About LZ4 Files
LZ4 Compressed
LZ4 is an extremely fast lossless compression algorithm focused on speed over compression ratio. It can compress at over 500 MB/s per core and decompress at multiple GB/s, making it the standard choice for real-time and in-memory compression.
Family
Archives & Compressed
Extension
.lz4
MIME Type
application/x-lz4
Can Use As
4C 5A 34 46 00 01 00 00 4B 41 49 4A
ASCII: LZ4F....KAIJ
📈 Target Minimum File Size (Guaranteed ≥ KB)
Lossless JPEG Q100 + standard COM segment padding for government & exam portals
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HOW LZ4 CAME TO BE.
LZ4 was released in 2011 by Yann Collet — the same French engineer who would later design Zstandard at Facebook. Where most compression algorithms chase ratio, LZ4’s explicit goal was raw speed: decode at around 4 GB/s per single CPU core, with compression fast enough to keep pace with modern SSDs and RAM. The trade-off is ratio: LZ4 typically only shrinks data by 30-50%, less than gzip’s 60-70%. But for use cases where decompression speed matters more than storage size, LZ4 wins uncontested.
The Linux kernel accepted LZ4 for zram (compressed swap), initramfs (compressed boot images), and btrfs transparent compression. Databases (Apache Cassandra, RocksDB) use LZ4 for on-disk page compression because decoding is almost free. ZFS exposes LZ4 as its fastest transparent compression mode. Network protocols (Apache Kafka, PostgreSQL) offer LZ4 as a wire-format option. It’s the "compress this, don’t care about ratio" default of modern systems engineering.
Technical Specifications
- MIME type
- application/x-lz4
- Extensions
- .lz4
- Algorithm
- LZ77 variant with fast byte-level parsing
- License
- BSD 2-Clause (library), GPL v2 (CLI)
- Typical integrations
- Linux kernel, ZFS, Kafka, RocksDB, Cassandra
Typical Sizes & Weights
Text file
40-60% of original
Already-compressed data (JPEG, MP4)
99%+ (no gain)
Database page (typical)
55-70% of original
STRENGTHS & LIMITATIONS.
Strengths
- Decompression speed — approaches memcpy throughput.
- Very fast compression — can keep up with SSD write speeds.
- Stable format — reference implementation unchanged for years.
- Widely deployed in databases, filesystems, and kernels.
- BSD-licensed library.
Limitations
- Compression ratio lags gzip by 20-30%.
- Not designed for long-term archival where ratio matters.
- Older than zstd, which beats LZ4 at comparable speed at slightly better ratio.
- Rare as a user-facing format — lives mostly inside databases and filesystems.
CURIOSITIES & TRIVIA.
LZ4 decompresses at roughly 4 GB/s per CPU core — faster than most SSDs can read data.
Yann Collet wrote LZ4 years before he designed Zstandard — both aimed at different trade-offs on the same speed-vs-ratio curve.
Linux kernel supports LZ4 for zram swap, which is why low-RAM systems (Raspberry Pi, Chromebooks) run better under pressure.
Apache Kafka, RocksDB, Cassandra, and ZFS all offer LZ4 as a transparent-compression option.
LZ4 is dual-licensed: BSD 2-Clause for the library, GPL v2 for the command-line tool — open for any use.
Specialized Utilities for .LZ4 Files
Compress Files to ZIP
Compress multiple files and folders into a single ZIP archive. Reduce total size for faster transfers and organized storage.
Compress Image to 50KB
Compress JPG, PNG, or WebP photos to strictly under 50 KB (50,000 bytes) for passport portals, university admissions, civil service forms, and KYC uploads without changing pixel dimensions.
Merge PDF
Combine multiple PDF files into a single document. Drag and drop to reorder pages before merging. No software installation required.
Compress PDF
Reduce PDF file size without visible quality loss. Choose from low, medium, or high compression levels. Ideal for email attachments and web uploads.
CONVERT FROM LZ4
Common Use Cases
Real-time compression, ZFS filesystem, game asset streaming, memory-mapped data
Related Formats
Popular comparisons
LZ4 vs ZIP
Differences, file size, and when to choose each format.
LZ4 vs 7Z
Differences, file size, and when to choose each format.
LZ4 vs TAR
Differences, file size, and when to choose each format.
LZ4 vs GZ
Differences, file size, and when to choose each format.
LZ4 vs BZ2
Differences, file size, and when to choose each format.
LZ4 vs XZ
Differences, file size, and when to choose each format.
Popular LZ4 conversions
The most-requested destinations when starting from LZ4.
Frequently Asked Questions
LZ4 (LZ4 Compressed) is an archive format used to bundle multiple files and folders into a single compressed file. The archive preserves the directory structure and typically reduces total size via compression. LZ4 sits in the archives & compressed family and has specific strengths around compression ratio, speed, or platform support.
7-Zip, WinRAR, The Unarchiver (macOS), and the built-in archive utilities on Windows and macOS open most LZ4 files. For command-line extraction, 7z, unar, or the format-specific tool handles LZ4 cleanly. If your extractor does not recognise LZ4, convert to ZIP first — ZIP opens on every operating system without extra software.
Upload the LZ4 to KaijuConverter and pick ZIP, 7Z, TAR.GZ, or RAR as the target. Our pipeline extracts the original archive and re-compresses the contents into the target format. File permissions, timestamps, and directory structure are preserved where both formats support them.
Depends on the goal. ZIP is the universal baseline — every OS extracts it out of the box. Formats like 7Z or TAR.GZ compress better but require specific tools. LZ4 may win on compression ratio, password support, or OS integration for specific workflows; ZIP wins on raw compatibility.
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