A computer method and system dynamically provide consistency of Java application files. A processor executed routine is configured (e.g., instrumented as an agent) to intercept each class that is loaded into a subject Java application or JVM. The system computes a cyclic redundancy check (CRC) of the respective JAR file surrounding the loaded class. The system compares the computed CRC value to a CRC value of at least one other copy of the respective JAR file. Based on results of the comparison, the system determines consistency (e.g., same version) of the multiple copies of the respective JAR file used by the subject Java application. If the multiple copies of the respective JAR file are determined to be inconsistent, the system alerts the user and/or enables the application to abort. The comparative CRC value may be stored in a repository; and the step of comparing looks up the stored CRC value in the repository.