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PNG Chunk Viewer
Walk every chunk in a PNG file and verify each CRC-32 checksum.
Inspect PNG chunks
File: choose a PNG to begin
Checksums: —
How to use the PNG Chunk Viewer
- Choose a PNG file from your device.
- The tool walks the chunk list in order, checking each CRC-32 checksum.
- Read the IHDR, palette, text and image data details in the table.
Features
- Walks IHDR, PLTE, tEXt, zTXt, iTXt, IDAT and IEND
- Recomputes every CRC-32 checksum from the raw bytes
- Decodes image header, palette, gamma and text fields
- Flags truncated or corrupt chunks instead of failing
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Frequently Asked Questions
Common questions about the free online png chunk viewer.
Choose a PNG and the tool lists every chunk in order with its length, checksum result and
decoded details.
A PNG file is a sequence of chunks, and each one holds a length, a four letter type, its data
and a CRC-32 checksum.
IHDR, PLTE, IDAT and IEND are critical, while chunks such as tEXt, pHYs and gAMA are
optional.
The stored checksum does not match the data, which usually points to a corrupted or hand
edited file.
Yes. tEXt, zTXt and iTXt chunks are listed with their keyword and content so you can see the
embedded metadata.
No. The bytes are read with the FileReader API and everything is analysed inside your
browser.
The tool checks the eight byte PNG signature first, so a JPEG or GIF with a png extension
will be refused.
Yes. The viewer is fully responsive and works in the browser on phones, tablets and desktops.
No fixed limit, although very large PNG files take a little longer because every byte is
checked for its checksum.
Last updated: October 10, 2026