ClickTale, a startup that helps companies see exactly what visitors are doing when they visit a website, says it’s seeing strong growth despite the downturn, with more than 500 paying customers and 500 percent revenue growth in the past year. Chief executive Tal Schwartz says ClickTale’s analytics data becomes even more valuable in the downturn as companies take a close look at their bottom lines — and he shared some numbers to back that up.

(Disclosure: Robert Goldberg, one of VentureBeat’s advisers, is a ClickTale investor.)

The Israel-based company focuses on providing super-detailed information about user behavior within each web page, such as videos of site visits and heat maps displaying where people spend the most time. (An Israel-based competitor called NuConomy is more focused on data showing the relationship between a site and user behavior.) ClickTale’s latest product lets you track visitors through email — when you promote your site via email, each message has a customized tag. So not only can you see the behavior for each visit, you can connect that behavior to a specific user or a specific campaign.

To illustrate ClickTale’s payoff, Schwartz sent me some numbers from event listings site In the five weeks after adding ClickTale, Skiddle’s average bookings per week increased about 3.5 times. (See graph below; I’ve removed the numbers at Skiddle’s request, but it covers a roughly 1-year period.)

ClickTale has raised an undisclosed amount of funding from angel investors and venture firm YL Ventures. Schwartz says he’s talking to firms for a potential second round but isn’t in any hurry to make a deal.