---
title: PerformanceTiming.responseStart
slug: Web/API/PerformanceTiming/responseStart
tags:
  - API
  - Backwards compatibility
  - Deprecated
  - Navigation Timing
  - PerformanceTiming
  - Property
  - Read-only
  - Reference
  - legacy
browser-compat: api.PerformanceTiming.responseStart
---
{{APIRef("Navigation Timing")}}{{Deprecated_Header}}

> **Warning:** This interface of this property is deprecated in the [Navigation Timing Level 2 specification](https://w3c.github.io/navigation-timing/#obsolete). Please use the {{domxref("PerformanceNavigationTiming")}}
> interface instead.

The legacy
**`PerformanceTiming.responseStart`**
read-only property returns an `unsigned long long` representing the moment in
time (in milliseconds since the UNIX epoch) when the browser received the first byte of
the response from the server, cache, or local resource.

## Syntax

```js
time = performanceTiming.responseStart;
```

## Specifications

This feature is no longer on track to become a standard, as the [Navigation Timing specification](https://w3c.github.io/navigation-timing/#obsolete) has marked it as deprecated.
Use the {{domxref("PerformanceNavigationTiming")}} interface instead.

## Browser compatibility

{{Compat}}

## See also

- The {{domxref("PerformanceTiming")}} interface it belongs to.
