Skip to main contentğŸ¦œï¸�ğŸ”— LangChainDocsUse casesIntegrationsAPILangSmithJS/TS DocsCTRLKGet startedIntroductionInstallationQuickstartModulesModel I/â€‹OData connectionChainsMemoryAgentsCallbacksModulesGuidesEvaluationString EvaluatorsEvaluating Custom CriteriaCustom String EvaluatorEmbedding DistanceQA CorrectnessString DistanceComparison EvaluatorsTrajectory EvaluatorsExamplesDebuggingDeploymentLangSmithModel ComparisonEcosystemAdditional resourcesGuidesEvaluationString EvaluatorsCustom String EvaluatorCustom String EvaluatorYou can make your own custom string evaluators by inheriting from the StringEvaluator class and implementing the _evaluate_strings (and _aevaluate_strings for async support) methods.In this example, you will create a perplexity evaluator using the HuggingFace evaluate library.