Building a Secure Multi-Tenant SaaS with Laravel and Next.js

Introduction

Modern software is often delivered as a SaaS platform a single system that serves multiple companies (tenants), each with its own data, workflows, and users. A key requirement is strong data isolation to prevent cross-tenant access.

In this article, we explain how we built a secure, scalable multi-tenant SaaS using Laravel for backend APIs, Next.js for the frontend, PostgreSQL for shared storage, and Stancl Tenancy for tenant management all running on a single domain and single database.

The Core Idea

Our goal was a SaaS platform that:

• Serves multiple companies (tenants) in one system
• Keeps each tenant's data fully isolated
• Runs on a single domain without subdomains
• Supports multiple user roles such as admins, managers, team members, and support staff
• Scales efficiently as new tenants join

Tech Stack

• Laravel 12 – backend APIs and business logic
• Next.js – frontend dashboard and interface
• Tailwind CSS – styling and responsive design
• PostgreSQL – shared relational database
• Stancl Tenancy – multi-tenancy management
• Spatie Roles & Permissions – role-based access control
• Laravel Sanctum – secure token authentication

How Multi-Tenancy Works

Instead of creating a separate database per tenant, we store all tenant data in shared tables and assign a tenant_id to every row. This approach is easier to maintain and scales better.

Example Table Structure

• users: id, name, email, password, tenant_id
• projects: id, title, description, tenant_id
• roles: id, name, tenant_id
• permissions: id, name, tenant_id
• resources: id, name, project_id, tenant_id

When a user logs in, their tenant_id is identified, and every query automatically filters data to that tenant. This ensures full isolation across tenants.

Roles and Permissions

Tenant Roles

• Admin – full access to tenant settings and management
• Manager – can manage projects and assign tasks
• Team Member – can view and update assigned projects or tasks
• Support – assists users and resolves internal queries

Platform (SaaS Owner) Roles

• Site Admin – global access to all tenants and platform settings
• Support Staff – assists multiple tenants, handles escalations

Authentication with Laravel Sanctum

Users log in via Next.js frontend and receive a secure token from Laravel Sanctum. The token identifies their tenant context. All subsequent API calls automatically use this tenant context to ensure data isolation.

Platform admins log in through a separate backend dashboard (Filament or Nova), avoiding conflicts between tenant users and global users.

Registration Flow

1. User signs up via frontend form.
2. Data is sent to Laravel API.
3. Laravel creates a new tenant record.
4. Saves company information (name, logo, tax info).
5. Creates the first user as Admin for that tenant.
6. Seeds roles and permissions for the tenant.
7. Returns a Sanctum token so the user can access the platform.

Why No Subdomains

• Single top-level domain (yourapp.com)
• Tenant context is determined by token, not subdomain
• Simpler SSL setup and API integration
• Smoother frontend routing with Next.js

Security Measures

• Tenant-scoped queries to prevent cross-tenant access
• Encrypted file storage for projects/resources
• Role-based authorization for all actions
• Audit logs with timestamps and IP addresses
• PCI-compliant payment gateways for any transactions

Lessons Learned

1. Start simple one database can support many tenants initially.
2. Use trusted packages Stancl Tenancy + Spatie Permissions save months of effort.
3. Always include tenant_id in key tables for isolation.
4. Define roles early clarity simplifies development and security.
5. Separate admin panel keep platform-wide users distinct from tenant users.

Conclusion

Using Laravel, Next.js, and a tenant-aware architecture, we built a secure, scalable SaaS platform serving multiple companies on a single system no subdomains, no complexity.

This architecture is perfect for multi-tenant SaaS applications such as project management, collaboration platforms, CRMs, or internal resource management tools.

Ready to implement your own multi-tenant SaaS? Contact our team.