Edit PDF Metadata Online Edit PDF metadata.

Under the hood, this tool uses client-side JavaScript with React to handle file input and metadata editing. When a PDF file is dropped into the FileDropzone component, the handleFile function is triggered, which loads the PDF document using the pdf-lib library. The library's PDFDocument class is used to extract existing metadata, such as title, author, subject, and keywords, which are then pre-filled into the corresponding input fields. This process involves reading the PDF file as an array buffer and parsing its contents using pdf-lib's load method with the ignoreEncryption option set to true.

The tool's UI is built using React components, including InputWithHelp for metadata fields and a glass-card component for displaying file information. When the user updates metadata fields and clicks the Update Metadata button, the process function is called, which creates a new PDFDocument instance, sets the updated metadata using methods like setTitle, setAuthor, and setKeywords, and saves the changes to a new PDF file. The saved PDF is then converted to a blob and stored as an object URL using the URL.createObjectURL method.

The tool also uses React's useState hook to manage state variables like file, pageCount, processing, result, and error, which are updated accordingly during the file loading and metadata editing process. Additionally, the useCallback hook is used to memoize functions like handleFile, process, download, and reset, ensuring that they are not recreated unnecessarily during re-renders. The Clipboard API is not explicitly used in this implementation, but the tool does create a downloadable PDF file with updated metadata when the user clicks the download button. The UI is designed to be responsive, adapting to different screen sizes and devices using CSS classes like glass-card and sm:grid-cols-2.