> ## Documentation Index
> Fetch the complete documentation index at: https://docs.gateways.app/llms.txt
> Use this file to discover all available pages before exploring further.

# Runtime: Application servers

> Optional application server stack selection for Python, PHP, .NET, and Perl runtimes in the runtime configuration panel.

For some **language families** only, the configuration panel shows a second row: **Application server**. This is **not** a separate Create submenu—it appears **after** you select a **family** that has server options defined in the product.

## When it appears

**Application server** choices are shown only if the selected family has at least one option. In the console, built-in mappings include:

| Family     | Options (key → label)         |
| ---------- | ----------------------------- |
| **Python** | **Uvicorn**, **Gunicorn**     |
| **PHP**    | **PHP-FPM** (`php-fpm-caddy`) |
| **.NET**   | **Kestrel**                   |
| **Perl**   | **Starman**                   |

Families such as **Node.js**, **Go**, **Deno**, and **Bun** use the **version** dropdown only; they do **not** show this application-server row in the current UI (no entries in the internal `APP_SERVERS` map for those keys).

## Behavior

* Choosing a server sets **`applicationServer`** on the runtime resource (string key such as `uvicorn`, `gunicorn`).
* Help text under the row describes it as the application server for that **runtime family** (for example “Application server for Python runtime”).
* Logos for server types use the same icon set as elsewhere in the panel when available.

## API

Server stacks available per language can also be queried with **`GET /api/runtimes/servers?runtimeName=...`** (see **[Runtimes API](/api/28-runtimes)** in the bundled API docs). Use that for automation or to confirm options beyond what this guide lists.

[← Runtime overview](/gateways/resources/runtime) · [Families and versions](/gateways/resources/runtime/families-and-versions)