Ground Claude's responses in your source documents. Citations return the exact passages that support each claim, so you can verify answers and surface sources to your users.
Claude can provide detailed citations when answering questions about documents, helping you track and verify the sources behind each response.
Set citations.enabled=true on each of your documents. Currently, citations must be enabled on all or none of the documents within a request.
Only text citations are currently supported. Image citations are not yet possible.
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Documents get processed
Document contents are "chunked" to define the minimum granularity of possible citations. For example, sentence chunking lets Claude cite a single sentence or chain together multiple consecutive sentences to cite a paragraph or longer passage.
For PDFs: Text is extracted as described in PDF support and content is chunked into sentences. Citing images from PDFs is not currently supported.
For plain text documents: Content is chunked into sentences that can be cited from.
For custom content documents: Your provided content blocks are used as-is and no further chunking is done.
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Claude provides cited response
Responses may now include multiple text blocks where each text block can contain a claim that Claude is making and a list of citations that support the claim.
Citations reference specific locations in source documents. The format of these citations is dependent on the type of document being cited from.
For PDFs: Citations include the page number range (1-indexed).
For plain text documents: Citations include the character index range (0-indexed).
For custom content documents: Citations include the content block index range (0-indexed) corresponding to the original content list provided.
Document indices are provided to indicate the reference source and are 0-indexed according to the list of all documents in your original request.