The screener uses a large data supplier, the name of which we are not allowed to mention due to contractual reasons.
We use the screener to invest our own money (that is how it started) and thus have a big incentive make sure the data is correct and all ratios are correctly calculated. It is thus not just a product we sell, we have a strong incentive for the screener to be up to date and correct.
The screener is updated daily with the previous day's closing prices (including financial results).
We have had very few problems with the data in the past, mainly definition changes, that were corrected very quickly.
We also have a very active community of users that point out inconsistencies quickly which we correct as soon as possible.