أحسن الله إليكم A company wants me to extract data from their competitors' websites (according to their terms of service). But these data are primarily prices of e.g. food products but the products aren't necessarily guaranteed halal. Is that permissible?

If you only want to know the prices, then there is nothing that is forbidden, as long as you don't aid in something that is forbidden. For example, if he wants you to take these prices in order for him to do something that is forbidden (like to sell something that is forbidden), that would be an issue.