Backend/Platform Engineer (Founding Lead) — Remote US — Equity-Only

Join as a founding member building payment infrastructure for MCP so AI agents can pay and be paid. You won’t be “hired into a box” — you’ll set the standards, choose the building blocks, and leave your fingerprint on product, culture, and code that moves real money across cards, crypto, and e-wallets.Ownership that matters. This is Equity-Only until funding with substantial equity (standard 4-year vesting, 1-year cliff). Our plan is to start a base salary within 3 months of your start date - and likely earlier upon pre-seed close. Equity now, salary soon, and growing with subsequent rounds.The RoleFounding lead engineer owning the core of our multi-rail payment platform. You’ll make decisive, hands-on contributions across backend and infra while setting engineering standards. Early on, expect to be a bit full-stack and help maintain/extend our SDKs.Responsibilities (concise)Design, build, and operate payment orchestration (card/ACH/crypto/e-wallet), with clear idempotency, retries, and fallbacks.Establish a secure credential vault/tokenization strategy (3rd-party vault or KMS/HSM + Vault) to keep PCI scope lean.Implement policy/routing and basic risk controls; build a lightweight ledger and reconciliation jobs.Ship developer-grade APIs and improve DX (errors, docs, quickstarts); partner with DevRel on examples.Stand up observability & SLOs (latency, availability, approval rate) and own on-call readiness.Collaborate closely with Compliance/Risk on boundaries (PCI, KYC/KYB, disputes).Testing ownership: maintain unit/integration/contract tests and CI for critical paths.RequirementsMust-Have6+ years building backend/platform systems (preferably in payments/fintech or other high-integrity domains).Practical expertise with auth/capture/refund flows, consistency patterns, and reliability at scale.Strong in at least one of Go/Java/Kotlin/Rust/Node.js/Python and solid SQL.Cloud & infra proficiency (AWS/GCP, containers/K8s, IaC), with a security-first mindset.Clear communicator and hands-on lead who mentors and sets engineering quality bars.Highly PreferredFamiliarity with MCP (Model Context Protocol).Comfort with Python & TypeScript; willingness to be full-stack early and help maintain/extend the SDKs.Strong testing habit (unit/integration/contract/E2E) and CI discipline.Experience with processors/gateways (e.g., Stripe/Adyen) or issuers/BaaS (e.g., Marqeta/Lithic), and with vault/tokenization approaches.Compensation & SetupEquity-Only until pre-seed with substantial equity, subject to standard 4-year vesting with 1-year cliff and IP/confidentiality.After pre-seed, we introduce a base salary (modest at first) that grows with subsequent rounds.Remote within US time zones; async-friendly, fast decisions.Keywords: Backend/Platform Engineer, Payments Engineer, Fintech, API/SDK, Idempotency, Distributed Systems, AWS, Postgres, Kafka, Kubernetes, Python, TypeScript, MCP (Model Context Protocol), Developer Tools.