What Programming Language Is 7-Zip Written In?

This article explores the core programming languages behind 7-Zip, the popular open-source file archiver developed by Igor Pavlov. It covers the primary language used to build the software, the supporting languages utilized for hardware optimization, and the architectural reasons behind these choices.

The primary programming language of 7-Zip is C++.

The majority of 7-Zip’s codebase, including its graphical user interface (GUI), shell integration, archive management modules, and object-oriented framework, is written in C++. This allows the software to maintain an organized, modular architecture while interacting closely with the underlying operating system.

Supporting Languages

While C++ serves as the primary language, 7-Zip relies heavily on two other low-level languages to maximize performance:

C: The core compression and decompression algorithms, most notably the LZMA (Lempel-Ziv-Markov chain algorithm) and LZMA2 SDKs, are written largely in pure C. This ensures minimal overhead, straightforward memory management, and high portability across non-Windows platforms.
Assembly Language (ASM): Critical performance bottlenecks use hand-optimized Assembly routines. This includes code paths targeting x86 and x64 architectures for hardware-accelerated encryption (such as AES-NI) and cryptographic hashing (such as SHA-256 and CRC32).

Architectural Rationale

The combination of C++, C, and Assembly enables 7-Zip to achieve industry-leading compression ratios and speeds:

Direct Memory Control: By avoiding managed runtimes like Java or .NET, 7-Zip operates with direct pointer manipulation and minimal runtime overhead.
Resource Efficiency: The compiled executable has an exceptionally small footprint, consuming very little RAM when idle or performing basic tasks.
Cross-Platform Compatibility: Writing the core algorithms in standard C allows porting tools—such as the native Linux port of 7-Zip—to reuse the underlying compression libraries without major rewrites.