Catalog
concept#Cloud#Platform#Architecture

Software-as-a-Service (SaaS)

A cloud delivery model where applications are hosted centrally and delivered to customers as subscription services.

Software-as-a-Service (SaaS) is a cloud delivery model where applications are hosted centrally and offered to customers as subscription services.
Established
Medium

Classification

  • Medium
  • Business
  • Architectural
  • Intermediate

Technical context

Identity providers (SAML, OIDC) for authenticationPayment and billing systemsMonitoring and observability tools (Prometheus, Grafana)

Principles & goals

Clear separation of responsibilities between provider and customer (shared responsibility).Automate operations, provisioning and updates.Data sovereignty and compliance must be addressed from the start.
Run
Enterprise, Domain

Use cases & scenarios

Compromises

  • Vendor lock-in via proprietary APIs or data formats.
  • Security and compliance breaches due to misconfiguration.
  • Cost explosion with inappropriate scaling strategy.
  • Automated tests and canary releases for safe rollouts.
  • Clear SLAs and transparent communication processes for customers.
  • Data classification and segmentation to safeguard data sovereignty.

I/O & resources

  • Application code and deployment artifacts
  • Cloud infrastructure or platform services
  • Security and compliance requirements
  • Provisioned SaaS instance with monitoring
  • Billing and usage reports
  • Operational and support processes for customers

Description

Software-as-a-Service (SaaS) is a cloud delivery model where applications are hosted centrally and offered to customers as subscription services. Users access software over the internet while providers manage operations, scaling and updates. The model affects cost structures, integration patterns, security, and organizational responsibilities like tenancy and data ownership.

✔

  • Faster customer access without local installation.
  • Centralized operations and consistent updates.
  • Scalability and flexible cost models via subscriptions.

✖

  • Limited control over infrastructure and release timing.
  • Challenges with specific integration requirements.
  • Possible regulatory constraints regarding data residency.

  • Availability (Uptime)

    Percentage of time the service is reachable.

  • Customer retention rate

    Share of customers remaining active over a defined period.

  • Operational cost per customer (OPEX per customer)

    Average ongoing costs calculated per customer or tenant.

Office suites as SaaS

Productivity applications hosted centrally and offered by subscription.

Cloud CRM systems

Customer relationship management as a managed, multi-tenant service.

Industry software as hosted solution

Specialized applications operated centrally for many customers.

1

Define strategy: target customers, multi-tenancy model and pricing.

2

Adapt architecture: design tenant isolation, scalability and observability.

3

Build infrastructure and CI/CD: set up automated provisioning and rollouts.

4

Implement security and compliance processes.

5

Migrate pilot customers and establish feedback loop.

⚠️ Technical debt & bottlenecks

  • Short-term integrations implemented without standardization.
  • Missing observability in critical paths.
  • Monolithic architecture that becomes blocking for refactoring.
Data migrationIntegrationsOperational automation
  • Hosting an on-premise instance unchanged and calling it 'SaaS' without multi-tenancy.
  • Compromising data security for speed to market.
  • Omitting monitoring and SLAs in production customer environments.
  • Underestimating data migration costs and complexity.
  • Ignoring regulatory requirements in target markets.
  • Hidden costs from misconfigured scaling.
Cloud architecture and operational automationSecurity and privacy (compliance requirements)DevOps and release engineering skills
Multi-tenancy and tenant isolationScalability and elasticitySecurity, privacy and compliance
  • • Regulatory requirements for data sovereignty and location.
  • • Dependency on cloud provider services and SLAs.
  • • Requirement for reliable network and internet connectivity.