Archive Integrity Checker
Verify ZIP and GZIP archives for corruption online for free. Our archive integrity checker computes CRC32 checksums for every file entry in a ZIP archive and for the full GZIP stream, then compares them against the stored checksums in the archive header. Shows stored CRC32 vs computed CRC32 per entry with OK / CORRUPTED / UNSUPPORTED status badges. Detects bit rot, partial downloads, and storage corruption instantly. All processing runs locally in your browser — no signup required, no file size limits.
Drop your archive here
or click to browse
ZIP (.zip) and GZIP (.gz) archives supported
CRC32 checksums are computed using the standard IEEE 802.3 polynomial (0xEDB88320). ZIP entries using DEFLATE compression are decompressed using the browser's native DecompressionStream API before CRC32 verification. Entries using BZIP2, LZMA, or other methods are marked as unsupported.
Why Use Our Archive Integrity Checker?
Instant CRC32 Verification for ZIP and GZIP
Our archive integrity checker verifies CRC32 checksums for every file entry in a ZIP archive and for the full GZIP stream — instantly in your browser. Detects bit-level corruption, truncated files, and mismatched checksums with a clear OK / CORRUPTED status per entry.
Secure Archive Integrity Checker Online
Your archive never leaves your device when you use our archive integrity checker online. All CRC32 computation and decompression runs entirely in your browser using the native DecompressionStream API — no server uploads, no data retention, 100% private.
Per-Entry Breakdown with Stored vs Computed CRC32
See the stored CRC32 and computed CRC32 side-by-side for every ZIP entry — including filename, compressed size, uncompressed size, and compression method. Instantly identify which specific files are corrupted in a multi-file archive.
Archive Integrity Checker — No Installation
Verify ZIP and GZIP archive integrity directly in your browser. No unzip tools, no command-line utilities, no Python scripts required. Our free archive integrity checker works on any device with a modern browser — no signup, no file size limits.
Common Use Cases for Archive Integrity Checker
Download Verification
Verify that a ZIP or GZIP file downloaded from the internet was not corrupted during transfer. Our archive integrity checker detects partial downloads, network errors, and storage corruption before you extract the archive.
Backup Archive Validation
Validate ZIP and GZIP backup archives before relying on them for disaster recovery. Confirm that every file in the backup has a matching CRC32 checksum — catching silent corruption that occurred during backup creation or storage.
Software Package Integrity
Verify the integrity of ZIP-packaged software distributions, npm packages, Python wheels, and JAR files before installation. Detect tampering or corruption in downloaded packages before they reach your build pipeline.
Log Archive Verification
Verify GZIP-compressed log archives (.log.gz) before importing them into log analysis tools. Corrupted log archives can cause silent data loss in analytics pipelines — our archive integrity checker catches corruption before it propagates.
Long-Term Storage Validation
Periodically verify ZIP archives stored on external drives, NAS devices, or cold storage to detect bit rot and media degradation. CRC32 mismatches indicate that stored data has changed since the archive was created.
CI/CD Artifact Verification
Integrate archive integrity checking into your CI/CD pipeline to verify build artifacts before deployment. Confirm that ZIP and GZIP artifacts produced by your build system have valid checksums before they are published or deployed.
Understanding Archive Integrity Checking
What is Archive Integrity Checking?
How CRC32 Verification Works
ZIP vs GZIP Archive Structure
What Causes Archive Corruption?
Related Tools
JSON Key Shortener
Shorten verbose JSON keys to single letters or abbreviated forms — shows size reduction and provides a downloadable key mapping file for restoration. Free online JSON key shortener.
JSON vs MessagePack Size Comparison
Compare JSON byte size vs MessagePack encoding for any payload — shows exact savings, type-by-type breakdown, and MessagePack hex preview. Free online JSON vs MessagePack comparison.
String Decompressor (GZIP/LZ)
Decompress GZIP+Base64, DEFLATE+Base64, and LZ-String compressed payloads back to readable text — supports all three LZ-String variants. Free online string decompressor.
ZIP File Extractor
Extract files from any ZIP archive client-side — browse contents, preview text files, download individual files or all at once. Free online ZIP extractor, no signup required.
Frequently Asked Questions About Archive Integrity Checker
An archive integrity checker verifies that a ZIP or GZIP archive has not been corrupted by computing CRC32 checksums for each file entry and comparing them against the stored checksums in the archive header. Our free archive integrity checker online runs entirely in your browser — no server upload required.
CRC32 (Cyclic Redundancy Check 32-bit) is a checksum algorithm that produces a 4-byte fingerprint of any data. ZIP and GZIP archives store the CRC32 of each file's uncompressed data in the archive header. When you extract or verify the archive, the CRC32 is recomputed and compared — any mismatch indicates that the data was corrupted during storage or transfer.
Yes. All CRC32 computation and decompression runs entirely in your browser using the native DecompressionStream API. Your archive is never uploaded to any server, never stored remotely, and never transmitted over the network. Your data stays completely private.
Yes — 100% free, forever. No signup, no account, no premium tier, no file size limits, and no ads interrupting your workflow.
The archive integrity checker fully verifies ZIP entries using Stored (method 0, no compression) and DEFLATE (method 8) compression — the two most common methods. Entries using BZIP2 (method 12), LZMA (method 14), or other methods are listed but marked as "unsupported" for CRC verification, since the browser's native DecompressionStream API only supports DEFLATE.
A "CORRUPTED" status means the CRC32 checksum computed from the file's data does not match the CRC32 stored in the archive header. This indicates the file data was modified or damaged after the archive was created — either during download, storage, or transmission. The file cannot be trusted and should not be used.
An "UNSUPPORTED" status means the ZIP entry uses a compression method that the browser's native DecompressionStream API cannot decompress (e.g. BZIP2, LZMA, ZSTD). The entry is listed with its stored metadata, but CRC32 verification cannot be performed. The entry may or may not be corrupted — use a native tool like unzip or 7-Zip to verify these entries.
No — password-protected ZIP archives use encryption that prevents reading the file data without the password. The archive integrity checker cannot decrypt or verify encrypted ZIP entries. Use a native tool like 7-Zip with the correct password to verify encrypted archives.
Since all processing runs in your browser, the practical limit depends on your device's available RAM. Most modern devices handle archives up to several hundred megabytes without issues. Very large archives (1 GB+) may cause the browser tab to run out of memory — for those, use the command-line unzip -t or gzip -t commands.