{
  "id": "magic/zip",
  "family": "magic",
  "slug": "zip",
  "title": "ZIP signature (PK\\x03\\x04)",
  "summary": "A ZIP archive begins with a local file header whose signature is 'PK' (0x50 0x4B, the initials of Phil Katz) followed by 0x03 0x04. Empty archives and some variants start with the central-directory (PK\\x01\\x02) or end-of-central-directory (PK\\x05\\x06) signatures.",
  "kind": "signature",
  "aliases": [
    "ZIP magic",
    "PKZIP",
    "PK\\x03\\x04"
  ],
  "status": "de-facto",
  "verification": "verified",
  "tier": "C",
  "source_url": "https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT",
  "source_version": "PKWARE APPNOTE.TXT, .ZIP File Format Specification, 4.3.7 (local file header signature 0x04034b50)",
  "retrieved_date": "2026-05-29",
  "attribution": [
    {
      "claim_ref": "ext.magic_hex",
      "source_url": "https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT",
      "source_version": "APPNOTE.TXT 6.3.x, section 4.3.7",
      "note": "Local file header signature is 0x04034b50, stored little-endian => bytes 50 4B 03 04 ('PK\\x03\\x04')."
    },
    {
      "claim_ref": "ext.notes",
      "source_url": "https://en.wikipedia.org/wiki/List_of_file_signatures",
      "source_version": "retrieved 2026-05-29",
      "note": "Corroborates PK\\x03\\x04 / PK\\x05\\x06 / PK\\x07\\x08 ZIP signatures and the shared-base-format note (jar, docx, xlsx, odt, epub, apk all ZIP containers)."
    }
  ],
  "see_also": [
    "magic/gzip",
    "magic/java-class",
    "magic/7z"
  ],
  "ext_type": "file-signature@1",
  "ext": {
    "magic_hex": "50 4B 03 04",
    "offset": 0,
    "magic_ascii": "PK\\x03\\x04",
    "extensions": [
      "zip",
      "jar",
      "docx",
      "xlsx",
      "pptx",
      "odt",
      "epub",
      "apk"
    ],
    "mime": "application/zip",
    "spec": "PKWARE APPNOTE.TXT .ZIP File Format Specification",
    "notes": [
      "Signatures are 32-bit values stored little-endian: local file header 0x04034b50 => 50 4B 03 04.",
      "Empty archive: 'PK\\x05\\x06' (50 4B 05 06, end of central directory).",
      "Spanned/split markers use 'PK\\x07\\x08' (50 4B 07 08).",
      "Many formats are ZIP containers and share this magic: JAR, DOCX/XLSX/PPTX (OOXML), ODT (ODF), EPUB, APK. Disambiguation requires inspecting the archive contents (e.g. mimetype entry, META-INF).",
      "The 'PK' bytes are the initials of Phil Katz, author of PKZIP."
    ]
  },
  "updated": "2026-05-29T00:00:00Z"
}