Systems and methods for verifying interactions performed on content items are hereby provided. An interaction verifier encoded in a first portion of code of a content item can detect a first interaction event attributed to the content item. The interaction verifier can identify, via execution of a second portion of code of the content item, a registration of a function call to perform a predetermined action. The function call can be configured to be triggered in response to the application passing a second interaction event to the content item. The interaction verifier can determine that an amount of time between the first interaction event and the registration of the function call is less than a predetermined threshold. The interaction verifier can cause the application to perform the predetermined action in response to determining that the amount of time is less than the predetermined threshold.