PNG Format Viewer

Drop a PNG file here, or select a PNG file

PNG (Portable Network Graphics) is a widely used format for still images on the web and in documents, with good lossless compression.

A PNG file starts with an 8-byte signature, followed by chunks containing control data, metadata, and image data. Each chunk has a 4-byte length, 4-byte type code, 4-byte CRC, and type-specific fields.

This tool reads a PNG file and inspects its structure, listing chunks and fields plus any format violations. Useful for hidden metadata and for building compatible PNG readers/writers.

Chunks:
OffsetRaw DataSummaryDataErrors

Related Tools

How to Use

🔍 Overview

Analyze PNG file structure in depth — signature, chunks, metadata, and validation details for developers and designers.

📋 Capabilities

  • Structure: Parse the 8-byte signature and all chunks.
  • Chunk details: Offset, type, length, and CRC for each chunk.
  • Metadata: Extract embedded metadata.
  • Validation: Check conformance to the PNG specification.
  • Diagnostics: Report format errors.

💡 Steps

  1. Click the upload area or drag a PNG file in.
  2. The file structure is parsed automatically.
  3. Review chunk details in the table.
  4. Check the "Errors" column for issues.
  5. Inspect what each chunk contains.

🎯 Use Cases

  • Learning the PNG format.
  • Image software development and debugging.
  • PNG integrity checks.
  • Finding hidden metadata.
  • Spec validation.
  • Digital forensics and security review.
  • Compression research.

📊 Chunk Types

  • IHDR: Image header — width, height, color type, etc.
  • PLTE: Palette (indexed-color images only).
  • IDAT: Compressed image data.
  • IEND: End of image marker.
  • tEXt/iTXt/zTXt: Text and metadata.
  • gAMA: Gamma information.
  • cHRM: Chromaticity.
  • Other: Various auxiliary chunks.

✨ Highlights

  • Full parse: All standard PNG chunks.
  • Rich detail: Offsets, raw data, and summaries.
  • Error detection: Format and spec violations.
  • Clear tables: Structure shown in tabular form.
  • Instant analysis: Results right after upload.
  • Local only: Analysis runs entirely in the browser.

⚠️ Notes

  • PNG files only — not other image formats.
  • Large files may take longer to parse.
  • Non-standard or damaged PNGs may not parse fully.
  • Results are for technical analysis, not guaranteed 100% accuracy.
  • Files are not uploaded to a server.
  • Use a modern browser for the best experience.

💡 Tips

  • Start with IHDR for basic image properties.
  • Check IDAT count and size for compression insight.
  • Look at text chunks (tEXt, iTXt, etc.) for hidden metadata.
  • Use CRC values to verify chunk integrity.
  • Compare different PNGs to learn format patterns.
  • Use error messages to diagnose format problems.

❓ FAQ

  • Why can’t some PNG files be parsed?
    The file may be corrupt, non-standard, or not a real PNG. Ensure it is complete and valid.
  • What does the "Errors" column show?
    Format errors, CRC failures, wrong chunk order, and other spec violations.
  • What is an offset?
    The byte position of a chunk in the file — useful for low-level inspection.
  • What is CRC?
    Cyclic redundancy check — detects corruption during transfer or storage.
  • Can this tool repair errors?
    No — it only analyzes and reports. Use dedicated image editors to repair files.
Site Navigation