APIs have become crucial for modern web platforms, enabling seamless communication between different systems and services without requiring everything to reside in a single application.
WordPress has had its REST API for many years, offering extensive breadth and ecosystem support. It’s possible to use WordPress as a headless CMS, where WordPress manages content while a separate frontend is built using frameworks like React, Vue, or Next.js.
SiteAdmin’s API is newer. The foundation is already in place and used, for example, by SiteAdmin Local, but the API is still under development. New features and services are added incrementally.
WordPress as a Headless CMS
WordPress doesn’t need to be the website visitors see. With a headless approach, WordPress can function as a CMS, sending content via REST API to a separate frontend.
A frontend can then fetch pages and posts and build the website itself.
WordPress
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REST API / JSON
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React / Vue / Next.js
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Ready website
This approach offers developers significant freedom. WordPress also boasts a vast ecosystem with numerous ready-made integrations and tools around its API.
This is a clear strength of WordPress.
SiteAdmin API as Part of Zethron
SiteAdmin’s API isn’t a standalone solution for a single SiteAdmin function. It’s part of Zethron’s unified platform API, where multiple services can communicate through a common base API structure.
The API uses a unified structure:
/api/v1/{service}/...
Examples of services within the platform include SiteAdmin, WP Kit, Mailio, and Bridge. New API functionalities can be developed within the same structure without each service needing to create its own system for authentication and access.
SiteAdmin API is still under development. This doesn’t mean the API is missing or just a future idea. The foundation is already in place and used, but not all components of a complete, general content API are fully developed yet.
How SiteAdmin Local Works
SiteAdmin Local is a lightweight client running on the customer’s own hosting. The administration, content, design, and publishing remain within SiteAdmin.
When a visitor opens a URL on the customer’s website, Local receives the request and queries SiteAdmin API for the page.
Visitor
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Customer’s Website
↓
SiteAdmin Local
↓
SiteAdmin API
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Rendered HTML
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SiteAdmin Local
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Visitor
The key here is that SiteAdmin API currently primarily functions as a render API. Local doesn’t need to build the page from separate content objects.
The API receives a URL and returns the fully rendered page as HTML.
A Concrete Example of SiteAdmin API
One API call looks like this:
POST /api/v1/siteadmin/render/page
Local sends its authentication details and information about the URL to render. The API then returns the fully rendered page.
There are also other endpoints for connection tests and Local client management:
GET /api/v1/siteadmin/ping
POST /api/v1/siteadmin/render/page
GET /api/v1/siteadmin/hosting/bootstrap
POST /api/v1/siteadmin/hosting/status
The same rendering principle is used for sitemaps like sitemap.xml, robots.txt, and llms.txt.
API Returns More Than Just a Page
When SiteAdmin renders a page, it’s built from the current website content and settings.
This can include:
- Pages and subpages
- Blog posts
- Blog archives, categories, and tags
- Menus for header and footer
- Images and other media
- SEO settings
- Website design and information
- Language versions
If a visitor opens /en/contact, Local can ask SiteAdmin for that specific URL and receive the English version of the page.
Other functionalities can also use the same rendering engine when the respective module is active, such as a shop, guestbook, or other types of content.
SiteAdmin API Uses JSON and Modern Authentication
Even though the response from SiteAdmin Local is a fully rendered HTML page, communication with the platform is based on a modern API using JSON-based requests and clear authentication.
Each website has its own API key, used as a Bearer token:
Authorization: Bearer sa_live_...
The API key is linked to the correct service and resource. A SiteAdmin key cannot be used to fetch content from another website.
Keys can be rotated and revoked. Communication requires HTTPS, API calls are limited per minute, and requests are logged with details like URL, status, and timestamp.
This ensures the API can serve as a secure foundation for multiple services within the Zethron platform.
SiteAdmin API Isn’t Fully Ready Yet – And That’s Important to Say
Here’s a key difference between SiteAdmin and WordPress.
WordPress REST API is much more mature and comprehensive. There are established endpoints for many types of content and functions, and a large ecosystem builds on top of it.
SiteAdmin API is newer and doesn’t yet have the same breadth.
Currently, a central part is the ability to render a SiteAdmin website via API, which makes SiteAdmin Local possible. There’s also a unified API structure within Zethron that other services use.
More API functions are being developed incrementally. This means a more general content API, where pages and posts are fetched as separate posts, is a potential future development—but it shouldn’t be presented as a fully developed feature until it exists.
WordPress or SiteAdmin?
| Area | WordPress | SiteAdmin |
|---|---|---|
| API | Highly mature REST API | Younger API under development |
| Headless | Yes, well-established support | Not classic headless; SiteAdmin Local uses a separate client and render-API |
| Frontend | Can be built entirely separately | Local displays the fully rendered page from SiteAdmin |
| API Ecosystem | Very large | Built within Zethron’s unified platform API |
| API Authentication | Multiple established solutions | Resource-specific API keys, Bearer auth, HTTPS, and rate limiting |
| Separate Web Hosting | Possible to build headless in various ways | SiteAdmin Local is built for this |
Different Solutions for Different Needs
WordPress offers a significant advantage if you want to build a fully independent headless system, controlling the frontend, data flow, and API integrations yourself. The ecosystem is vast, and there are many ready-made tools to start from.
SiteAdmin takes a different approach. The platform consolidates administration, content, and rendering, while SiteAdmin Local allows placing the website client on the customer’s own hosting.
This means you can have the website on different hosting without moving the SiteAdmin administration there.
SiteAdmin API is already a functional part of the platform but is still under development. This is a key difference from WordPress’s more mature API ecosystems—and we’re clear about it to avoid unnecessary comparisons.