Read the physical layout of a WebP container without decoding or modifying its pixels. The inspector walks the declared RIFF bounds, records each top-level FourCC, byte offset, payload length, padding byte, and total stored footprint, and preserves the findings as JSON for debugging.
How to use RIFF Chunk Inspector
- Choose one or more genuine WebP files whose container layout you need to audit.
- Run the inspector to parse ordered RIFF chunks within the file's declared bounds.
- Review the compact chunk count and download the JSON when exact offsets or byte sizes need to be shared.
What this tool is good at
When to use RIFF Chunk Inspector
Debug RIFF layout with evidence
Audit chunk order, offsets, payload sizes, padding, and declared container coverage when an encoder or delivery pipeline produces an unexpected file. Work from the selected WebP's actual bytes, dimensions, or decoded pixels instead of assuming that an extension, filename, or one successful preview proves the underlying implementation.
Prepare a repeatable developer handoff
The JSON preserves zero-based offsets and separates payload bytes from headers and alignment padding for precise comparisons. Keep the generated asset, report, markup, or command beside a ticket or publishing change so another developer can reproduce the decision and verify the exact inputs.
Keep unreleased assets private
Inspect campaign media, client images, product artwork, and internal fixtures in the current browser tab without creating an image-processing upload or remote conversion job.
How to choose the right settings
Match settings to the consuming system
Audit chunk order, offsets, payload sizes, padding, and declared container coverage when an encoder or delivery pipeline produces an unexpected file. Confirm filename conventions, layout widths, codec availability, metadata policy, and quality requirements in the real CMS, build pipeline, browser, or command-line environment.
Verify generated output, not only controls
The JSON preserves zero-based offsets and separates payload bytes from headers and alignment padding for precise comparisons. Open downloaded images, read the complete report, or review generated code before publishing; a convenient default cannot know every repository path, responsive layout, or compatibility rule.
Keep the source as the authority
The report does not expand VP8 or VP8L codec syntax, repair corruption, or prove that unknown application chunks are safe or necessary. Store the untouched WebP until every derivative or integration change has been tested and accepted.
Practical workflow and output details
A bounds-aware RIFF parser walks only complete top-level chunks and never decompresses or rewrites image payloads. Processing uses browser APIs, bounded typed-array parsing, Canvas, or local Blob generation. No selected image bytes are submitted to PicConverters for processing.
The report does not expand VP8 or VP8L codec syntax, repair corruption, or prove that unknown application chunks are safe or necessary. The page states this boundary explicitly so a local convenience tool is not mistaken for a full codec debugger, perceptual quality lab, shell runtime, deployment system, or irreversible source-of-truth editor.
Format behavior and limitations
Only top-level RIFF chunks are enumerated; compressed VP8 and VP8L bitstreams are identified but not expanded into codec syntax.
Offsets are zero-based byte positions in the selected file, and malformed bounds are rejected rather than guessed.
Frequently asked questions
Does this change the WebP?
No. It reads bytes and creates a separate JSON report.
What is a FourCC?
It is the four-character identifier used for RIFF chunks such as VP8X, VP8L, ANIM, EXIF, or ICCP.
Why can stored bytes exceed payload bytes?
Each chunk has an eight-byte header and odd payloads receive one padding byte.
Related WebP tools
WebP File Analyzer
Create a detailed local report covering WebP encoding, dimensions, chunks, payload bytes, overhead, animation, alpha, and metadata.
WebP Validator
Validate RIFF bounds, image payloads, animation structure, dimensions, and feature-flag consistency without altering the file.
webpmux GUI
Inspect WebP mux structure or create byte-preserving copies with EXIF-only or all standard metadata chunks removed.