Show HN: Check if any of the $656M in unclaimed royalties at The MLC is yours

The MLC (Mechanical Licensing Collective) is holding approximately $656 million in unclaimed mechanical royalties for musicians whose recordings haven't been properly registered or matched to their works in its database. A new tool called Blackbox Checker allows artists to search their music on Spotify, Apple, and other platforms to identify which of their recordings are unregistered or have unclaimed shares, and estimate how much money they're losing. Starting in early 2027, unmatched royalties will be distributed by market share among already-registered publishers, so artists need to claim and register their works now to protect future payments.