CourtListener is a free, non-profit legal research platform run by the Free Law Project, offering searchable access to millions of court opinions across federal and state jurisdictions, updated continuously since the project began collecting case law in 2009. Beyond opinions, it covers oral arguments, judge biographical data, and financial disclosures, all searchable through a public API.
Its RECAP Archive is the standout feature for cost-conscious researchers: a free browser extension captures documents purchased from PACER and adds them to a shared, permanently public archive, so anyone searching the same case later can access previously purchased filings at no cost. Because it's donor and volunteer supported rather than commercial, CourtListener trades some of the polish of paid platforms for genuinely free, open access to primary legal materials.
Researchers who need paid depth beyond CourtListener's free tier typically look to Lexis+ or Harvey AI.