Archive Analyzer
Upload any archive file (ZIP, RAR, 7z, TAR, GZ, BZ2, XZ) to get a detailed structural analysis. The Archive Analyzer shows compression methods, encryption type, file count, total compressed and uncompressed sizes, compression ratio, file type distribution, and per-file details for ZIP archives. All processing runs locally in your browser - no data uploaded, no signup required.
Upload any archive file (ZIP, RAR, 7z, TAR, GZ, BZ2, XZ) to get a detailed structural analysis. Shows compression methods, encryption type, file count, total compressed/uncompressed sizes, compression ratio, file type distribution, largest files, and per-file details for ZIP archives. All processing happens entirely in your browser.
Drop an archive file here or click to browse
Supports ZIP, RAR, 7z, TAR, GZ, BZ2, XZ - max 200 MB
The Archive Analyzer first identifies the archive format by reading the file header (magic bytes). For ZIP archives, it uses the JSZip library to fully parse the archive structure: every file entry is inspected for its compression method, compressed and uncompressed sizes, CRC-32 checksum, encryption flags, and modification date. The analysis computes overall compression ratios, file type distributions, and size category breakdowns. For other formats (RAR, 7z, TAR, GZ, BZ2, XZ), the format is detected by its signature but detailed per-entry analysis is limited. All processing runs locally in your browser - no data is ever uploaded.
Why Use Our Archive Analyzer?
Multi-Format Archive Support
Analyzes ZIP, RAR (v4/v5), 7z, TAR, GZIP, BZIP2, and XZ archives. For ZIP files, the tool provides deep per-entry analysis including compression methods, CRC-32 checksums, encryption flags, and modification dates. Other formats are identified by their magic bytes with format-level structural information.
Detailed Compression Analytics
View overall compression ratio, total space saved, and per-file compression performance. The tool breaks down compression by method (Stored, Deflate, BZIP2, LZMA, PPMd, and more), shows file size distribution across five categories (<1 KB to >10 MB), and highlights the largest files in the archive with their individual savings.
Full Archive Contents Browser
Browse all files and directories in the archive with search and filtering. Each entry shows its compression method, compressed/uncompressed size, CRC-32 checksum, ratio, and encryption status. Expand any entry for full details including modification date. Filter by name to quickly find specific files.
Encryption & Security Analysis
Detects encryption on archive entries including legacy PKWARE encryption and AES-256 (WinZip). The tool identifies the encryption type, strength level (weak/strong), and provides warnings about weak encryption. Also detects archives with mixed compression methods, very low compression ratios, and other structural anomalies.
Common Use Cases for Archive Analyzer
Security Audit of Archive Files
Security analysts can inspect archive files for encryption methods, detect weak legacy encryption (PKWARE), and verify that sensitive archives use AES-256 encryption. The tool also helps identify suspicious files within archives, detect mixed compression methods that may indicate tampering, and verify CRC-32 checksums for file integrity.
Storage Optimization Analysis
System administrators can analyze archive compression efficiency to optimize storage. The tool shows compression ratios, space saved, and file type distribution - helping identify archives that could benefit from re-compression with better algorithms, or detecting archives where compression is ineffective due to already-compressed content.
Download & Transfer Verification
Before downloading large archives or transferring files between systems, analyze the archive structure to verify integrity. Check total uncompressed size against available disk space, verify that all expected files are present, and confirm that the archive uses standard compression methods compatible with your extraction tools.
Malware & Suspicious Content Analysis
Scan archives for suspicious file types, hidden files, unusual compression methods, or encrypted entries that may evade detection. The detailed file listing helps identify files with double extensions, executable content disguised in archives, and other common malware delivery techniques used in phishing campaigns.
Archive Forensics & Data Recovery
Digital forensics investigators can examine archive structure to understand how data was packaged, when files were last modified, and what compression methods were used. The per-file CRC-32 checksums help verify data integrity and can be cross-referenced with known file signatures for forensic analysis.
Learning & Education
Students and educators can use the archive analyzer to understand how different compression algorithms work. See the actual compression ratios achieved by Deflate vs BZIP2 vs LZMA, explore how file types affect compressibility, and learn about archive structure, encryption methods, and checksums.
Understanding Archive File Analysis
What Is Archive File Analysis?
Archive file analysis is the process of examining the internal structure of compressed archive files to extract metadata about their contents, compression methods, encryption, and structural integrity. Archives use various compression algorithms (Deflate, LZMA, BZIP2, PPMd, etc.) to reduce file sizes, and may include encryption(AES-256, traditional PKWARE) for security. Each file within the archive is stored with metadata including its original and compressed sizes, CRC-32 checksum for integrity verification, compression method identifier, and modification timestamp. Understanding these properties is essential for security auditing, storage optimization, data forensics, and software development workflows that involve archive manipulation.
Archive Format Signatures & Capabilities
- ZIP (.zip): The most widely supported archive format. Uses Deflate compression by default, supports AES-256 encryption (WinZip) and legacy PKWARE encryption, up to 4 GB per entry (ZIP32) or virtually unlimited (ZIP64). Our tool provides full per-entry analysis for ZIP files including compression methods, CRC-32 checksums, encryption detection, and version needed. Signature:
PK 0x0304. - RAR (.rar): Proprietary format by Eugene Roshal. Uses RAR-specific compression algorithm (LZSS + PPMd variants). RAR v4 uses the signature
Rar! 0x1A 0x07, while RAR v5 usesRar! 0x1A 0x07 0x01 0x00. Supports AES-128 and AES-256 encryption, solid archives, and multi-volume archives. Detection by signature only - detailed entry analysis is not available. - 7z (.7z): Open-source format by Igor Pavlov (7-Zip). Uses LZMA or LZMA2 compression with optional solid archiving. Supports AES-256 encryption and file name encryption. Known for high compression ratios but slower compression speed. Signature:
7z 0xBC 0xAF 0x27 0x1C. Detection by signature only. - TAR (.tar): Tape Archive format - no compression by default (just concatenation). Often combined with GZIP (.tar.gz/.tgz), BZIP2 (.tar.bz2), or XZ (.tar.xz) for compression. Stores POSIX file permissions, ownership, and metadata. Signature:
ustarat offset 257. - GZIP (.gz): Single-file compression using Deflate algorithm. Commonly used with tar archives (.tar.gz). Includes file name and modification timestamp in the header. Signature:
0x1F 0x8B. Detection by signature only.
How Our Archive Analyzer Works
- Format Detection: The tool reads the first bytes of the uploaded file and matches them against known archive signatures (magic bytes). Each signature is checked at its specific offset - ZIP at offset 0, TAR at offset 257, and others at their respective positions. The detected format determines the depth of analysis possible.
- ZIP Parsing (Deep Analysis): For ZIP archives, JSZip fully parses the central directory structure. For each file entry, we extract the compressed and uncompressed sizes, compression method (mapped to a human-readable name from the PKWARE APPNOTE), CRC-32 checksum, encryption flags (bit 0 and bit 6 in the general-purpose bit flag), modification date, and whether the entry is a directory. The version needed to extract is determined from the highest version required by any entry.
- Aggregation & Reporting: Individual entry data is aggregated into overall statistics: total compressed/uncompressed size, compression ratio, space saved, file type distribution (by extension), compression method usage frequency, and file size category distribution. The top 5 largest files are identified, and warnings are generated for encryption weakness, low compression efficiency, or structural anomalies.
Limitations & Supported Formats
Full analysis (per-entry): ZIP archives only. The JSZip library provides complete access to ZIP file structure including compression methods, CRC-32 checksums, encryption flags, and file metadata. Signature-based detection only: RAR, 7z, TAR, GZIP, BZIP2, and XZ formats are detected by their magic bytes but detailed per-entry analysis is not available in the browser environment. The tool clearly indicates this limitation in its results. File size limit: Archives up to 200 MB are supported. Larger files may cause browser memory issues. Password-protected archives: Encrypted ZIP entries cannot have their contents extracted, but metadata (compressed size, encryption type, compression method) is still readable from the central directory. All processing is local: Files never leave your device - no uploads, no signup, no data collection.
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Frequently Asked Questions About Archive Analyzer
The tool detects ZIP, RAR (v4/v5), 7z, TAR, GZIP, BZIP2, and XZ archives by reading their magic bytes (file signatures). For ZIP archives, it provides deep per-file analysis including compression methods, CRC-32 checksums, encryption flags, modification dates, and individual file sizes. For other formats (RAR, 7z, TAR, GZ, BZ2, XZ), the format is identified but detailed per-entry analysis is limited since browser-based parsing of these formats is not available.
The compression ratio is the compressed size divided by the uncompressed size. A ratio of 0.50 means the file compressed to 50% of its original size (50% space saved). The ratio is 1.00 for uncompressed (stored) files, 0.00 for perfectly compressed files, and above 1.00 if the compressed version is larger than the original (which can happen with already-compressed data like images or video). The tool also shows the space saved as both a percentage and a formatted byte value.
Yes. The tool checks each ZIP entry's general-purpose bit flag to detect encryption. It distinguishes between legacy PKWARE encryption (weak, CRC-based, indicated by bit 0) and strong encryption (bit 6, which includes AES-256). It also detects WinZip AES encryption (compression method 99). The encryption method and strength level are reported per-entry and summarized for the entire archive.
The "version needed" field indicates the minimum ZIP specification version required to extract the archive. Version 1.0 is the default (no special features). Version 2.0 is needed for Deflate compression. Version 2.1 is needed for Deflate64. Version 5.0+ is needed for AES encryption. Version 6.3+ is needed for LZMA compression. The tool shows the highest version required by any entry in the archive.
Absolutely. All archive analysis happens entirely within your browser using the JSZip library for ZIP parsing and binary header analysis for other formats. Your files are never uploaded to any server - they never leave your device. No signup, no account, no data collection, no usage tracking. Archive contents are read locally and analyzed in memory.
The tool accepts .zip, .rar, .7z, .tar, .gz, .bz2, .xz, .tgz, and .tbz2 files up to 200 MB. For best results with ZIP files, use standard ZIP archives created with common tools (WinZip, 7-Zip, macOS Archive Utility, Linux zip). Self-extracting archives (.exe) are not supported as they are executable files, not standard archives.
CRC-32 (Cyclic Redundancy Check) is a 32-bit checksum computed from the uncompressed data of each file entry. It is used to verify data integrity - if the CRC-32 of the extracted data matches the stored CRC-32, the data has not been corrupted. The tool displays CRC-32 values as 8-character hexadecimal strings for every file in the archive.
A low compression ratio (close to 1.00 or above) indicates that the archive is not compressing effectively. This is common when the archive contains already-compressed files like JPEG images, MP3 audio, MP4 video, or previously compressed archives. Some file formats (PDF with embedded images, DOCX which is itself a ZIP) also resist further compression. The tool will warn you if the compression ratio is unusually low.
Yes - 100% free, forever. No signup, no account, no premium tier, no usage limits, and no ads. Analyze as many archives as you need. All processing is done locally in your browser with zero server uploads.