mitmproxy/doc-src/features/anticache.html

When the __anticache__ option is passed to mitmproxy, it removes headers
(__if-none-match__ and __if-modified-since__) that might elicit a
304-not-modified response from the server. This is useful when you want to make
sure you capture an HTTP exchange in its totality. It's also often used during
[client replay](@!urlTo("clientreplay.html")!@), when you want to make sure the
server responds with complete data.

<table class="table">
    <tbody>
        <tr>
            <th width="20%">command-line</th> <td>--anticache</td>
        </tr>
        <tr>
            <th>mitmproxy shortcut</th> <td><b>o</b> then <b>a</b></td>
        </tr>
    </tbody>
</table>