Text matcher

The Text Matcher evaluator examines the textual content of your LLM’s response to check for specific patterns, keywords, or regex matches. Use it to enforce content requirements, detect unwanted text, or validate response format — all without writing code.

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Set up the Text Matcher evaluator

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Examples

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Find SEO-oriented keywords

Use contains-all or contains-any to ensure responses include target keywords:

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Ensure the response begins with a specific phrase

Use starts-with to enforce a consistent response opening:

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Ensure the response does not contain personal information

Use not-contains-any to detect and flag responses that leak sensitive data:

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Validate format with regex

Use regex to enforce structural patterns (e.g., lowercase letters and numbers only):

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When to use

• Keyword enforcement — Ensure required terms or phrases appear in responses (SEO, compliance, branding).
• Content safety — Block responses containing banned words, personal information, or inappropriate content.
• Format validation — Check that responses follow a specific format (e.g., starts with a greeting, ends with a call to action).
• Simple pattern checks — Validate output structure with regex (email patterns, phone numbers, structured IDs).

For complex multi-step validation, consider the JavaScript evaluator. For qualitative assessment, use LLM-as-a-Judge.

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Next steps