Citations API Response Viewer

It's a Messages API feature where you mark a document content block with citations: { enabled: true }. Instead of one plain text response, Claude splits its answer into multiple text blocks, and any block backed by a source document carries a citations array — each entry has the cited_text, which document it came from (document_index / document_title), and a location: a char_location (start_char_index/end_char_index) for plain text, a page_location (start_page_number/end_page_number) for PDFs, or a content_block_location (start_block_index/end_block_index) for custom content blocks.

The full Messages API response JSON, just its content array, or a single content block — this tool detects which one you gave it. The easiest way to get one is to log response.content (or the whole response) from a request where at least one document block had citations enabled, then paste that straight in.

The verifier slices your pasted document at the citation's start_char_index and end_char_index and compares that exact slice to cited_text. A mismatch almost always means you pasted a different version of the document than the one actually sent in the request — different whitespace, a re-exported copy, or an edited draft — not a bug in the Citations API itself. It's meant as a debugging aid for your own integration.