The x-tenant-id Pattern: Multi-Tenant API Without Multi-Tenant Complexity

Short summary

A practical pattern for multi-tenant API scoping using a custom x-tenant-id header combined with JWT authentication. The article compares three approaches — subdomain, path-based, and header-based tenant identification — and implements the header approach with middleware that validates tenant membership against the authenticated user. This pattern keeps routes clean, supports single-user-multi-tenant access, and applies tenant context uniformly at the router level.

• •x-tenant-id header + JWT auth for clean multi-tenant API scoping
• •Middleware chain: auth first, then tenant context validation against user memberships
• •Router-level middleware application ensures new routes inherit tenant context automatically

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