> For the complete documentation index, see [llms.txt](https://developers.oxylabs.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developers.oxylabs.io/products/agent-browser/engine-and-fingerprints.md).

# Engine & Fingerprints

Choose the browser engine and the operating system fingerprint for your Oxylabs Agent Browser sessions.

Agent Browser lets you select which browser engine runs your session and which fingerprint profile it presents to websites. Both are set with query parameters in your connection string:

```bash
wss://USER:PASS@hb.oxylabs.io?p_src=oxybrowser&p_fp_tag=oxyfp_mac_optimized
```

### Browser engine

<table><thead><tr><th width="97">Parameter</th><th width="463.5">Description</th><th width="74">Type</th></tr></thead><tbody><tr><td><code>p_src</code></td><td>Browser engine. Set to <code>oxybrowser</code> to use the proprietary browser engine, available for all accounts. If omitted, the standard Chromium engine is used.</td><td>string</td></tr></tbody></table>

### Fingerprint profiles

Use the `p_fp_tag` parameter to select a fingerprint profile:

<table><thead><tr><th width="192">Value</th><th>Description</th></tr></thead><tbody><tr><td><code>oxyfp_win</code> <em>(default)</em></td><td>Windows fingerprints. Applied automatically if <code>p_fp_tag</code> is omitted.</td></tr><tr><td><code>oxyfp_mac</code></td><td>Standard macOS fingerprints for general scraping.</td></tr><tr><td><code>oxyfp_mac_optimized</code></td><td>macOS fingerprints tuned for hard-to-access targets. Use only with <code>p_src=oxybrowser</code>.</td></tr><tr><td><code>oxyfp_win_v1</code></td><td>Legacy Windows profile.</td></tr></tbody></table>

{% hint style="info" %}
To always use the latest Windows fingerprints, omit `p_fp_tag` instead of setting `oxyfp_win_v1`.
{% endhint %}

### Troubleshooting

Access difficulty differs between targets, so the best combination can vary. For protected targets, start with `p_src=oxybrowser` and `p_fp_tag=oxyfp_mac_optimized`. If you still can't access them, experiment with other combinations:

* Switch between Windows and macOS profiles.
* Switch between the standard and the proprietary browser engine.
* Combine them with geo-location and device type adjustments.


---

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