A web based user friendly document encryption application software was developed as a better cryptographic online system used in securing important tertiary institutions’ documents such as students' Official Grade Report (OGR) sheets, computed and approved results, transcripts, examination and test question papers, Senate/Council documents and any other sensitive or important document needed to be secured from unauthorized users. It is a known fact that problems like unsecured information, information misuse, tampering of sensitive documents by unauthorized persons, stress of hiding sensitive documents from unauthorized persons and locating hidden sensitive documents exist in any system/unit where proper data security mechanism is not in place. In this research work, an online cryptographic system was designed, using Advanced Encryption Standard (AES) algorithm, to secure important documents. The Analysis and Design of this system followed the Structured System Analysis and Design Methodology (SSADM) using web tools. The output of the software shows that the application can encrypt files and save in the database and can only be decrypted using a cipher key automatically generated by the system. With this software, sensitive information can be easily accessed without stress or fear and it has created a more reliable and safer platform to secure such sensitive documents other than the primitive method of using username and password.