> For the complete documentation index, see [llms.txt](https://developer.harness.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.harness.io/harness-cloud-operations/harness_services_architecture.md).

# Harness SaaS Services Architecture

<figure><img src="/files/1KSYF1TBuuCjg598rSPx" alt="Harness microservices architecture in the Prod1 logical cluster"><figcaption><p>Click to view full size image</p></figcaption></figure>

This diagram provides an overview of Harness microservices in the Prod1 logical cluster. The architecture has three distinct layers:

1. **Platform layer**: The bottom layer contains Platform Services, which provide core Harness functions. These services manage delegates, pipelines, secrets, and other platform functions.
2. **Module layer**: The middle layer contains Feature Flags (FF), Cloud Cost Management (CCM), Continuous Integration (CI), Continuous Delivery (CD), and other modules. Each module has services for its domain. Module services interact with Platform Services to perform their functions.
3. **Aggregator and UI services**: The top layer contains Aggregator and user interface (UI) services. Gateway and Auth UI are common to Prod1 and Prod2. Gateway manages authentication, IP allowlists, and request-cluster redirection.

Higher-layer services invoke lower-layer services to fulfil their functions. Services communicate with each other using both synchronous and asynchronous patterns.