More than 1,400 police were involved in the raids in 15 of Germany's 16 states and in neighbouring Austria and Poland on Tuesday, said prosecutors in Bamberg, in the southern state of Bavaria.
Police said they found weapons, drugs, computers, around €50,000 in cash, cryptocurrency and more than 300 terabytes of data in the raids on 232 sites.
The raids targeted users of crimenetwork.co, an “underground economy forum that trades almost exclusively in illegal goods and services” according to the Frankfurt prosecutors.
These include drugs and narcotics, counterfeit money, data including credit card information, forged documents and cash, malware and hacker tools including botnets.
Then aged 26, the administrator of the forum was arrested on entering Germany in May 2019 on a separate charge and the site was seized by police.
Authorities across several German states have been investigating users of the platform since August.