Authority
Checker.

Courts in the United Kingdom, the United States and Germany are now sanctioning lawyers who cite cases that do not exist. Paste a skeleton, opinion or advice, and this tool confirms each authority is real and that its name matches its citation, against official sources.

Read this first. This tab confirms that a case exists and that its name matches its citation, and tells you what it is about. It does not tell you whether a case is still good law. Always open the linked official record. A green result means the case is real, not that it wins your point.
UK, US and (best effort) German citations. Nothing is stored.

Sources: Find Case Law (The National Archives, UK) and CourtListener / Free Law Project (US). German lookups link to openJur and rechtsprechung-im-internet.de for manual confirmation.