Local Cookies Explained

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Many years ago I wrote the first ever full explanation about what a “local cookie” is and how it can help Merchants on or considering using multiple networks. It’s been featured on many Affiliate forums and is the de-facto explanation in plan English as I can manage with a subject that is technical. Over the years I have seen many fancy attempts to reinvent this simple straight forward system and every one has been a massive and costly failure. So take it from me, read what I have to say, follow this advice and you will be setup to use “local cookies” in the simplest most straight forward and fair way available. Never trust the Network that says it can’t be done or doesn’t work, they are lying to you and have a vested interest in you not using another Network as they couldn’t stand seeing you make loads of sales via the competition as they found gaps in your Affiliate strategy that they couldn’t see. My advice to Merchants is always give Affiliates choice, be on at least 2 Networks, maybe 3 but 4 or more is just wasting your time. No matter how many you go with, just make sure you do “local cookies” right, as sadly very few Networks give the correct advice, instead they often say the only solution is to just use one network, them!

Increasingly as Merchants are signing up to more than one Affiliate Network to compare the services on offer. Local cookies have been the preferred method of eliminating multi-network tracking issues. They allow a Merchant to accurately know which network sent a sale/lead to them. When set-up correctly, the local cookie is a reliable way to ensure correct attributing of commission and avoidance of payment duplication.

I address some of the common misconceptions and explain some of the benefits of local cookies to you as a Merchant.

Multi-network tracking issues include:

  • How do I know what network sent me a sale/lead if it’s showing in both accounts at each network?
  • I have been paying out £1 a click on PPC and I noticed that some of my PPC sales are being credited to Affiliates, how do I know what one resulted in the final sale?
  • I had been told that Deep links wouldn’t work if I use local cookies?

Industry Standard

To address these issues the generally agreed ‘best method’, and one that’s been used for years by big Merchants who are paying to be on multi-platforms, not just affiliate networks but PPC, CPM, Portals and countless other places is to set a local cookie.

The local cookie, which is just a normal cookie, stores the name or reference to the network/advert which last referred the customer to the site. Your order/checkout systems can then read this local cookie and show the tracking code for that network or promotional campaign. A local cookie (when set-up correctly) will be as reliable as the network cookie and will mean you will be able to spend money on other campaigns such as PPC, CPM and so on while only ever paying commission to the source responsible for last referring the customer when they make the actual sale/lead.

A Little Respect

To succeed in Affiliate Marketing it is very important that you must always treat all sources of sales with the same respect and on a level playing field. For example just because you have paid for a search engine ad campaign doesn’t mean you should ignore setting a local cookie to track when an Affiliate sends you a customer. The same is true if you paid for PPC but a visitor sent via this doesn’t initially purchase but returns later via an Affiliate link. In this case the last refer (the Affiliate) should be the one set in your local cookie. You will have to write the script that sets and reads the cookie yourself, however we can assist you and perform full testing to ensure you have it set-up and are calling it correctly (and fairly). This will ensure Affiliates are paid correctly regardless of the network they are promoting you through. It will in turn build a relationship of trust and mutually benefit everyone as the Affiliate will be more inclined to promote you and to recommend you to other Affiliates. This set-up is really rather simple to do, your only obstacle might be if a network refuses to work with you to accomplish it, then you might want to reconsider you business relationship with them.

Deep Linking

The great thing is that deep links can continue to work even if you are directing all traffic to a script to set the local cookie before taking the visitor to the page on your site. As long as the Affiliate Network can include the deep link onto the query string of the URL then your script can set the cookie and then redirect to the deep link given on the query string. Or with Paid On Results, the Merchant can redirect the visitor back to us after setting the local cookie. We will then redirect the visitor again but this time to the deep link and not through any script which originally set the local cookie for the Merchant. NB (the URL used is a static URL meaning you the Merchant doesn’t have to pass along any extra values to it for the feature to work).

Here is a simple example of the style of URL that could be used when deep linking to a local cookies script.


You would simply set the local cookie to contain the network=XX value, and then redirect to merchant.com/product-123.html

A Solution For All

Using multiple networks needn’t be the preserve of big Merchants, it can be a choice for all. Not having a local cookie in place and then reversing sales will make you look amateur in the eyes of the Affiliates. Additionally it is unfair for them to have to suffer reversals because you didn’t implement this straightforward solution. I would recommend that you speak to your current network providers to see if they can advise you on what might need changed, if they say it can’t be done (probably because they don’t want you working with another Network) or refuse to help, give me a shout and I will explain it to you.

The alternative is to simply approve sales on all your networks even if they are duplicates, of course this is far from ideal for you as a Merchant and makes things easier for an Affiliate involved attempting fraud.

Check List

Some things you should check, before going live with your local cookie system. This is not an exhaustive list, just the main things, networks like Paid On Results carry out additional check above these, however these are the basics.

  • Your local cookie lasts exactly the same length as your Network cookie + 1 day.
  • You set and replace the last refereeing source of traffic as it hits your script, example Network 1 is replace by Network 2 when they send the same visitor via one of there Affiliates and vice versa.
  • You are applying the same rules to all forms of traffic your are monitoring this way such as your own PPC, if the Network sends someone who has already visited your site via your own PPC, the local cookie would be overwritten in favour of the Network and the same applies when someone who came to your site via the Network comes via your own PPC later.
  • You can not include direct domain type in traffic, SEO direct to your site, your own email newsletters; paid listing in other newsletter can use the local cookie system for tracking if you wish.
  • If you have no referrer in you local cookie, you must show all tracking codes for all Networks, this will catch any situation where the local cookie has failed such as when a user removes the local cookie from there system but still has the Network cookie planted on there machine, this doesn’t happen often but is also a back up for local cookie failure.
  • Regularly test your setup when you add or remove a referrer from it or when update your site design or checkout pages, you will be amazed at the number of Merchants that forgot to add the Networks tracking code in when they design a new site 🙂

I hope you find this article useful, feel free to link to it and use extracts from it, but please credit affiliatemarketingblog.co.uk as the source in any articles.

This Post Has 8 Comments

  1. Chris

    Having been introduced to local cookies a few years ago by Clarke it amazes me how this simple piece of scripting is so overlooked across our industry.

    Take the time to work out the benefits this can have for you and your affiliates. I probably say this too often, but like most great ideas it’s simple common sense (with a nifty bit of scripting thrown in).

  2. KowaJeff

    If I’m understanding this correctly, you would overwrite an affiliate cookie with a PPC cookie if the click on the PPC came later, correct? Isn’t this a violation of most network’s TOS?

  3. Clarke

    Hi KowaJeff, I don’t know any network where what I have said would be in violation of the TOS, least not in the UK. If you could maybe give examples I would like to check it over, as it could possibly be that via these Networks, Merchants don’t allow any Affiliates to bid on any PPC activity at all or have other rules on how the approve sales that they feel have been generated by another source.

    Basically what I am saying in my article is the last source = gets the sale, be it Affiliate or Merchants own non-affiliate activities, expect SEO or direct to site traffic. Many Merchants doing PPC or employing an Agency to do it are annoyed to find they are paying for both the PPC and the Affiliate activity and this is simply a fair way to make sure the correct person responsible for the sale is paid out. It is the same as if the PPC ad was an Affiliate one, the last referring source, was another Affiliate, or Merchants own campaign.

  4. KowaJeff

    I completely agree that Merchants need to consider the costs of paying an affiliate commission on a sale in which a PPC click followed the affiliate click; but I believe CJ for instance (and LinkShare as well) require that any sale that comes via an affiliate click — whether before or after any other source — must be attributed to that affiliate. Their revenue is attached to that click and they also need to “protect” their affiliates.

    This leads to a much larger discussion of commission structures and best business practices when running an affiliate program within a larger multi channel marketing environment. I just don’t think the big US networks want to get involved in that conversation because it would cause a huge disruption in their platform, their value proposition, and their bottom line. My company, KowaBunga, is an exception, as it has a platform that uses a local cookie to track all incoming links as well as storing every source of traffic one customer may have come through. But I’m not here to push my company, I’m really interested to see what everyone thinks of this issue.

  5. Clarke

    Hi KowaJeff, I agree there is definitely a need for a much larger discussion of commission structures and best business practices. I guess a blog post about this could definitely be of interest to people in the Industry. I have for example got a few post ideas lined up such as ways Affiliates are losing out on sales, scenarios when tracking fails and these I feel are important as they all play in to how Merchants should be looking at commission structures based on having a healthy understanding of what is actually going on.

    Just to add that in practice for the most part I have really only seen local cookies being used by Merchant more worried about multiple sales showing across Networks, very few of them actually have the tracking systems to know what is going on with there own other activates in great deal, most Merchants couldn’t tell you how many of there customer come via the Affiliate Channel later lead on to additional income for the Merchant that they don’t have to pay Affiliate or Networks for, at least this has been my experience.

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