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# `postMessage`

Connect to a wallet hosted on another domain from anywhere on the web. Communication happens over the [uRPC window](https://github.com/tempoxyz/urpc/blob/main/specs/transport-window.md) transport.

## Usage

```ts twoslash
import { Provider } from 'accounts'
import { postMessage } from 'accounts/postMessage'

const provider = Provider.create({
  adapter: postMessage({
    host: 'https://wallet.example/post-message',
    name: 'Example Wallet',
    rdns: 'com.example.wallet',
  }),
})
```

## tempoWallet

To connect to the Tempo Wallet, use the preconfigured [`tempoWallet`](/docs/api/postMessage#tempowallet) below.

````ts twoslash
import { Provider, tempoWallet } from 'accounts'

const provider = Provider.create({
  adapter: tempoWallet(),
})



## Parameters

### host

- **Type:** `string`
- **Required by:** `postMessage`

URL of the wallet's post-message page. The adapter tags the URL with your app's origin — so the wallet can pin its responses before the first frame arrives — and the mount mode, so approvals render matching chrome.

### mount

- **Type:** `Mount.Factory`
- **Optional**

Where the wallet page lives and how it surfaces for requests. Defaults to `Mount.auto()` — an overlay iframe, or a popup where iframes can't work.

### name

- **Type:** `string`
- **Required by:** `postMessage`

Provider display name.

### rdns

- **Type:** `string`
- **Required by:** `postMessage`

Reverse-DNS provider identifier.


## Mounts

The mount decides where the wallet page lives and how it surfaces for requests. By default the adapter picks for you: an overlay iframe, falling back to a popup in insecure contexts or when the browser lacks IntersectionObserver v2 (the wallet can't run its occlusion defense). On Safari, account requests use a temporary popup because Safari rejects WebAuthn creation inside cross-origin iframes. If the wallet detects its iframe is occluded mid-session, it asks to continue in a popup and the adapter remounts there, replaying the request.

A popup opens for each burst of requests and closes once the last one settles, so a request sent after that opens and loads the wallet again. To sign in and sign a message or authorize an access key with one approval, pass `personalSign` or `authorizeAccessKey` in the [`wallet_connect`](/docs/rpc/wallet_connect) capabilities instead of sending a second request.

Pass a mount to pin one explicitly:

```ts twoslash
import { popup, postMessage } from 'accounts/postMessage'

const adapter = postMessage({
  host: 'https://wallet.example/post-message',
  mount: popup({ size: { height: 440, width: 360 } }),
  name: 'Example Wallet',
  rdns: 'com.example.wallet',
})
````