I've looked at these three CRM systems for some very simple lead management, they have the usual REST get info out, put info in data sync api, some have colour changing stuff but aside from that its seems impossible to integrate.
Take HighRiseHQ or ZohoCRM, all I want to do is add a button to the page that does an ajax post into my company system. If they give just one line, just one measly line in header, I can inject a script src="myurl/customise-zoho-crm.js" which manipulate the dom on ready, pull a few bits of info needed, injects a button and does ajax on hit. But no hosted CRM I can see allows this, unless you hit ms crm or salesforce..
I thought about greasemonkey as only 5 users, but its feel so dirty, but then to get basic contact/lead management is waste of my dev time. Due to sales calcs etc.. it does need to tie (or post into my backend system).. Any ideas?