SaaS Multi Tenant Architecture Explained
Multi-tenancy is the defining technical pattern of every B2B SaaS. One application serving multiple organisations with complete data isolation, the Bubble.io implementation, and why structural multi-tenancy is not the same as secure multi-tenancy.
How One Application Serves Multiple Organisations Securely
SaaS multi-tenant architecture is a software design where a single application instance serves multiple customer organisations simultaneously with each tenant’s data completely isolated from every other tenant at the database level. In a multi-tenant SaaS, Company A and Company B use the same application and database tables but can only access their own records. Multi-tenancy is enforced by row-level access control (privacy rules in Bubble.io) running before any query returns data. It is the defining technical pattern of every B2B SaaS product.
Multi-tenant isolation is not automatic. It must be deliberately designed into the data model and enforced by access control rules. SA finds missing or incomplete multi-tenant isolation in the majority of Bubble.io applications it audits.
How SA Builds It in Bubble.io
| Component | Purpose | Implementation |
|---|---|---|
| Workspace data type | Tenant boundary; each organisation has one record | Create on org signup; link all app data to its Workspace |
| Membership data type | Links users to workspaces with role | User + Workspace + Role + Status; checked on every access |
| Workspace field on all types | Scopes every record to its organisation | Add to every data type; set on creation; never change |
| Privacy rules on all types | Database-level access control | Condition: active Membership linking Current User to this record’s workspace |
When Each Architecture Makes Sense
Multi-tenant (standard SaaS)
One application serves all customers. Data isolated at row level. Most cost-efficient and scalable. Standard for all B2B SaaS.
Single-tenant (dedicated instance)
Each customer has their own application and database. Higher cost, higher isolation. Required by some enterprise or government customers with strict data residency needs.
Hybrid multi-tenant
Standard multi-tenant for most customers; dedicated instances for specific enterprise accounts with regulatory requirements. Most complex to manage.
Free SaaS Tech Audit — 30 Minutes
Athar Ahmad personally reviews your SaaS: security gaps, billing mistakes, and performance issues identified before they cost you customers or deals.
- Multi-tenant security and privacy rule assessment
- Stripe billing architecture review
- Performance bottleneck identification
- Written remediation roadmap within 24 hours
Common Questions
Q: What is the difference between multi-tenant and multi-user SaaS?
Multi-user means multiple users access the same account. Multi-tenant means multiple organisations share the same application infrastructure with data isolation between them.
Q: How do I implement multi-tenant architecture in Bubble.io?
Four steps: create a Workspace data type, add a workspace field to every application data type, set a privacy rule on every type checking for active workspace Membership, and run the two-browser isolation test before every production deployment.
Q: Can a SaaS be multi-tenant but not secure?
Yes. The workspace field provides structure; privacy rules provide security. Many Bubble SaaS products have the workspace field but missing or incomplete privacy rules. The two-browser isolation test is the only way to confirm the implementation is actually secure.
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