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

# Browser Profiles

> Understand browser profiles and operating system emulation.

## What are browser profiles?

Browser profiles define the network profile labels that `wreq-js` sends to the native layer. Profiles can influence behavior such as:

1. TLS handshake preferences
2. HTTP protocol behavior
3. Default request headers
4. Platform-specific header values

Final wire behavior is determined by the native engine and may vary by profile and runtime.

## Available browsers

wreq-js profile families include:

1. Chrome
2. Firefox
3. Safari
4. Edge
5. Opera
6. OkHttp

## Listing profiles

```typescript theme={null}
import { getProfiles } from 'wreq-js';

const profiles = getProfiles();
console.log(profiles);
// ['chrome_142', 'chrome_141', 'firefox_139', 'safari_18', ...]
```

## Using a profile

Specify the `browser` option in your fetch call:

```typescript theme={null}
import { fetch } from 'wreq-js';

const response = await fetch('https://example.com', {
  browser: 'chrome_142',
});
```

## Family aliases

Instead of a concrete profile you can pass a family alias, which resolves to the newest
profile in that family:

```typescript theme={null}
import { fetch, resolveProfile } from 'wreq-js';

const response = await fetch('https://example.com', {
  browser: 'firefox',
});

resolveProfile('firefox'); // 'firefox_149'
```

Available aliases: `chrome`, `firefox`, `safari`, `edge`, `opera`, `okhttp`,
`firefox_private`, `firefox_android`, `safari_ios`, `safari_ipad`.

Families are matched exactly, so `safari` resolves to the newest desktop Safari and never
to an iOS or iPad profile. Those have their own aliases.

<Warning>
  An alias resolves to the newest profile shipped with the version of `wreq-js` you have
  installed, so upgrading the library changes the fingerprint an alias produces. That is the
  point of using one, but it does mean a `wreq-js` upgrade can change how a target responds
  to you without any change in your own code.

  Pin a concrete profile when you need a fingerprint that never moves, and use
  `resolveProfile()` to record which one an alias picked.
</Warning>

The default `browser` is the `chrome` alias, so requests that do not set `browser` track
the newest Chrome profile rather than a pinned version that goes stale over time.

## Operating systems

Different operating systems have different header values and behaviors. Use the `os` option to emulate a specific platform:

```typescript theme={null}
import { getOperatingSystems } from 'wreq-js';

console.log(getOperatingSystems());
// ['windows', 'macos', 'linux', 'android', 'ios']
```

### Example: Windows Chrome

```typescript theme={null}
const response = await fetch('https://example.com', {
  browser: 'chrome_142',
  os: 'windows',
});
```

### Example: iOS Safari

```typescript theme={null}
const response = await fetch('https://example.com', {
  browser: 'safari_18',
  os: 'ios',
});
```

## Profile updates

Profile labels are sourced from the native layer and can evolve with upstream updates.

<Tip>
  Use a recent version of `wreq-js` if you want the latest profile set.
</Tip>

## Custom headers

By default, browser emulation headers are automatically added. To use only your custom headers:

```typescript theme={null}
const response = await fetch('https://api.example.com', {
  browser: 'chrome_142',
  headers: {
    'Accept': '*/*',
    'User-Agent': 'CustomBot/1.0',
  },
  disableDefaultHeaders: true,
});
```