[Home](./index.md) > [@contract-case/case-definition-dsl](./case-definition-dsl.md) > [matchers](./case-definition-dsl.matchers.md) > [strings](./case-definition-dsl.matchers.strings.md) > [Base64Encoded](./case-definition-dsl.matchers.strings.base64encoded.md) > [(constructor)](./case-definition-dsl.matchers.strings.base64encoded._constructor_.md) ## matchers.strings.Base64Encoded.(constructor) Transformation matcher that matches a base64 encoded version of the given string or string matcher WARNING: Since many strings are accidentally decodable as base64, this matcher is best combined with a more restrictive string matcher (eg `StringifiedJson`). **Signature:** ```typescript constructor(child: AnyMatcherOrData); ``` ## Parameters

Parameter	Type	Description
child	AnyMatcherOrData	The string or string matcher that would match the decoded string