Aleph

Aleph is OCCRP's investigative data platform. It indexes leaks, company registries, court records, sanctions lists and other public documents and lets you search across them, extract entities, and cross reference names against watchlists. The public instance at aleph.occrp.org holds hundreds of millions of documents; the software is open source, so you can run your own instance for your own document sets.

It's built for investigative journalists and works well for fraud and money laundering investigations.