diff -r fd87490429aa -r 2a99fcb283ee src/Pure/Admin/component_pdfjs.scala
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/Pure/Admin/component_pdfjs.scala	Tue Mar 07 22:54:44 2023 +0100
@@ -0,0 +1,96 @@
+/*  Title:      Pure/Admin/component_pdfjs.scala
+    Author:     Makarius
+
+Build Isabelle component for Mozilla PDF.js.
+
+See also:
+
+  - https://github.com/mozilla/pdf.js
+  - https://github.com/mozilla/pdf.js/releases
+  - https://github.com/mozilla/pdf.js/wiki/Setup-PDF.js-in-a-website
+*/
+
+package isabelle
+
+
+object Component_PDFjs {
+  /* build pdfjs component */
+
+  val default_url = "https://github.com/mozilla/pdf.js/releases/download"
+  val default_version = "2.14.305"
+
+  def build_pdfjs(
+    base_url: String = default_url,
+    version: String = default_version,
+    target_dir: Path = Path.current,
+    progress: Progress = new Progress
+  ): Unit = {
+    /* component name */
+
+    val component = "pdfjs-" + version
+    val component_dir =
+      Components.Directory(target_dir + Path.basic(component)).create(progress = progress)
+
+
+    /* download */
+
+    val download_url = base_url + "/v" + version
+    Isabelle_System.with_tmp_file("archive", ext = "zip") { archive_file =>
+      Isabelle_System.download_file(download_url + "/pdfjs-" + version + "-legacy-dist.zip",
+        archive_file, progress = progress)
+      Isabelle_System.extract(archive_file, component_dir.path)
+    }
+
+
+    /* settings */
+
+    component_dir.write_settings("""
+ISABELLE_PDFJS_HOME="$COMPONENT"
+""")
+
+
+    /* README */
+
+    File.write(component_dir.README,
+      """This is PDF.js from
+""" + download_url + """
+
+
+        Makarius
+        """ + Date.Format.date(Date.now()) + "\n")
+  }
+
+
+  /* Isabelle tool wrapper */
+
+  val isabelle_tool =
+    Isabelle_Tool("component_pdfjs", "build component for Mozilla PDF.js",
+      Scala_Project.here,
+      { args =>
+        var target_dir = Path.current
+        var base_url = default_url
+        var version = default_version
+
+        val getopts = Getopts("""
+Usage: isabelle component_pdfjs [OPTIONS]
+
+  Options are:
+    -D DIR       target directory (default ".")
+    -U URL       download URL (default: """" + default_url + """")
+    -V VERSION   version (default: """" + default_version + """")
+
+  Build component for PDF.js.
+""",
+          "D:" -> (arg => target_dir = Path.explode(arg)),
+          "U:" -> (arg => base_url = arg),
+          "V:" -> (arg => version = arg))
+
+        val more_args = getopts(args)
+        if (more_args.nonEmpty) getopts.usage()
+
+        val progress = new Console_Progress()
+
+        build_pdfjs(base_url = base_url, version = version, target_dir = target_dir,
+          progress = progress)
+      })
+}