In Düsseldorf, renters now have a quick way to check if their rent hike is legal. The local tenants association launched an online tool called “Mietwucher melden!”

Residents simply enter details from their landlord’s rent increase letter. Within ten minutes, the tool checks whether the hike exceeds legal thresholds and flags any violations.

Düsseldorf law allows new rents to be just 10% above the local average. Anything over 20% is seen as overcharging, while hikes above 50% may qualify as criminal rent gouging.

The tool also works for shared flats and helps renters reclaim overpaid amounts. If the rent is unlawful, users can file a complaint directly with the city.

While praised by tenants, the local association criticises city officials for slow enforcement. However, Düsseldorf’s model is spreading. Cities like Freiburg and Hamburg have introduced similar systems.

Other countries offer their own tools. Tenants in Sweden, France, and Austria can access public rent databases to check average prices in their areas.

With rising housing costs across Europe, Düsseldorf’s tool offers renters a fast, practical way to push back—and it’s catching on.

Photo: Daniel Foster via flickr