This research aims to develop a letter management application at the City of Pagar Alam Health Office in order to assist in managing data on incoming and outgoing mails which have become more organized by utilizing existing technology. The process of recording letters that have been running so far is still using conventional methods, namely by recording incoming and outgoing letters from the ledger and then storing sheets of letter paper as archival documents. Making this letter management application using PHP programming and MySQLi database and using the Codeigniter framework and also the system development method used is the waterfall method, namely by developing analysis, design, coding, and testing. System testing is carried out using the blackbox testing method by asking users questions or responses that are approved and in accordance with expectations. The results of this study consist of a management application letter at the City of Pagar Alam Health Office that can help and manage incoming and outgoing letters more effectively and efficiently.