Senior Rails + React Engineer: Team Accounts, Permissions & Payments

About LongFi LongFi uses a venue's existing enterprise-grade Wi-Fi to improve indoor cell coverage. We're live in 200+ venues across the U.S., connecting 7M+ mobile users a month, and work with partners including HPE Aruba, Ruckus, Cambium and the Wireless Broadband Alliance. Our platform manages the venues, partners and sites in our network, tracks network activity and handles partner payouts, so accuracy and security matter. It's a Ruby on Rails API with a Next.js/React frontend. The project We need a senior engineer to lead a focused, high-stakes project: moving partner access from links between individual user accounts to company accounts with roles (owner, admin, finance, read-only viewer), with some roles limited to selected sites. It touches authorization across the app, partner and admin screens, reporting and payouts. A first version already exists, and it's large: tens of thousands of lines across a series of pull requests. You will: - Review it critically and decide what to keep, rework or simplify - Split it into stages that can be reviewed and released safely behind feature flags - Plan and run the migration from the old access model with no downtime and a tested rollback plan - Prove that payouts and reports come out the same before and after - Pilot it with a few partners and roll it out Where this can go We're a small team that moves fast. If the project goes well, we'd like it to grow into a core role on the team. That means owning permissions and payouts going forward, working across the platform, and helping bring structure to how we build: architecture, code review standards, testing, CI and releases. You've done this before This matters most. You've personally led a change like this on a live product: - Moved a production app from single-user ownership to team or organization accounts with role-based access control - Migrated live data between models without downtime (backfills, dual paths, parity checks, staged cutover) - Worked on systems where a mistake means someone gets paid the wrong amount or sees data they shouldn't How you work - Clean, readable code in small, reviewable pull requests, with clear commits and meaningful tests - You've set up or improved a team's development process: code review, branching and releases, CI/CD, staging, feature flags - You design for scale and for failure: sound data models, background jobs, performance, monitoring - Security is part of how you build, not a final check: least privilege, tenant isolation, authorization tests, secure login and 2FA, audit trails, careful handling of secrets - You write things down: design docs, migration plans, runbooks Must have - 7+ years building production web apps, with deep Ruby on Rails experience (policy-based authorization such as Pundit, RSpec, background jobs) - Solid React and TypeScript - Strong PostgreSQL: schema design, large migrations, query performance - Experience architecting multi-tenant applications that scaled with the business - Excellent code review skills, including large changes you didn't write - Fluent Spanish and professional English, written and spoken - Based in Latin America, with at least 4 hours of overlap with US business hours Nice to have - Stripe Connect or other payout and ledger systems - ClickHouse or other analytics databases - Next.js, Sidekiq, Flipper, Sorbet - Wi-Fi, Passpoint or telecom systems How we'll start A short paid trial under NDA: review one part of the existing work and write up what you'd change and how you'd release it. Then the project itself, at 30-40 hours a week for about 3 to 6 months. If it's a good fit on both sides, we'd like to make it a long-term role on the core team. To apply Answer the screening questions, and tell us specifically about the account or permissions migration you led. Generic proposals won't be considered.