Leaked document reveals Anthropic’s banned and trusted Claude training sources

A leaked internal document has exposed the data sources used to fine-tune Claude, Anthropic’s AI assistant, revealing which websites were trusted or banned during the model’s training process. The spreadsheet, created by third-party contractor Surge AI and accidentally left in a public Google Drive folder, raises serious questions about data governance and transparency in AI development at a time when companies face increasing scrutiny over copyright and licensing issues.

What the leak revealed: The document contained over 120 “whitelisted” websites that contractors could use as trusted sources, alongside 50+ “blacklisted” sites they were instructed to avoid.

• Approved sources included prestigious institutions like Harvard.edu, Bloomberg, Mayo Clinic, and the National Institutes of Health (NIH).
• Banned sites featured major publishers and platforms including The New York Times, Reddit, The Wall Street Journal, Stanford University, and Wiley.com.
• The restrictions likely stem from licensing or copyright concerns, particularly notable given Reddit’s recent lawsuit against Anthropic over alleged data misuse.

Why this matters: While the data was used for fine-tuning rather than pre-training, legal experts warn that courts may not distinguish between these processes when evaluating copyright violations.

• The leak highlights growing vulnerabilities in the AI ecosystem as companies increasingly rely on third-party firms for human-supervised training.
• With Anthropic valued at over $60 billion and Claude competing directly with ChatGPT, every misstep invites heightened scrutiny.
• This incident follows similar data breaches at other AI vendors like Scale AI, suggesting systemic security issues across the industry.

The bigger picture: The revelation exposes how behind-the-scenes decisions by third-party vendors can influence the quality, accuracy, and ethical grounding of AI responses that millions of users rely on daily.

• Surge AI quickly removed the document after Business Insider reported the leak, while Anthropic claimed no knowledge of the list.
• The incident underscores the lack of transparency in AI training processes, even for top-tier models like Claude.
• As AI becomes more embedded in everyday tools, trust increasingly depends on companies’ willingness to be transparent about their data sources and training methodologies.

What it means for users: AI chatbot responses are deeply tied to the data sources selected during training, and inconsistent standards or unclear sourcing can introduce bias and accountability issues into the AI systems people use every day.