Optimizing for different crawlers - PHP power in full effect

[z01d]

I love PHP for what it can do with plain old HTML. I am thinking of making a script that would output slightly different versions of the page to different crawlers, as identified by User Agent information.
Have anyone actually tried this?

Thank you for sharing.
z01d

[ChrisRC]

I have tried it - it's perfectly possible and there are good reasons to do it... but there are also bad reasons to do it and some search engines will therefore penalize you for "cloaking".

[z01d]

Thank you Chris.
What are the things to avoid? My intent is to offer basically the same version of the page to everyone, but perhaps with slightly different keyword ratios and placement to please different SE algos (i.e. i've read that Yahoo is more tolerant to high keyword density than google). I am not going to brazenly spam SE under the disguise, the risks are too high, but I would like to have an option to optimize for each separate SE.
Any advise you may share?

z01d

[ChrisRC]

I suggest posting to the Search Engine forum for the latest opinions on this.

Although I said there are good *reasons* for doing this, my understanding is that there isn't a safe *way* to do it. Some bots go out with different IPs and UAs specifically to identify sites that appear to be different at all and penalize those that are.

In theory, the content you show your human visitors is the best criterea for the bot to analyse and rank search results - so any attempt to influence the bot with tailored content is regarded as cheating.

[oceanmajk]

I have done something similar in the past, using the latest lists of IPs and user agents for the different crawlers and adapting my site fore each. It's a lot of work, and could still be considered cloaking in a way. If the site your visitor sees is different then how the search engine sees it, you could get banned. I simply changed some background stuff, not much noticeable to the visitors. I stopped doing what i was doing mainly because it was a lot of work to tweak the site for all the different spiders, even though i wrote a lot of custom scripts to maintain it automatically, but also couldn't afford to be black listed.

Maybe one way though would somehow show the visitor the same version the search engine sees depending on the referrer? Could be pretty slick. :-)

[z01d]

Thanks for your responses, guys.
I think I am going to abondon the idea. Too much work and too risky endeavor. Better have a different domain for each SE.

z01d