9 Ways to Save Bandwidth on your RSS Feed

One of the things you will notice after you have published an rss feed is that it will consume a lot of the bandwidth. For example on my site Spendfish 18% of all requests are for RSS feeds. This is no wonder since feed readers may download your feed several times a day even if nothing has changed.

I've put together a list of ways you can save bandwidth and reduce the number of requests to your RSS feed (which also saves server resources).

1 - Use the ttl Tag

The ttl tag goes directly inside the channel tag in your RSS feed. It stands for time to live, and should hold the number of minutes a RSS reader should wait before requesting your feed again. Most blog software defaults this setting to 60, which means that your feed will be downloaded every hour by clients that obey this setting. We can increase this to 3 hours by adding the following:

<ttl>180</ttl>

Read more about ttl here

2 - Add a skipDays tag

The skipDays tag also goes inside the channel tag and should contain several child day tags. As you might guess this tells RSS readers to skip downloading your feed on the specified days. For example if you don't publish content on the weekends:

<skipDays>
  <day>Saturday</day>
  <day>Sunday</day>
</skipDays>

3 - Add a skipHours tag

Same idea as the skipDays tag, but allows you to specify which hours during the day your feed should not be downloaded. The hours are specified in 0-23 using GMT. For example since I'm in New York, and I typically don't post things to my blog very early in the morning I could add:

<skipHours>
  <hour>7</hour>
  <hour>8</hour>
</skipHours>

More info about skipHours and skipDays here.

4 - Support If-Modified-Since header

Many RSS readers and clients send an If-Modified-Since header in their request to your RSS feed. This is one of the ways clients make what's called a conditional HTTP GET, you can return a 304 Not Modified HTTP response code (and omit the request body) if the RSS feed has not changed since the date specified in the If-Modified-Since header. If the content has changed you simply return the normal 200 status code.

The header sent by the client might look something like this:

If-Modified-Since: Tue, 10 Jul 2007 21:19:55 GMT

Most clients will pass in the value you specify in the Last-Modified header, so you should make sure that header is being populated. More info here. ColdFusion If-Modified-Since example here.

5 - Support ETag and If-None-Match HTTP headers

The ETag header is a HTTP response header that you can send back in your RSS feed response. It stands for entity tag and should be a unique value representing the content, you could do a MD5 hash of your RSS feed content, or simply use a date time of the last change. Clients will send this back in a If-None-Match header, if this header contains your current ETag then you can return a 304 status code. More info about If-None-Match here.

6 - Don't send the request body on HTTP HEAD requests

Here's what HTTP 1.1 has to say about the HEAD method:

The HEAD method is identical to GET except that the server MUST NOT return a message-body in the response.

The HEAD method should only return HTTP headers, and no request body (so you don't need to return your entire RSS for these types of requests). You will find that several aggregators and readers will make HEAD requests for your feed (including MXNA), it's a simple way to save some bandwidth.

7 - Limit the number of items you publish

This one is kind of obvious, but it is a very easy way to save bandwidth in your rss feed. If you are publishing 15 items or articles in your feed, if you lower that to 10 you can save a good amount of bandwidth.

8 - Publish Partial Content feeds

Another obvious way to save bandwidth - don't publish full articles in your feed. By publishing just the first few sentences of content you can also save a good amount of bandwidth. Your readers may not be too happy about this one however.

9 - Use Gzip Compression

Configure your web server to return the contents using gzip compression

Do you have any other techniques that work? I considered adding Cache-Control, but I wonder if that would actually take away the savings you would get from a Conditional Get?

I have to thank Charlie Arehart for giving me the idea for this blog entry. After my Working with RSS in ColdFusion presentation at cfunited he suggested that I write a blog entry on ways to reduce the bandwidth consumption of your RSS feed. After doing the research for this entry I realize that this topic could the subject of an entire presentation!