Single-page web app to convert between PHP archives (.phar) and ZIP files entirely client‑side. No server, no build step, works from file:// or any static host.

• PHAR → ZIP: Manual PHAR parser (stub + manifest + file data), supports deflate (GZ). Warns on BZip2.
• ZIP → PHAR: Builds PHAR with stub, manifest, raw data (no compression), CRC32, and SHA1 placeholder signature (GBMB magic).
• Auto detect: One drop zone; dropping .phar converts to .zip, dropping .zip converts to .phar.
• Verification: After ZIP → PHAR, the app re-parses the generated PHAR and compares CRC32 of every file.
• Offline after first load: Uses CDN JS (JSZip, FileSaver, pako); once cached by the browser, works offline.

1. Open index.html (double-click is fine; first time needs network for CDNs).
2. Drag & drop a .phar or .zip onto the drop zone, or click to choose.
3. The app detects the type:
   • .phar → downloads <name>.zip
   • .zip → downloads <name>.phar
4. For ZIP → PHAR, a verification line shows how many files matched CRC after repack.

• Parsing PHAR: Finds __HALT_COMPILER(); ?> stub end, reads manifest (length‑prefixed), then file entries; handles deflate based on flags & 0xF000.
• Building PHAR: Stub text:

  <?php
  // PocketMine-MP Plugin
  __HALT_COMPILER(); ?>

  followed by CRLF. Manifest uses API 0x0011, no alias/metadata, no compression. Signature block: type 0x00000001, 20 zero bytes, magic GBMB.
• Compression: None when creating PHAR; only deflate is decompressed when reading PHAR. BZip2 is not supported in-browser.
• CRC32: Implemented manually (poly 0xEDB88320).

• Vanilla HTML/CSS/JS (no frameworks)
• JSZip 3.10.1 (CDN)
• FileSaver 2.0.5 (CDN)
• pako 2.1.0 (CDN)

• index.html - layout + drop zone
• style.css - styling (Apple-like light theme)
• script.js - parsing/building logic

• BZip2-compressed PHAR entries are not supported.
• Very large files depend on browser memory limits.

• Inspired by the parsing approach from easy-phar/easy-phar.github.io and pharjs/phar.js.