Fernanda Souza (@FernandaSo52511)

Senior Backend Engineer (AI + Payments) We’re building a global, API-first payments platform. The core is already live — payments API, ledger, commerce, checkout, dashboards, infrastructure. Much of the codebase has been generated by AI. 💰 $30k–$40k/month · Remote · Contractor We need someone who can look at all of this and say: “this will break in production” — before it actually does. What already exists - Full payments API (PaymentIntents, Refunds, Customers, Charges) - Double-entry ledger with atomic entries - Native commerce engine (Products, Orders, Fulfillment, Inventory) - Hosted checkout, Merchant Dashboard, Admin Portal — all deployed - API Gateway in Go (auth, rate limiting, circuit breaking) - 60+ PostgreSQL tables, strict TypeScript, versioned migrations - Async workflows for webhook delivery and settlement - Terraform managing 183+ AWS resources - CI/CD with smoke tests and automated deploys Your mission Be the last line of defense between code and real money. Concretely: 1. “This will break in production” Identify failure points before they cause downtime — silent crashes, missing restart policies, monitoring gaps, non-recovering processes 2. “This code will cost us money” Double charges, race conditions in the ledger, lack of idempotency, unsafe refund/dispute flows, incomplete reconciliation 3. “This is a security risk” Exposed secrets, missing encryption at rest, misconfigured VPCs, unauthenticated endpoints, injection vectors in AI-generated code 4. “This database will fail” Unsafe migrations, lack of backup/disaster recovery, unindexed queries, broken transactions, schema changes causing downtime Day-to-day - Deep audit of AI-generated backend code (TypeScript + Go) - Review financial flows to identify edge cases that could cause losses - Validate infrastructure decisions and highlight reliability risks - Build integration tests proving critical flows work end-to-end - Ensure observability is strong enough to detect issues in minutes, not hours Stack TypeScript · Hono.js · Drizzle ORM · Go · PostgreSQL (Aurora Serverless) · Redis · Temporal · Docker · AWS ECS Fargate · Terraform · Cloudflare We’re looking for someone who - Has 5+ years in backend engineering, preferably in fintech/payments - Has operated production systems handling real money — incidents, postmortems, on-call - Can audit AI-generated code and spot what AI misses - Has strong intuition for “this will break” before it does - Knows PostgreSQL deeply (transactions, locking, migration safety, disaster recovery) - Has experience with observability (tracing, alerting, runbooks) - Values accuracy over speed — a ledger bug in production is worse than a week of delay Nice to have - Experience with PCI DSS compliance - Familiarity with double-entry ledger systems - Experience with Temporal or distributed workflows - Go for high-performance services - Experience finding (and fixing) financial bugs in production 🔗 Application Form: https://form.typeform.com/to/aQt51Pfi