# Client API

Build a customer-facing chat on an API inbox, from the customer's own device, with no secret.


```text
https://desk.texadesk.com/public/api/v1/inboxes/{inbox_identifier}
```

The Client API is what a chat on the customer's device calls: it needs no key. It knows the inbox
by its **inbox identifier** (the API inbox's Configuration tab) and the customer by the **contact
identifier** returned when you create the contact.

The contact identifier is that customer's key to their conversations: keep it on their device, or
behind their sign-in. Turn on the inbox's identity validation so a contact for one of your users is
made only with an `identifier_hash` your server signed.

Walkthrough: [bring your own channel](/desk/api-channel).