the layered architecture of web applications What You Might Work On You’ll be building real products alongside founders, including a technical co-founder with deep industry experience and expertise, and a small, high-performing engineering team. Expect to: Design and build product features within a structured Rails codebase using a tests-first approach in a CI/CD environmentImprove internal tooling, automation and data workflowsBuild integrations with mid-market and enterprise clientsUse and refine AI-assisted development workflows and toolsContribute to architectural decisions as our platform's data model and intelligence layer grows How Our Engineering Team Works This is not a role where everything is already defined, but it’s also not greenfield. You’ll be building within established patterns and codebases. Our engineering team is small and deliberately so. We currently support over 1,000 active clients across a Rails/Postgres stack with AI-assisted development workflows integrated into daily work. We maintain a TDD-first codebase with CI pipelines, and structured project context that keeps both humans and AI tools oriented. This isn't a “move fast and break things” environment; it's a “move fast because the guardrails are good” kind of environment. You'll have real autonomy within well-defined boundaries: a tested codebase, clear architectural patterns, and context documentation that means you can ship independently without waiting for someone to unblock you. What We’re Looking For We care less about years of experience and more about how you think and what you’ve built. You might be a great fit if you: Have experience with PHP, Python, or RubyCan show things you’ve built yourself: GitHub projects, side tools, automation scripts, or personal software projects are great to share with usThink beyond coding and into systems and workflowsAre curious about how AI changes how software gets built We use AI-assisted development workflows daily as part of our core infrastructure. We’re looking for engineers who’ve already started building their own workflows and can demonstrate: : A project where AI assistance measurably changed your development speed or approachHow you support AI workflows with other scripts or tools when it doesn’t work to one-shot itKnowledge of how to feed data into the AI so that it can deliver quality resultsA workflow you built to validate the output from an AI workflowA workflow where you learned that AI confidently lied to you and what you did to build around that We want engineers who understand where AI helps the workflows and where it breaks down, not just the latest tools and methods The Kind Of Engineer Who Thrives Here You’ll probably enjoy this role if you: Like solving ambiguous problemsPrefer building over attending meetingsHave shipped things without being told exactly what to doEnjoy improving systems and processesWant real ownership of what you build Our Stack (and What We’re Exploring) Our team works across modern backend technologies and is constantly experimenting with better tools and workflows. Current and emerging technologies include: Ruby / RailsPostgresAI-assisted development workflowsModern cloud infrastructure We’re far more interested in how you solve problems than whether you’ve used a specific framework. Why Join pmtbox Early-stage fintech with real momentum and VC-backing by Tandem Ventures (Founders of fintech unicorns Divvy, Finicity, etc.)Small team, high ownershipWork on meaningful ecommerce infrastructureBuild alongside founders and experienced operators in a four-days-a-week in-office culture (with one work from home day per week on Wednesdays)Competitive compensation and benefits package including enterprise-level medical, dental, vision, 401k, and generous time off We’re looking for builders. If you want a highly structured environment where everything has already been mapped out and every ticket tells you exactly what to build, this probably isn’t the right fit. If you like figuring out how systems work, connecting things that weren't originally designed to work together, and building infrastructure that can eventually become a product in its own right, we'd love to meet you.