Daniel Korell posted a comment on Facebook after he scanned a promo label to get information about ‘designing your own label’, but was directed to German porn site Fundorado.
"Your ketchup really isn't for under-age people," Korell wrote on the social media site.
"Even if the bottle was a leftover, it's still in lots of households.
"It's incomprehensible that you didn't reserve the domain [web address] for one or two years. It really doesn't cost the Earth."
The Heinz link had expired
The incident occurred after Heinz ran a promotion between 2012 and 2014, and the link expired this year.
Fundorado then registered the web address for itself, and the site once owned by Heinz was replaced with porn.
In response to Korrell’s message Heinz admitted the mistake and said: “We really regret the event and we're happy to take your suggestions for how we implement future campaigns onboard."
The company said it would let Korell create his own label and send him a free bottle printed with is design.