diff --git a/include/pocketpy/common/chunkedvector.h b/include/pocketpy/common/chunkedvector.h
new file mode 100644
index 00000000..f82f54db
--- /dev/null
+++ b/include/pocketpy/common/chunkedvector.h
@@ -0,0 +1,31 @@
+#pragma once
+
+#include "pocketpy/export.h"
+#include "pocketpy/common/vector.h"
+typedef struct c11_chunkedvector_chunk {
+    int length;
+    int capacity;
+    void* data;
+} c11_chunkedvector_chunk;
+
+typedef struct c11_chunkedvector {
+    c11_vector /*T=c11_chunkedvector_chunk*/ chunks;
+    int length;
+    int capacity;
+    int elem_size;
+    int initial_chunks;
+} c11_chunkedvector;
+
+// chunks[0]: size=1, total_capacity=1
+// chunks[1]: size=2, total_capacity=3
+// chunks[2]: size=4, total_capacity=7
+// chunks[3]: size=8, total_capacity=15
+// chunks[4]: size=16, total_capacity=31
+// chunks[5]: size=32, total_capacity=63
+// ...
+// chunks[n]: size=2^n, total_capacity=2^(n+1)-1
+
+void c11_chunkedvector__ctor(c11_chunkedvector* self, int elem_size, int initial_chunks);
+void c11_chunkedvector__dtor(c11_chunkedvector* self);
+void* c11_chunkedvector__emplace(c11_chunkedvector* self);
+void* c11_chunkedvector__at(c11_chunkedvector* self, int index);
\ No newline at end of file
diff --git a/src/common/chunkedvector.c b/src/common/chunkedvector.c
new file mode 100644
index 00000000..e6eedc0e
--- /dev/null
+++ b/src/common/chunkedvector.c
@@ -0,0 +1,86 @@
+#include "pocketpy/common/chunkedvector.h"
+
+#include <stdlib.h>
+#include <string.h>
+#include "pocketpy/common/utils.h"
+#include "pocketpy/config.h"
+
+#if defined(_MSC_VER)
+#include <intrin.h>
+#endif
+
+inline static int c11_bit_length(unsigned long x) {
+#if(defined(__clang__) || defined(__GNUC__))
+    return x == 0 ? 0 : (int)sizeof(unsigned long) * 8 - __builtin_clzl(x);
+#elif defined(_MSC_VER)
+    static_assert(sizeof(unsigned long) <= 4, "unsigned long is greater than 4 bytes");
+    unsigned long msb;
+    if(_BitScanReverse(&msb, x)) { return (int)msb + 1; }
+    return 0;
+#else
+    const int BIT_LENGTH_TABLE[32] = {0, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4,
+                                      5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5};
+    int msb = 0;
+    while(x >= 32) {
+        msb += 6;
+        x >>= 6;
+    }
+    msb += BIT_LENGTH_TABLE[x];
+    return msb;
+#endif
+}
+
+void c11_chunkedvector__ctor(c11_chunkedvector* self, int elem_size, int initial_chunks) {
+    if(initial_chunks < 5) initial_chunks = 5;
+    c11_vector__ctor(&self->chunks, sizeof(c11_chunkedvector_chunk));
+    self->length = 0;
+    self->capacity = (1U << (unsigned int)initial_chunks) - 1U;
+    self->elem_size = elem_size;
+    self->initial_chunks = initial_chunks;
+    void* chunks_data = PK_MALLOC(elem_size * ((1U << (unsigned int)initial_chunks) - 1));
+    for(int i = 0; i < initial_chunks; i++) {
+        // TODO: optimize?
+        c11_chunkedvector_chunk chunk = {.length = 0,
+                                         .capacity = 1U << i,
+                                         .data = (char*)chunks_data + elem_size * ((1U << i) - 1U)};
+        c11_vector__push(c11_chunkedvector_chunk, &self->chunks, chunk);
+    }
+}
+
+void c11_chunkedvector__dtor(c11_chunkedvector* self) {
+    for(int index = self->initial_chunks; index < self->chunks.length; index++) {
+        c11_chunkedvector_chunk* chunk = c11__at(c11_chunkedvector_chunk, &self->chunks, index);
+        PK_FREE(chunk->data);
+    }
+    c11_chunkedvector_chunk* initial_chunk = c11__at(c11_chunkedvector_chunk, &self->chunks, 0);
+    PK_FREE(initial_chunk->data);
+    c11_vector__dtor(&self->chunks);
+}
+
+void* c11_chunkedvector__emplace(c11_chunkedvector* self) {
+    if(self->length == self->capacity) {
+        #ifndef NDEBUG
+            c11_chunkedvector_chunk last_chunk = c11_vector__back(c11_chunkedvector_chunk, &self->chunks);
+            assert(last_chunk.capacity == last_chunk.length);
+        #endif
+        c11_chunkedvector_chunk chunk = {
+            .length = 0,
+            .capacity = 1U << (unsigned int)self->chunks.length,
+            .data = PK_MALLOC(self->elem_size * ((1U << (unsigned int)self->chunks.length)))};
+        self->capacity += chunk.capacity;
+        c11_vector__push(c11_chunkedvector_chunk, &self->chunks, chunk);
+    }
+    int last_chunk_index = c11_bit_length(self->length + 1) - 1;
+    c11_chunkedvector_chunk* last_chunk =
+        c11__at(c11_chunkedvector_chunk, &self->chunks, last_chunk_index);
+    void* p = (char*)last_chunk->data + self->elem_size * last_chunk->length;
+    last_chunk->length++;
+    self->length++;
+    return p;
+}
+
+void* c11_chunkedvector__at(c11_chunkedvector* self, int index) {
+    int chunk_index = c11_bit_length(index + 1) - 1;
+    c11_chunkedvector_chunk* chunk = c11__at(c11_chunkedvector_chunk, &self->chunks, chunk_index);
+    return (char*)chunk->data + (index + 1 - (1U << (unsigned int)chunk_index)) * self->elem_size;
+}