Backend Developer Needed — Client Onboarding Portal Creation

Overview
We need an experienced backend engineer to build the v1 backend for our SIMZ AI customer onboarding portal. This includes company login via UID + email OTP, a customer configuration API (questionnaire + integrations), and an internal admin review workflow with status updates and email notifications.

Core Requirements

Auth: Company UID (format XXXX-XXXX-XXXX-XXXX) + one-time 8-digit email verification code (single-use, ~5 min TTL) → JWT (scoped to company, ~1 hr TTL)

Customer APIs (JWT): save questionnaire progress (13 sections), manage integrations (webhook/CRM/etc.), mask API keys on read, optional test-connection endpoint

Submission Versioning: POST /submit creates an immutable submission snapshot; block new submission when latest status is Pending

Admin Portal APIs (internal auth): list/filter submissions, view company history, set status (Pending/Approved/Rejected/Requires_Action) with reason required for Approved/Rejected; trigger status email to customer

Data + Audit: PostgreSQL recommended (JSONB for questionnaire + snapshots), submission history, audit trail for auth attempts, submissions, admin status changes

Security: encrypt API keys at rest (AES-256 or equivalent), rate limiting on OTP endpoints, strict role-based access for admin endpoints

Deliverables
REST API implementation (v1 endpoints as above)
DB schema + migrations
Email templates + email delivery integration (SendGrid or AWS SES)
Basic logging/audit events and rate limiting

Tech Preference
Node/Express , JWT auth

More details will be provided upon acceptance.