<![CDATA[Manual, ledger-based recording still dominates library management in many pesantren, including at Pondok Pesantren Darunnajah Jakarta, where borrowing, returning, visitor registration, and collection management remain error-prone, hard to trace, and vulnerable to data loss. This study designs and develops a web-based library information system that digitizes these processes, using React JS for the front end, Node.js with Express JS for the back end, and a MySQL database managed through phpMyAdmin, with the RESTful API documented in Swagger UI. Where prior pesantren and school library systems were built mainly on PHP/Laravel/Bootstrap stacks, this study contributes a full-stack JavaScript implementation developed under the Waterfall model and validated through both black box testing and User Acceptance Testing (UAT). All eleven functional areas tested passed black box testing, and a Likert-scale UAT completed by 18 respondents (12 students, 3 teachers, 3 library staff) across 17 indicators produced a total score of 1,360 out of a maximum 1,700 (80.00%), placing the system in the “Good” category under Sugiyono's interpretation scale. These results indicate that the system operates in accordance with its functional specification and was well received by the users who evaluated it, because the sample was small and drawn from a single institution, the finding is best read as an indicative rather than a generalizable measure of acceptance.]]>
