Senior Backend Engineer — Multi-Tenant SaaS + Payments (TypeScript/Node + Postgres)

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: TYPE OF WORK

Full Time

: WAGE / SALARY

$1,500–$1,600 USD/month

: HOURS PER WEEK

TBD

: DATE UPDATED

Jun 17, 2026

JOB OVERVIEW

Be one of two senior engineers who set the quality bar for the software that real truck-repair shops run their entire business on.

We're WrenchEngine — the operational platform a heavy-duty truck & trailer repair shop runs on: work orders, billing, inventory, managed-maintenance, on a multi-tenant / multi-brand foundation with an AI layer on top. Our first customer is an enterprise multi-brand fleet-services company; we're replacing their existing shop software and going live at a pilot shop this fall. Real shops will invoice real money on what you ship.

We build fast with AI (Claude Code is core to how we work), so the bottleneck isn't typing — it's senior review on the two things that can sink us: money-path correctness (invoices, payments, pricing, cores) and multi-tenant data isolation. We have one senior engineer today. You're the second, hired so neither of those rests on one person.

What you'll own:

Final review on tenant/brand isolation — no query ever crosses a tenant boundary, no data leaks between brands. We have a real isolation system (query-layer guard + Postgres row-level security + composite FKs) that's actively being hardened. You own it.
Backup review on the money path (invoicing, pricing, cores) so it's never a single point of failure.
Lead a reversible data migration: moving a customer off their old system into ours, with a tested rollback path and dual-run sync.
Rigorously review AI-generated code — judgment about what's correct and safe matters more than raw output.
Our stack (this is what you'll work in):

TypeScript (strict) monorepo, pnpm + Turbo
Backend: Node + Express, raw SQL over PostgreSQL, layered controller ? service ? repository (~480 endpoints, ~190 SQL migrations)
NATS JetStream for events, Redis cache, Typesense search, S3/MinIO storage
Multi-tenant: brand = organization, group ? brand ? shop, enforced by a scoped-query chokepoint that throws on a missing tenant filter, plus Postgres FORCE row-level security
Auth: FusionAuth (OAuth2), JWT
Frontend: Next.js 15 / React 19 (you don't need to be FE-strong, but it helps)
Integrations: QuickBooks/Intuit, Fullbay, Mitchell 1, GPS telematics, Twilio, SendGrid
~240 backend test files (130+ integration) — tests are the contract here
Must-haves:

Senior backend engineer, strong in TypeScript/Node + PostgreSQL
Real multi-tenant SaaS experience — you've designed or owned tenant data isolation, not just used it
Security fundamentals (authz boundaries, RLS or equivalent, least-privilege)
Payments / financial-integration experience (invoices, pricing, ledgers, or accounting integrations)
A disciplined code reviewer who can explain why a change is safe or not
Comfortable owning data migrations and third-party integrations
Nice-to-have:

Fleet / field-service / automotive or accounting-integration (QuickBooks) domain experience
Experience reviewing/steering AI-generated code
How we work: Small, senior, async team. 2-week sprints with a hard definition of done — tests green, TypeScript strict, tenant-scoped, money-path/security reviewed, merged to main. Remote, Philippines-based.

To apply — read carefully (we filter for this):
Start your reply with the word "WRENCH" so we know you read the post. Then tell us briefly:

A multi-tenant system where you owned data isolation — how did you enforce it?
A money-path or financial bug you caught (or prevented in review).
A data migration or system cutover you led.
Link code or write-ups if you have them. We read for judgment, not buzzwords. Applications that don't follow these instructions won't be reviewed

SKILL REQUIREMENT

Node JS Typescript PostgreSQL

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Senior Backend Engineer — Multi-Tenant SaaS + Payments (TypeScript/Node + Postgres)

Please login or register as jobseeker to apply for this job.

TYPE OF WORK

WAGE / SALARY

HOURS PER WEEK

DATE UPDATED

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