Needle in a Haystack Generator
Build reproducible synthetic context with one inserted test sentence.
Processing stays in your browser. Creates deterministic filler for retrieval tests. Paragraph count is not a model token count; use your model tokenizer to measure the generated context.
How to use the needle in a haystack generator
Build reproducible synthetic context with one inserted test sentence. Complete the needle sentence, filler paragraphs (1–1000), insertion position (%) fields above, or upload a UTF-8 text file for needle sentence. Choose Run tool, review the output, then copy or download the result.
Example
50% inserts the needle halfway through the filler paragraphs.
Good to know
Creates deterministic filler for retrieval tests. Paragraph count is not a model token count; use your model tokenizer to measure the generated context.