You might me wondering whether C is still used in 2025 or not. The answer is yes; C is still used today in many software systems. It remains a cornerstone of the software world. Operating system kernels like Linux, Windows, and various embedded and real-time systems rely heavily on C for its direct control over hardware resources, stable performance characteristics, and minimal runtime overhead. Modern compilers and interpreters often choose C as an implementation vehicle, leveraging its ability to produce efficient, portable executables that serve as a widely accepted “lowest common denominator” on diverse hardware platforms.
The language’s influence extends beyond traditional system-level software. In domains like embedded development—where memory and processing constraints are stringent—C’s predictable behavior and small footprint remain crucial. Manufacturers of microcontrollers, IoT devices, and automotive control units rely on well-tested, certified C code to ensure safety, correctness, and compliance with industry standards.
C continues to guide the development of new languages and libraries. Modern languages often adopt or adapt C’s calling conventions, data types, and binary interfaces to achieve interoperability. This ensures that existing C codebases, toolchains, and libraries can be seamlessly integrated into new software stacks. The widespread presence of C Application Programming Interfaces (APIs) in operating systems, graphical toolkits, and networking frameworks allows developers, regardless of their chosen programming language, to tap into mature functionality.
Furthermore, the discipline required by C’s minimal abstractions encourages developers to deeply understand underlying hardware and memory management concepts. While higher-level languages often obscure these details, learning and using C provides insights into the building blocks of computing. For performance-critical tasks—such as cryptographic processing, signal analysis, real-time data handling, or rendering loops in game engines—C remains an enduring choice due to its reliability, predictability, and the widespread availability of optimizing compilers.
Below are several prominent examples of software systems that rely heavily on C for performance, portability, and direct access to hardware-level functionality. Each case highlights why C remains critical in modern computing environments.
Primarily written in C, the Linux kernel manages process scheduling, memory allocation, device drivers, and file systems on millions of servers, desktops, and embedded devices. Its use of C ensures efficient resource management and broad compatibility across diverse hardware platforms.
Although Windows includes code in various languages, many low-level and performance-critical parts of the Windows operating system are implemented in C. This choice enables fine-grained hardware interaction and stable, long-term maintenance of core system functionalities.
Routers, switches, and network appliances often use C-based firmware and protocol implementations. C’s efficiency ensures that data packets are processed with minimal latency, critical for meeting the demands of high-speed internet infrastructure and telecommunications networks.
SQLite, a popular lightweight database engine used in countless applications (from mobile apps to embedded devices), is implemented in C. Its compact size, reliability, and speed stem from C’s efficient use of memory and direct control over database file formats.
Performance-intensive parts of popular browsers—such as rendering engines, networking layers, and cryptography libraries—are frequently C-based. This approach ensures that web pages render quickly, and secure connections are established efficiently across multiple platforms.
FFmpeg, a widely used multimedia framework for video and audio processing, is predominantly written in C. It delivers high-performance encoding, decoding, and streaming capabilities while maintaining portability across a multitude of devices and operating systems.
Specialized RTOS kernels found in factory automation, robotics, and avionics are often coded in C. The language’s deterministic execution and fine-grained memory control allow these systems to meet strict timing constraints and run reliably for extended periods without failure.
HPC applications and scientific computation libraries (e.g., BLAS, LAPACK) often use C or C-interfaced routines to achieve low-level optimization on supercomputers. This ensures predictable performance and the ability to hand-tune code for particular processors or accelerators.
Below are several well-established C libraries widely used in the astronomy community. Each provides specific capabilities—from reading astrophysical data files to handling celestial coordinate transformations—and is maintained by reputable institutions or projects.
