Local file tool
PNG chunk inspector
Inspect chunk positions, lengths and CRC diagnostics.
18 October 2026 · Check AI Free
Inspect PNG chunks and CRCs
Read the file structure in your browser without uploading it or decoding pixels. Bounds and observed bytes are reported directly. A readable structure or matching CRC does not establish authenticity, valid credentials or file safety.
Up to 20 MiB and 4,096 structure units. Invalid lengths stop the walk at a safe boundary. Image content and private metadata field values are not displayed in the inventory.
Examples are original generated images with invented metadata. The bad-CRC example is deliberately corrupted for diagnosis.
Supported files and output
PNG up to 20 MiB and 4096 chunks. Lists exact chunk offsets, data/full lengths, order, CRC diagnostics, animation signals and unknown chunks without decoding image pixels. Invalid lengths stop the bounded walk; CRC issues retain safely bounded rows. Text values are read separately in the PNG text reader.
Read the result with its coverage
Stored fields can be edited, copied or removed. A successful read describes the selected file’s supported containers; missing fields cannot be recovered from its pixels. A damaged or unsupported container has its own result. Review private values before copying or sharing a report.
These file operations run locally. The separate image checker can send file-header data and a reduced image copy for a model reading. Read the method and limitations when that is the task you need.
Continue the task
- PNG metadata tasks: read text, locate chunks and edit selected fields — Choose a local PNG workflow for stored text, chunk ranges and CRCs, or verified text editing. Follow three defined original, empty and Unicode-edited scenes.
- Inspect PNG text chunks, duplicate keywords and decoded values — Locate tEXt, zTXt and iTXt in a real PNG inventory, read duplicate Author values and Unicode text, and distinguish compression limits from missing parameters.
- Find PNG metadata stored after IDAT image data — Compare the same compressed Comment before and after IDAT, save real chunk offsets, and verify why a scan that stops at the first image-data chunk misses stored text.
- Edit one PNG text field without re-encoding its image data — Select an exact duplicate-keyword chunk, stage a Unicode replacement, create a verified PNG copy, and re-read its changed text, valid CRCs and preserved IDAT bytes.
- Find out what a missing PNG parameters result does and does not mean — Compare a known parameters PNG with a defined locally saved text-removed copy, separate missing fields from unsupported reads, and choose a practical next file to obtain.
- EXIF viewer and exports — Inspect the stored camera, location and caption fields.
- Remove selected metadata — Create a verified static-image copy with supported categories removed.
- Choose another file operation — Browse available tools by task.