[Home](./index.md) > [@firebase/auth](./auth.md) > [ApplicationVerifier](./auth.applicationverifier.md) ## ApplicationVerifier interface A verifier for domain verification and abuse prevention. Signature: ```typescript export interface ApplicationVerifier ``` ## Remarks Currently, the only implementation is [RecaptchaVerifier](./auth.recaptchaverifier.md). ## Properties | Property | Type | Description | | --- | --- | --- | | [type](./auth.applicationverifier.type.md) | string | Identifies the type of application verifier (e.g. "recaptcha"). | ## Methods | Method | Description | | --- | --- | | [verify()](./auth.applicationverifier.verify.md) | Executes the verification process. |