File Chunk Analyzer
Upload any PNG, IFF (ILBM), WAV, or AVI file to analyze its internal chunk structure. Our File Chunk Analyzer identifies each chunk by its type code, displays offsets and sizes, validates CRC-32 checksums (PNG), and provides format-specific descriptions for every block of data. All processing is local in your browser - no signup required.
Upload any PNG, IFF (ILBM), WAV, or AVI file to analyze its internal chunk structure. Lists all chunks with type, offset, size, CRC validity (PNG), hex preview, and format-specific descriptions.
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Supports PNG, IFF (ILBM), WAV, and AVI files
Upload a PNG image, IFF (ILBM) bitmap, WAV audio file, or AVI video file to see its internal chunk structure. The analyzer reads the file signature to identify the format, then parses each chunk sequentially, displaying the chunk type, byte offset, data size, CRC-32 checksum (PNG only), a hex preview of the first bytes, and a format-specific description. For PNG files, the CRC column shows whether each chunk's checksum validates correctly. All processing is local in your browser - no data is uploaded to any server.
Why Use Our File Chunk Analyzer?
Instant Chunk Structure Parsing
Upload any supported file and instantly see its full internal chunk structure. Our File Chunk Analyzer reads the file signature to detect the format (PNG, IFF, WAV, or AVI), then parses every chunk sequentially, displaying type, offset, size, and hex preview - all in milliseconds with no server uploads.
Detailed Chunk-Level Analysis
Each chunk is displayed in a sortable table with its four-character type code, byte offset within the file, data size, hex preview of the first bytes, and a format-specific description. For PNG files, CRC-32 checksums are validated and shown with pass/fail indicators.
CRC-32 Validation for PNG Files
PNG chunks include a CRC-32 checksum for data integrity verification. The analyzer computes the CRC for each chunk and compares it against the stored value, clearly marking valid checksums in green and mismatches in red - a valuable feature for file integrity analysis and forensic examination.
100% Private Browser Processing
Your files never leave your device. All format detection, chunk parsing, and CRC validation happens locally in your browser using JavaScript. No data is uploaded to any server - complete privacy guaranteed for sensitive file analysis.
Common Use Cases for File Chunk Analyzer
File Integrity & Forensic Analysis
Forensic analysts can examine the chunk structure of PNG and IFF files to verify integrity, check CRC checksums for data corruption, and identify unusual or unexpected chunks that may indicate tampering or hidden data within the file structure.
File Format Reverse Engineering
Reverse engineers studying unknown or proprietary chunk-based formats can use the analyzer to understand how PNG, IFF, WAV, and AVI structures work. The detailed chunk descriptions and hex previews provide a foundation for understanding similar binary container formats.
Software Development & Debugging
Developers building file parsers, image loaders, or audio/video processing tools can verify that their output files have the correct chunk structure. Inspect individual chunks, validate sizes and offsets, and debug malformed files by examining their binary layout.
Corrupted File Diagnosis
When a PNG image or WAV audio file fails to open, the chunk analyzer can help diagnose the problem. Check for missing critical chunks (IHDR, data), incorrect sizes, or CRC mismatches that indicate where the corruption occurred.
Computer Science Education
Students learning about binary file formats and container structures can explore how real-world formats organize data into chunks. See how PNG images store metadata, palettes, and pixel data in separate, self-describing chunks with integrity checks.
Digital Preservation & Archiving
Archivists and digital preservation specialists can verify that PNG and WAV files in their collections have valid internal structures. Check chunk integrity, identify metadata-rich chunks, and ensure files conform to format specifications before long-term storage.
Understanding File Chunk Structures
What is a Chunk-Based File Format?
A chunk-based file format organizes data into discrete, self-describing blocks called chunks. Each chunk typically starts with a header containing a four-character type identifier (like IHDR, RIFF, or fmt ) and a size field indicating how many bytes of data follow. This modular design allows applications to skip unknown chunks, add metadata without breaking compatibility, and verify integrity through checksums. Chunk-based formats are used extensively in multimedia files - PNG images, WAV audio, AVI video, and IFF (Interchange File Format) files all use variations of this architecture. Understanding chunk structures is essential for file forensics, format reverse engineering, and software development involving binary data processing.
How the File Chunk Analyzer Works
- Read & Detect: You upload a file and the analyzer reads the first bytes to detect the format by its magic number signature. PNG files start with the 8-byte signature
89 50 4E 47, while RIFF-based formats (WAV, AVI) start with52 49 46 46and IFF files start with46 4F 52 4D. - Parse Chunks:Based on the detected format, the analyzer walks through the file sequentially, reading each chunk's header, extracting the type code and data size, and recording the byte offset. For PNG files, it also computes and validates the CRC-32 checksum for every chunk.
- Display Results:Each parsed chunk is displayed in a structured table showing its index, type code, byte offset, data size, CRC validity (for PNG), hex preview of the data, and a format-specific description explaining the chunk's purpose and contents.
Supported File Formats & Chunk Types
- PNG (Portable Network Graphics): Parses all standard chunk types including IHDR (image header), PLTE (palette), IDAT (image data), IEND (end marker), tEXt/zTXt/iTXt (text metadata), gAMA (gamma), cHRM (chromaticity), sRGB (color space), bKGD (background), pHYs (physical dimensions), tRNS (transparency), and eXIf (EXIF metadata). CRC-32 checksums are validated for every chunk.
- IFF (Interchange File Format / ILBM): Parses FORM-based IFF files used by Commodore Amiga ILBM images. Recognizes BMHD (bitmap header), CMAP (color map), CAMG (viewport mode), CRNG (color range), BODY (image data), ANNO, AUTH, NAME, and copyright chunks.
- WAV (Waveform Audio): Parses RIFF-based WAV files. Recognizes
fmt(format header with sample rate, channels, bit depth),data(audio samples),fact,LIST,cue,smpl, and other common WAV sub-chunks. - AVI (Audio Video Interleave): Parses RIFF-based AVI files. Recognizes
avih(AVI header with frame count and dimensions),strl/strh(stream headers),strf(stream format),00dc/00db(video frames),01wb(audio stream),idx1(index), andJUNK(padding).
Privacy, Security & Availability
The File Chunk Analyzer processes all files entirely within your browser using client-side JavaScript. No file data is ever uploaded to any server - every byte of your file stays on your device. There are no file size limits, no signup requirements, and no usage caps. The tool is 100% free to use with no hidden premium features. Whether you are analyzing a small PNG icon or a large AVI video file, your privacy and security are guaranteed.
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Frequently Asked Questions About File Chunk Analyzer
A file chunk analyzer is a tool that reads and interprets the internal structure of chunk-based file formats like PNG, IFF, WAV, and AVI. It identifies each chunk by its type code, displays its size and byte offset, shows a hex preview of its data, and provides format-specific descriptions. For PNG files, it also validates CRC-32 checksums to verify data integrity.
The analyzer supports PNG (Portable Network Graphics), IFF/ILBM (Interchange File Format used by Commodore Amiga), WAV (Waveform Audio), and AVI (Audio Video Interleave). All of these formats use a chunk-based architecture where data is organized into self-describing blocks with type identifiers and size fields.
A chunk is a discrete block of data within a file that has a type identifier (usually 4 characters), a size field, and the data itself. Chunks are the building blocks of formats like PNG, where each chunk stores a specific type of information - such as image dimensions (IHDR), pixel data (IDAT), or metadata (tEXt). Chunks can appear in any order (except critical ones), making the format extensible.
CRC (Cyclic Redundancy Check) is an error-detecting code stored with each PNG chunk. The analyzer computes the CRC-32 checksum of the chunk type and data, then compares it against the stored value. A green checkmark indicates the CRC is valid (data is intact), while a red indicator suggests the chunk data may be corrupted or altered.
There are no artificial limits. Since the analyzer processes files locally in your browser, the practical limit depends on your device memory. Most computers can easily handle files up to several hundred megabytes. Large AVI video files may take slightly longer to parse due to the high chunk count.
Currently, the File Chunk Analyzer displays results on-screen in a structured table. You can use your browser's print function or copy the data manually. The tool focuses on providing clear, real-time analysis with format-specific descriptions and CRC validation for forensic and educational purposes.
Absolutely. The File Chunk Analyzer processes everything locally in your browser using JavaScript. Your files are never uploaded to any server - all format detection, chunk parsing, and CRC validation happens on your device. This ensures complete privacy for sensitive files.
Yes! 100% free with no signup, no account, no usage limits, and no hidden premium features. Analyze as many files as you need - completely free, forever. All processing is done in your browser with no server-side dependencies.