> For the complete documentation index, see [llms.txt](https://developers.weglot.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developers.weglot.com/cms/wordpress/filters/host-and-url-hooks.md).

# Host & URL Hooks

WordPress Filters relating to the host Weglot uses to build URLs, hreflang tags and the language switcher

Weglot needs to know the **public host** of the current request to build the language switcher links, the `hreflang` tags, and to decide whether a link is internal and should be rewritten with the language prefix.

By default it reads the `Host` header sent by the browser, which is correct on the vast majority of sites. You do not need any of the filters on this page unless your site sits behind a **reverse proxy**.

#### When you need these filters

Behind a reverse proxy (a CDN, a load balancer, or a hosting setup that fronts your origin with an internal domain), the origin server does not receive the public domain in the `Host` header — it receives its own internal hostname. The public domain is carried by the `X-Forwarded-Host` header instead.

When that happens, WordPress keeps working normally, because `home`, `siteurl` and the canonical URLs are stored in the database. But Weglot resolves the host from the request, so you see:

* language switcher links pointing to the internal domain,
* `hreflang` tags pointing to the internal domain,
* internal absolute links not getting the language prefix.

A typical symptom is a page whose canonical URL is right while the switcher and `hreflang` are wrong.

{% hint style="warning" %}
On a WordPress multisite, do not try to fix this by editing the `domain` column of the `wp_blogs` table. WordPress uses that value to resolve which site the incoming request belongs to, so changing it breaks site resolution and causes a redirect loop.
{% endhint %}

#### weglot\_use\_forwarded\_host

Tells Weglot to read the public host from the `X-Forwarded-Host` header instead of `Host`.

{% hint style="info" %}
Available since Weglot 6.3.
{% endhint %}

| Argument              | Type | Description                                  |
| --------------------- | ---- | -------------------------------------------- |
| $use\_forwarded\_host | bool | `false` by default. Return `true` to opt in. |

**Use case**

Your site is served on `example.com`, but the origin receives an internal hostname and the public domain arrives in `X-Forwarded-Host`.

```php
<?php

add_filter( 'weglot_use_forwarded_host', '__return_true' );
```

If the header is absent on a given request, Weglot falls back to the `Host` header, so the filter is safe to leave enabled.

When several proxies are chained, `X-Forwarded-Host` can contain a comma-separated list such as `example.com, internal.host`. Weglot keeps the first entry, which is the host the visitor actually requested.

{% hint style="danger" %}
`X-Forwarded-Host` is a header sent by the client. Only enable this filter if your proxy **overwrites** it on every incoming request. If the proxy forwards a client-supplied value untouched, a visitor can inject any domain — and if your site uses a page cache, the poisoned links can then be served to everyone else.
{% endhint %}

#### weglot\_server\_host

Forces the host directly, whatever the request headers contain. Use it when no header carries the public domain, or when you prefer not to trust `X-Forwarded-Host`.

{% hint style="info" %}
Available since Weglot 6.3.
{% endhint %}

| Argument | Type   | Description                                |
| -------- | ------ | ------------------------------------------ |
| $host    | string | The host resolved from the request headers |

**Use case**

```php
<?php

add_filter( 'weglot_server_host', function ( $host ) {
    return 'example.com';
} );
```

Return the host name only — no scheme, no trailing slash, no path.

This filter is applied last, so it overrides `weglot_use_forwarded_host`. It is the most reliable option when your public domain is a fixed, known value.

#### weglot\_check\_link\_server\_host

Overrides the host used for one specific decision: whether an absolute link found in the page is internal (and must be rewritten with the language prefix) or external (and must be left alone).

This filter is not new — it has existed for several versions and was simply undocumented until now.

| Argument      | Type   | Description                               |
| ------------- | ------ | ----------------------------------------- |
| $server\_host | string | The host resolved for the current request |

In most cases `weglot_server_host` is what you want, since it covers link rewriting along with the switcher and the `hreflang` tags. Reach for `weglot_check_link_server_host` only when you need link rewriting to use a different host from the rest of the page.

```php
<?php

add_filter( 'weglot_check_link_server_host', function ( $server_host ) {
    return 'example.com';
} );
```