diff --git a/lib/std/core/cextern.kk b/lib/std/core/cextern.kk
new file mode 100644
index 000000000..1d932dc25
--- /dev/null
+++ b/lib/std/core/cextern.kk
@@ -0,0 +1,216 @@
+module std/core/cextern
+
+import std/num/int32
+import std/core/types
+import std/core/int
+
+extern import
+  c header-file "inline/cextern.h"
+
+// A managed koka pointer to C memory
+// Owned values can be freely passed around, captured in lambdas, escape their scope, etc.
+pub alias owned-c<t> = extern-owned<t>
+
+// A borrowed koka pointer to C memory during a scope s
+// Borrowed values are only guaranteed valid during their scope, should not escape the scope
+// For example an `owned-c<array<t>>` should only allow borrowed references to the middle of an array during a scope where the owned pointer will not be dropped
+pub alias borrowed-c<s::S,t> = extern-borrowed<t>
+
+// A raw pointer to C memory
+pub type c-pointer<t>
+
+// An opaque type to designate c-array types in Koka
+pub type c-array<t>
+
+// A type alias for a null pointer of type `t`
+pub alias c-null<t> = c-pointer<t>
+
+// The null pointer in C
+pub inline extern cnull(): c-null<t>
+  c inline "(intptr_t)0"
+
+// A null callback pointer
+pub val null-cb = 0.intptr_t
+
+// Needs to be extern otherwise, the compiler will optimize out the function and not keep the reference alive
+// Ensure that a reference is > 1 until after this point
+pub extern owned/keepalive(^s: owned-c<a>): <> ()
+  ""
+
+// Release a reference (decref an owned reference)
+pub fun owned/release(s: owned-c<a>): <> ()
+  ()
+
+// Retain a reference (incref an owned reference)
+pub extern owned/retain(s: owned-c<a>): <> ()
+  ""
+
+pub inline extern int/ptr<t>(i: intptr_t): c-pointer<t>
+  c inline "(intptr_t)#1"
+
+pub inline extern carray/intptr<t>(c: c-array<t>): intptr_t
+  c inline "#1"
+
+pub inline extern carray/ptr<t>(c: c-array<t>): c-pointer<t>
+  c inline "#1"
+
+pub inline extern intptr/carray<t>(c: intptr_t): c-array<t>
+  c inline "#1"
+
+pub inline extern ptr/carray<t>(c: c-pointer<t>): c-array<t>
+  c inline "#1"
+
+// Allow casting between different types of pointers
+pub inline extern unsafe/cptr-cast<s>(c: c-pointer<t>): c-pointer<s>
+  c inline "#1"
+
+// Allocate `n*size-of` bytes of memory using kk_malloc and return a pointer to the allocated memory
+inline extern int/malloc<t>(n: int32, size-of: int32): c-pointer<t>
+  c inline "(kk_addr_t)kk_malloc(#1*#2, kk_context())"
+
+// Allocate `n*size-of` bytes of memory using C's malloc and return a pointer to the allocated memory
+inline extern int/malloc-c<t>(n: int32, size-of: int32): c-pointer<t>
+  c inline "(kk_addr_t)malloc(#1*#2)"
+
+// Allocate a single element of type `t` using `kk_malloc` and return a managed pointer
+// Type `t` should:
+// - Be an opaque type in Koka corresponding to a C type (e.g. `pub type cstruct` with no members)
+// - Have a `size-of` function that returns the size of the structure in bytes
+pub inline fun single/malloc<t>(?size-of: (c-null<t>) -> int32): owned-c<t>
+  int/malloc(1.int32, size-of(cnull())).c-own-extern
+
+// Allocate `n` elements of type `t` using `kk_malloc` and return a managed pointer to the array
+// Type `t` should:
+// - Be an opaque type in Koka corresponding to a C type (e.g. `pub type cstruct` with no members)
+// - Have a `size-of` function that returns the size of the structure in bytes
+pub inline fun array/malloc<t>(n: int32, ?size-of: (c-null<t>) -> int32): owned-c<c-array<t>>
+  int/malloc(n, size-of(cnull())).c-own-extern
+
+// Allocate a single element of type `t` using C's `malloc` and return a managed pointer
+// Type `t` should:
+// - Be an opaque type in Koka corresponding to a C type (e.g. `pub type cstruct` with no members)
+// - Have a `size-of` function that returns the size of the structure in bytes
+pub inline fun single/malloc-c<t>(?size-of: (c-null<t>) -> int32): owned-c<t>
+  int/malloc-c(1.int32, size-of(cnull())).c-own-free-calloc-extern
+
+// Allocate `n` elements of type `t` using C's `malloc` and return a managed pointer to the array
+// Type `t` should:
+// - Be an opaque type in Koka corresponding to a C type (e.g. `pub type cstruct` with no members)
+// - Have a `size-of` function that returns the size of the structure in bytes
+pub inline fun array/malloc-c<t>(n: int32, ?size-of: (c-null<t>) -> int32): owned-c<c-array<t>>
+  int/malloc-c(n, size-of(cnull())).c-own-free-calloc-extern
+
+// !!!WARNING!!! UNSAFE API
+// Allocate `n` elements of type `t` using `kk_malloc` and return a managed pointer to the array
+// Type `t` should:
+// - Be an opaque type in Koka corresponding to a C type (e.g. `pub type cstruct` with no members)
+// - Have a `size-of` function that returns the size of the structure in bytes
+//
+// NOTES:
+// Prefer using `array/malloc` or `single/malloc` instead of this function which return a managed pointer.
+// Raw `c-pointer<t>` should be used in low-level generated koka ffi functions since the pointer is unknown to be managed or not.
+// Conversion routines for `owned-c<t>` and `borrowed-c<s,t>` then should be used to get the raw pointers to be used in the ffi functions
+// Higher level apis to c libraries should then provide an interface using `owned-c<t>` and `borrowed-c<s,t>` instead of `c-pointer<t>`
+pub inline fun ptr/unsafe-malloc<t>(n: int32, ?size-of: (c-null<t>) -> int32): c-pointer<t>
+  int/malloc(n, size-of(cnull()))
+
+// !!!WARNING!!! UNSAFE API
+// Allocate `n` elements of type `t` using C's `malloc` and return a managed pointer to the array
+// Type `t` should:
+// - Be an opaque type in Koka corresponding to a C type (e.g. `pub type cstruct` with no members)
+// - Have a `size-of` function that returns the size of the structure in bytes
+//
+// NOTES:
+// Prefer using `array/malloc-c` or `single/malloc-c` instead of this function which return a managed pointer.
+// Raw `c-pointer<t>` should be used in low-level generated koka ffi functions since the pointer is unknown to be managed or not.
+// Conversion routines for `owned-c<t>` and `borrowed-c<s,t>` then should be used to get the raw pointers to be used in the ffi functions
+// Higher level apis to c libraries should then provide an interface using `owned-c<t>` and `borrowed-c<s,t>` instead of `c-pointer<t>`
+pub inline fun ptr/unsafe-malloc-c<t>(n: int32, ?size-of: (c-null<t>) -> int32): c-pointer<t>
+  int/malloc-c(n, size-of(cnull()))
+
+// Transform a C ptr into a managed koka value, which will be freed by `kk_free` when koka's reference count reaches 0
+inline extern c-own-extern(c: c-pointer<a>): owned-c<a>
+  c inline "kk_cptr_raw_box(&kk_free_fun, (void *)#1, kk_context())"
+
+// Transform a C ptr into a managed koka value, which will be freed by C's `free` when koka's reference count reaches 0
+inline extern c-own-free-calloc-extern(c: c-pointer<a>): owned-c<a>
+  c inline "kk_cptr_raw_box(&kk_free_calloc, (void *)#1, kk_context())"
+
+// Transform a C ptr `c` into a koka value that holds the c reference without freeing it
+// The pointer should be valid for the duration of the callback `f`.
+inline extern c-borrow(c: c-pointer<t>, f: forall<s> borrowed-c<s,t> -> e a): e a
+  c "kk_borrow_ptr"
+
+// !!!WARNING!!!: Extremely unsafe API (needed for `c-borrow`), get approval to use anywhere else.
+inline extern unsafe-cast<s>(b: c-pointer<t>): borrowed-c<s,t>
+  c inline "#1"
+
+// Transform an unmanaged C ptr into a managed koka reference to C memory
+// Ensure the pointer is not going to be freed by C code, otherwise use `c-borrow` instead
+// Also ensure the memory was allocated using `kk_malloc`
+pub inline fun c-own<t>(t: c-pointer<t>): owned-c<t>
+  t.c-own-extern
+
+// Transform an unmanaged C ptr into a managed koka reference to C memory
+// Ensure the pointer is not going to be freed by C code, otherwise use `c-borrow` instead
+// Also ensure the memory was allocated using C's `malloc`
+pub fun c-own-free-calloc<t>(t: c-pointer<t>): owned-c<t>
+  t.c-own-free-calloc-extern
+
+// Transform a koka `owned-c` managed pointer into a C ptr 
+// Keeps the koka reference alive during the scope of the callback `f`
+pub inline extern owned/with-ptr(^t: owned-c<t>, f: c-pointer<t> -> e a): e a
+  c "kk_owned_with_ptr"
+
+// Transform a koka `borrowed-c` managed pointer into a C ptr
+// Keeps the koka reference alive during the scope of the callback `f`
+pub inline extern borrowed/with-ptr(^t: borrowed-c<s,t>, f: c-pointer<t> -> e a): e a
+  c "kk_borrowed_with_ptr"
+
+// !!!WARNING!!! Extremely UNSAFE API
+// Get the raw C pointer from a `borrowed-c` managed pointer to use immediately in an ffi function
+// This doesn't return a typed pointer, and accepts any boxed type as input, so it is very dangerous
+//   Use `borrowed/with-ptr` most of the time and
+//       `borrow/use-ffi-ptr` if directly passing to an safe ffi call
+pub inline extern unsafe-borrowed-ffi-ptr-extern<t>(c: borrowed-c<s,t>): c-pointer<t>
+  c inline "(kk_addr_t)kk_cptr_unbox_borrowed(#1, kk_context())"
+
+// !!!WARNING!!! UNSAFE API
+// Get the raw C pointer from an `borrowed-c` managed pointer to use immediately in an ffi function
+// Not safe to pass around Koka code
+// However, since an immediate use is still within the scope of the `borrowed-c` it is safe
+//   This is due borrowed pointers being guaranteed to be valid during their whole scope (the lambda enclosing the call to this method) 
+//   A similar api for `owned-c` is not possible since converting an owned pointer to a raw pointer could allow the owned pointer to be freed if this was its last use
+//   For owned pointers use `owned/with-ptr` instead
+pub inline fun borrow/use-ffi-ptr<t>(c: borrowed-c<s,t>): c-pointer<t>
+  c.unsafe-borrowed-ffi-ptr-extern
+
+// Transform a koka `owned-c` managed pointer to an array into a C ptr pointing to the element at index `idx` of type `t` and size `size-of(cnull())`
+// Keeps the koka reference alive during the scope of the callback `f`
+// This is guaranteed due to be this being an external function (`f` is not inlineable), and `t` being borrowed
+pub inline extern offset/with-ptr(^t: owned-c<c-array<t>>, idx: ssize_t, f: c-pointer<t> -> e a, size-of: int32): e a
+  c "kk_owned_with_ptr_idx"
+
+// Transform a koka `owned-c` managed pointer to an array into a C ptr pointing to the element at index `idx` of type `t` and size `size-of(cnull())`
+// Keeps the koka reference alive during the scope of the callback `f`
+pub inline fun c-array/with-ptr(t: owned-c<c-array<t>>, idx: ssize_t, f: forall<s> borrowed-c<s,t> -> e a, ?size-of: (c-null<t>) -> int32): e a
+  offset/with-ptr(t, idx, fn(p) c-borrow(p, f), size-of(cnull()))
+
+// Transform an assumed pointer to a C string into a Koka string
+// Copies the memory
+pub inline extern ptr/to-string(ptr: c-pointer<int8>): string
+  c inline "kk_string_alloc_raw((const char *)#1, false, kk_context())"
+
+// Transform an assumed pointer to a C string of length len into a Koka string
+// Copies the memory
+// Assume the array is non-null terminated and adds the terminating character
+pub inline extern strlen-ptr/to-string(ptr: c-pointer<int8>, len: int64): string
+  c inline "kk_string_alloc_raw_buff(#2, (char *)#1, false, kk_context())"
+
+// Borrows the c pointer to a koka managed string for the duration of the callback `f`
+inline extern ptr/with-c-string(^s: string, f: c-pointer<int8> -> e a): e a
+  c "kk_with_c_string"
+
+// Borrows the c pointer to a koka managed string for the duration of the callback `f`
+pub inline fun cptr/with-c-string(^s: string, f: forall<s> borrowed-c<s,int8> -> e a): e a
+  with-c-string(s, fn(p) c-borrow(p, f))
diff --git a/lib/std/core/inline/cextern.h b/lib/std/core/inline/cextern.h
new file mode 100644
index 000000000..babb042d6
--- /dev/null
+++ b/lib/std/core/inline/cextern.h
@@ -0,0 +1,37 @@
+// free memory using default C allocator
+static void kk_free_calloc(void* p, kk_block_t* b, kk_context_t* _ctx) {
+  kk_unused(b);
+  kk_unused(_ctx);
+  free(p);
+}
+
+static kk_box_t kk_owned_with_ptr(kk_box_t owned, kk_function_t f, kk_context_t* _ctx) {
+  kk_addr_t cptr = (kk_addr_t)kk_cptr_raw_unbox_borrowed(owned, kk_context());
+  return kk_function_call(kk_box_t,(kk_function_t,kk_addr_t,kk_context_t*), f, (f, cptr, kk_context()), kk_context());
+}
+
+static kk_box_t kk_borrowed_with_ptr(kk_box_t borrowed, kk_function_t f, kk_context_t* _ctx) {
+  kk_addr_t cptr = (kk_addr_t)kk_cptr_unbox_borrowed(borrowed, kk_context());
+  return kk_function_call(kk_box_t,(kk_function_t,kk_addr_t,kk_context_t*), f, (f, cptr, kk_context()), kk_context());
+}
+
+static kk_box_t kk_borrow_ptr(kk_addr_t cptr, kk_function_t f, kk_context_t* _ctx) {
+  kk_box_t ptr = kk_cptr_box((void *)cptr, kk_context());
+  return kk_function_call(kk_box_t,(kk_function_t,kk_box_t,kk_context_t*), f, (f, ptr, kk_context()), kk_context());
+}
+
+static kk_box_t kk_owned_with_ptr_idx(kk_box_t owned, kk_ssize_t idx, kk_function_t f, int32_t size, kk_context_t* _ctx) {
+  uint8_t* cptr = (uint8_t*)kk_cptr_raw_unbox_borrowed(owned, kk_context());
+  kk_addr_t cptr_idx = (kk_addr_t)(cptr + (idx*size));
+  return kk_function_call(kk_box_t,(kk_function_t,kk_addr_t,kk_context_t*), f, (f, cptr_idx, kk_context()), kk_context());
+}
+
+static kk_string_t kk_string_alloc_raw_buff(kk_ssize_t len, char* s, bool free, kk_context_t* ctx){
+  s[len] = 0;
+  return kk_string_alloc_raw_len(len, s, free, ctx);
+}
+
+static kk_box_t kk_with_c_string(kk_string_t s, kk_function_t f, kk_context_t* _ctx){
+  kk_addr_t cptr = (kk_addr_t)kk_string_cbuf_borrow(s, NULL, kk_context());
+  return kk_function_call(kk_box_t,(kk_function_t,kk_addr_t,kk_context_t*), f, (f, cptr, kk_context()), kk_context());
+}
\ No newline at end of file
diff --git a/lib/std/core/types.kk b/lib/std/core/types.kk
index 079fc4e17..670b3f2ed 100644
--- a/lib/std/core/types.kk
+++ b/lib/std/core/types.kk
@@ -101,6 +101,12 @@ pub value type float32
 // See `module std/core/vector` for vector operations.
 pub type vector<a>
 
+// The type of an external (i.e. C) value where the memory is owned and managed by koka's refcounting
+pub ref type extern-owned<t>
+
+// The type of an external (i.e. C) value where the memory is borrowed and managed by external code
+pub ref type extern-borrowed<t>
+
 // An any type. Used for external calls.
 pub type any
 
diff --git a/src/Backend/C/Box.hs b/src/Backend/C/Box.hs
index 638ab2200..9eb85137e 100644
--- a/src/Backend/C/Box.hs
+++ b/src/Backend/C/Box.hs
@@ -367,6 +367,7 @@ cType tp
         -> CFun (map (cType . snd) pars) (cType res)
       TApp t ts
         -> cType t
+      TCon (TypeCon nm _) | nm == nameTpExternOwned || nm == nameTpExternBorrowed -> CBox
       TCon c
         -> CData
       TVar v
diff --git a/src/Backend/C/FromCore.hs b/src/Backend/C/FromCore.hs
index 01fb96ae5..06f2cf47f 100644
--- a/src/Backend/C/FromCore.hs
+++ b/src/Backend/C/FromCore.hs
@@ -1292,6 +1292,10 @@ cTypeCon c
          then CPrim "kk_integer_t"
         else if (name == nameTpString)
          then CPrim "kk_string_t"
+        else if (name == nameTpExternOwned)
+         then CPrim "kk_box_t"
+        else if (name == nameTpExternBorrowed)
+         then CPrim "kk_box_t"
         else if (name == nameTpVector)
          then CPrim "kk_vector_t"
         else if (name ==  nameTpEvv)
@@ -1302,6 +1306,10 @@ cTypeCon c
          then CPrim "kk_ssize_t"
         else if (name == nameTpIntPtrT)
          then CPrim "intptr_t"
+        else if (name == nameTpCPointer)
+         then CPrim "intptr_t"
+        else if (name == nameTpCArray)
+         then CPrim "intptr_t"
         else if (name == nameTpFloat)
          then CPrim "double"
         else if (name == nameTpBool)
diff --git a/src/Backend/C/Parc.hs b/src/Backend/C/Parc.hs
index 1319c32ae..47e0db85b 100644
--- a/src/Backend/C/Parc.hs
+++ b/src/Backend/C/Parc.hs
@@ -1029,7 +1029,7 @@ extractDataDefType tp
 
 
 isBoxType :: Type -> Bool
-isBoxType (TCon (TypeCon name _))  = name == nameTpBox
+isBoxType (TCon (TypeCon name _))  = name == nameTpBox || name == nameTpExternBorrowed || name == nameTpExternOwned
 isBoxType (TVar _)                 = True
 isBoxType (TSyn _ _ tp)            = isBoxType tp
 isBoxType (TApp tp _)              = isBoxType tp
diff --git a/src/Common/NamePrim.hs b/src/Common/NamePrim.hs
index b5950799b..86e06f665 100644
--- a/src/Common/NamePrim.hs
+++ b/src/Common/NamePrim.hs
@@ -125,6 +125,7 @@ module Common.NamePrim
           , makeTpHandled
           , nameTpHandled, nameTpHandled1, nameTpNHandled, nameTpNHandled1
           , nameTpMarker
+          , nameTpExternOwned, nameTpExternBorrowed, nameTpCPointer, nameTpCArray
           {-
           , nameTpOperation, nameYieldOp
           , nameTpCps, nameTpYld, nameTpCont
@@ -376,6 +377,11 @@ nameByref       = coreTypesName "@byref"
 namePredHeapDiv = coreTypesName "hdiv"
 namePredEffDiv  = coreTypesName "ediv"
 
+nameTpCPointer    = qualify (newModuleName "std/core/cextern") (newName "c-pointer")
+nameTpCArray    = qualify (newModuleName "std/core/cextern") (newName "c-array")
+nameTpExternOwned    = coreTypesName "extern-owned"
+nameTpExternBorrowed = coreTypesName "extern-borrowed"
+
 nameTpRef       = coreTypesName "ref"
 nameTpLocalVar  = coreTypesName "local-var"
 nameTpLocal     = coreTypesName "local"
diff --git a/test/cgen/extern.h b/test/cgen/extern.h
new file mode 100644
index 000000000..1635efb8c
--- /dev/null
+++ b/test/cgen/extern.h
@@ -0,0 +1,3 @@
+typedef struct c_struct_s {
+  int xint;
+} c_struct_t;
\ No newline at end of file
diff --git a/test/cgen/extern.kk b/test/cgen/extern.kk
new file mode 100644
index 000000000..9b86bcc0a
--- /dev/null
+++ b/test/cgen/extern.kk
@@ -0,0 +1,60 @@
+import std/core/cextern
+import std/num/int32
+
+extern import
+  c file "extern.h"
+
+pub type c-struct;
+pub alias kstructo = owned-c<c-struct>;
+pub alias kstructoa = owned-c<c-array<c-struct>>;
+pub alias kstructb<s> = borrowed-c<s,c-struct>;
+
+pub extern size-of(c: c-null<c-struct>): int32
+  c inline "sizeof(c_struct_t)"
+
+inline extern ptr/xint(s: c-pointer<c-struct>): int32
+  c inline "((c_struct_t*)#1)->xint"
+ 
+inline extern ptr/set-xint(s: c-pointer<c-struct>, x: int32): ()
+  c inline "((c_struct_t*)#1)->xint = #2"
+
+pub fun kstructo(): kstructo
+  malloc()
+
+pub fun kstructoc(): kstructo
+  malloc-c()
+
+pub fun kstruct-array(n: int): kstructoa
+  malloc(n.int32)
+
+pub inline fun kstruct/xint(^s: kstructo): int32
+  s.with-ptr(xint)
+
+pub inline fun kstructb/xint(^s: kstructb<s>): int32
+  s.with-ptr(xint)
+
+pub fun set-xintf(x: int32): ((c-pointer<c-struct>) -> ())
+  fn(p) set-xint(p, x)
+
+pub inline fun kstruct/set-xint(^s: kstructo, x: int32): ()
+  s.with-ptr(set-xintf(x))
+
+pub inline fun kstructb/set-xint(^s: kstructb<s>, x: int32): ()
+  s.with-ptr(set-xintf(x))
+
+fun main()
+  val s = kstructo()
+  set-xint(s, 42.int32)
+  println(xint(s))
+
+  val s2 = kstructoc()
+  set-xint(s2, 43.int32)
+  println(xint(s2))
+
+  val ss = kstruct-array(10)
+  for(10) fn(i)
+    ss.with-ptr(i.ssize_t) fn(b)
+      b.set-xint(i.int32)
+  for(10) fn(i)
+    ss.with-ptr(i.ssize_t) fn(b)
+      println(b.xint)