ANALYSIS FORENSIC DIAGNOSTIC

Truncated File Detector

Find out whether a file ended before its structure was actually complete.

File

Original file is never modified · 100% local — nothing is uploaded

How Truncated File Detector works

  1. Identify the format from its magic bytes.
  2. Where the format declares its own length — a RIFF chunk size (WAV/AVI/BMP/WebP), a ZIP central directory entry count, a SQLite page count — compare it against the actual bytes on disk. This is the strongest evidence available, and where it exists, the result includes a real completion percentage.
  3. Where the format doesn't declare a length, walk its actual structure (PNG chunks, JPEG marker segments, PDF's xref/trailer) as far as it goes, and report exactly where it stopped.
  4. Check for a required trailing marker (JPEG EOI, PNG IEND, ZIP end-of-central-directory, PDF %%EOF) at the correct structural position — not just anywhere in the file.
  5. Check for evidence this isn't truncation at all — a filename matching a split-archive pattern, or valid structure followed by extra trailing bytes.

Supported formats

Real structural evidence for JPEG, PNG, GIF, BMP, WebP, WAV, AVI, ZIP (and DOCX/XLSX/PPTX/JAR/APK), PDF, SQLite, JSON, and XML. Anything else still gets format identification and a footer check where one exists — Cracked Bunker says so honestly when there isn't a reliable completion rule for a format yet.

Common error messages this diagnoses

If you're here because something threw one of these, this tool shows you exactly what's wrong and how much is recoverable:

  • "Unexpected end of file" — the exact symptom this tool is built to confirm or rule out with real evidence.
  • "The download did not complete" — a truncated download is the most common real-world cause.
  • "Premature end of file" — same signal, different app's wording.

What this tool doesn't do (yet)

No fabricated completion percentage is ever shown — a percentage only appears where a format actually declares its own length (RIFF's chunk size, SQLite's page count, ZIP's entry count) and the math is exact. For JPEG, GIF, PDF, and unrecognized formats, the result is deliberately qualitative: real evidence, no invented number. There's no MP4/MOV box parsing, no PE/ELF/Mach-O section-table analysis, and no generic compression-stream decode-until-fail check yet — those need real parsers this tool doesn't have. There's no batch mode, no folder scanning, and no comparison against a known-good reference copy. This tool only diagnoses — it never modifies the uploaded file or attempts a repair itself; that's always a specialist tool's job, linked from the result above.