[Launch options](https://cdpfleet.com/docs/options)

# `ff_version`

Firefox major version to claim in the fingerprint.

**Use it for:** Sites that only support certain Firefox versions, or reproducing what an older Firefox user sees.

**Browsers:** [Camoufox](https://cdpfleet.com/docs/browsers/camoufox#opt-ff_version).

## Details

-   **Type:** `number`
-   **Default:** the real Firefox major
-   **Example:** `{"ff_version":135}`

Changes the version the fingerprint reports (user agent etc.), not the actual browser build. To run an older build, use `version`.

A reported version that differs from the real engine is detectable.

## Used in

-   [Camoufox reporting an older Firefox](https://cdpfleet.com/docs/examples#camoufox-ff-version)

All options: [launch options](https://cdpfleet.com/docs/options).

---
Source: https://cdpfleet.com/docs/options/ff_version · Markdown: https://cdpfleet.com/docs/options/ff_version.md · All docs for AI tools: https://cdpfleet.com/llms.txt