Is the cancellation button mandatory for all websites?

No, not for every website. The requirement under § 312k BGB applies only to businesses that establish ongoing contractual relationships with consumers in Germany through the internet — that is, contracts that automatically renew or continue over time, such as streaming subscriptions, gym memberships signed up online, magazine subscriptions or dating platforms. Pure B2B contracts between businesses don't apply, nor do one-off purchases without continuing services. However, anyone offering consumers a contract that can be concluded online and runs over time must provide a clearly visible cancellation button from 1 July 2022 onwards — regardless of company size or industry.