Senior Backend Engineer (Python, Payments & Multi-Tenant Systems)

Job Title: Senior Backend Engineer (Python, Payments & Multi-Tenant Systems)Location: RemoteCompensation: $6,000 – $9,000 USD/month (Negotiable)Schedule: Monday – Friday, 7:00 AM – 3:00 PM PSTContract / Project-Based EngagementRetainer option available after V1 launchWe’re hiring a Senior Backend Engineer to lead the end-to-end build of a secure B2B payments platform used by finance teams to manage vendor payments and bank file generation workflows.This is a high-ownership engineering role focused on backend architecture, multitenant system design, payment workflow security, and deterministic financial file generation. You’ll own the v1 product build from architecture through deployment while working directly with engineering leadership.The ideal candidate has deep experience building production-grade financial or security-sensitive systems and can independently ship scalable backend infrastructure with strong operational judgment.What You’ll Build:A multitenant Postgres-backed vendor and payments platform with strict tenant isolationSecure vendor management workflows with approval gates for bank detail changesRBAC authentication system with enforced 2FA for approvers and adminsPayment batch workflows supporting submission, approval, rejection, and audit trailsDeterministic payment file generation for bank ingestion workflowsAudit logging and timestamped change tracking across critical system actionsClean, production-ready APIs and backend servicesA scalable architecture supporting future tenant expansion without code changesFoundational infrastructure for future accounting integrations and automated upload workflowsWhat You’ll Own:Backend architecture and technical implementation for v1Database schema design, migrations, and tenant isolation strategyAuthentication, authorization, and session securityPayment workflow integrity and fraud-risk mitigationInfrastructure deployment and environment managementTechnical documentation and maintainable code standardsScalable system design supporting future product expansionWhat We’re Looking For:5+ years building production web applicationsProven experience designing multitenant systems with secure data isolationStrong Python backend engineering experienceDeep PostgreSQL expertise including indexing, migrations, and row-level securityExperience implementing RBAC, 2FA, and secure authentication workflowsExperience generating deterministic financial or institutional file formatsStrong understanding of audit logging and regulated workflow patternsExperience deploying production applications using platforms like Railway, Fly.io, Render, or similarAbility to independently own architecture decisions and deliveryStrong written communication and documentation skillsRequired Mindset:AI-native workflow using tools like Claude Code, Cursor, or equivalentSecurity-first engineering mentalityStrong product ownership and execution biasPreference for simple, maintainable systems over unnecessary complexityComfortable operating independently with minimal oversightNice-to-Haves:Payments, banking, fintech, or accounting integration experienceExperience with Playwright or browser automation workflowsFounder, agency, or startup-builder backgroundExperience building internal finance or operations products