diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 5ac7f77..4779daa 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -11,7 +11,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ubuntu-latest, macos-latest]
+        os: [ubuntu-latest, macos-latest, windows-latest]
         build_type: [Debug, Release]
         include:
           - os: ubuntu-latest
@@ -20,6 +20,9 @@ jobs:
           - os: macos-latest
             cc: clang
             cxx: clang++
+          - os: windows-latest
+            cc: cl
+            cxx: cl
 
     runs-on: ${{ matrix.os }}
 
@@ -39,12 +42,25 @@ jobs:
           brew install clang-format zstd libsodium || true
           # cmake is already available on macOS runners
 
+      - name: Install dependencies (Windows)
+        if: matrix.os == 'windows-latest'
+        run: |
+          # Install vcpkg dependencies
+          vcpkg install zstd:x64-windows libsodium:x64-windows
+          # Visual Studio Build Tools are already available
+
       - name: Set up environment
         run: |
           echo "CC=${{ matrix.cc }}" >> $GITHUB_ENV
           echo "CXX=${{ matrix.cxx }}" >> $GITHUB_ENV
 
-      - name: Configure CMake
+      - name: Configure CMake (Windows)
+        if: matrix.os == 'windows-latest'
+        shell: cmd
+        run: cmake -B build -DCMAKE_BUILD_TYPE=${{ matrix.build_type }} -DCMAKE_TOOLCHAIN_FILE=C:/vcpkg/scripts/buildsystems/vcpkg.cmake -DBFC_WITH_ZSTD=ON -DBFC_WITH_SODIUM=ON
+
+      - name: Configure CMake (Unix)
+        if: matrix.os != 'windows-latest'
         run: |
           cmake -B build \
             -DCMAKE_BUILD_TYPE=${{ matrix.build_type }} \
@@ -53,16 +69,30 @@ jobs:
             -DBFC_WITH_ZSTD=ON \
             -DBFC_WITH_SODIUM=ON
 
-      - name: Build
+      - name: Build (Windows)
+        if: matrix.os == 'windows-latest'
+        shell: cmd
+        run: cmake --build build --config ${{ matrix.build_type }} --parallel
+
+      - name: Build (Unix)
+        if: matrix.os != 'windows-latest'
         run: cmake --build build --config ${{ matrix.build_type }} -j$(nproc 2>/dev/null || sysctl -n hw.ncpu)
 
-      - name: Run tests
-        if: matrix.build_type == 'Debug'
+      - name: Run tests (Windows)
+        if: matrix.build_type == 'Debug' && matrix.os == 'windows-latest'
+        shell: cmd
+        run: |
+          cd build
+          ctest --output-on-failure --parallel --config ${{ matrix.build_type }}
+
+      - name: Run tests (Unix)
+        if: matrix.build_type == 'Debug' && matrix.os != 'windows-latest'
         run: |
           cd build
           ctest --output-on-failure --parallel $(nproc 2>/dev/null || sysctl -n hw.ncpu)
 
       - name: Test CLI functionality
+        if: matrix.os != 'windows-latest'
         run: |
           # Create test data
           mkdir -p test_data
@@ -219,6 +249,7 @@ jobs:
           rm -rf test_encrypted.bfc test_keyfile.bfc test_enc_comp.bfc test.key
 
       - name: Run benchmarks
+        if: matrix.os != 'windows-latest'
         run: |
           cd build/benchmarks
           ./benchmark_crc32c
diff --git a/src/lib/bfc_crc32c.c b/src/lib/bfc_crc32c.c
index c3e8ea9..5fbbe4e 100644
--- a/src/lib/bfc_crc32c.c
+++ b/src/lib/bfc_crc32c.c
@@ -19,7 +19,11 @@
 #include <string.h>
 
 #if defined(__x86_64__) || defined(_M_X64)
+#ifdef _WIN32
+#include <intrin.h>
+#else
 #include <cpuid.h>
+#endif
 #include <immintrin.h>
 #define HAS_X86_64 1
 #elif defined(__aarch64__) || defined(_M_ARM64)
@@ -52,10 +56,17 @@ static void init_crc32c_table(void) {
 #ifdef HAS_X86_64
 static int detect_sse42_support(void) {
   unsigned int eax, ebx, ecx, edx;
+#ifdef _WIN32
+  int cpuinfo[4];
+  __cpuid(cpuinfo, 1);
+  ecx = cpuinfo[2];
+  return (ecx & (1 << 20)) != 0; // SSE4.2 bit
+#else
   if (__get_cpuid(1, &eax, &ebx, &ecx, &edx)) {
     return (ecx & bit_SSE4_2) != 0;
   }
   return 0;
+#endif
 }
 
 static uint32_t crc32c_hw_x86(uint32_t crc, const void* data, size_t len) {
diff --git a/src/lib/bfc_os.h b/src/lib/bfc_os.h
index 7ccac47..b24ff04 100644
--- a/src/lib/bfc_os.h
+++ b/src/lib/bfc_os.h
@@ -21,7 +21,17 @@
 #include <stdio.h>
 
 #ifdef _WIN32
+#define WIN32_LEAN_AND_MEAN
+#include <sys/stat.h>
 #include <windows.h>
+// Define missing POSIX constants for Windows
+#ifndef S_IFLNK
+#define S_IFLNK 0120000 // Symbolic link file type
+#endif
+// Define missing POSIX types for Windows
+#ifndef ssize_t
+typedef SSIZE_T ssize_t;
+#endif
 #else
 #include <sys/types.h>
 #include <unistd.h>
diff --git a/src/lib/bfc_reader.c b/src/lib/bfc_reader.c
index 7e842ab..4571f96 100644
--- a/src/lib/bfc_reader.c
+++ b/src/lib/bfc_reader.c
@@ -25,7 +25,12 @@
 #include <stdlib.h>
 #include <string.h>
 #include <sys/stat.h>
+#ifdef _WIN32
+#include <io.h>
+#define access _access
+#else
 #include <unistd.h>
+#endif
 
 #define READ_BUFFER_SIZE 65536