diff --git a/include/pocketpy/common/str.h b/include/pocketpy/common/str.h
index 41bf3e85..c1fee572 100644
--- a/include/pocketpy/common/str.h
+++ b/include/pocketpy/common/str.h
@@ -42,7 +42,6 @@ void c11_string__ctor2(c11_string* self, const char* data, int size);
 c11_string* c11_string__copy(c11_string* self);
 void c11_string__delete(c11_string* self);
 c11_sv c11_string__sv(c11_string* self);
-c11_string* c11_string__replace(c11_string* self, char old, char new_);
 
 int c11_string__u8_length(c11_string* self);
 c11_sv c11_string__u8_getitem(c11_string* self, int i);
@@ -56,6 +55,9 @@ int c11_sv__index(c11_sv self, char c);
 int c11_sv__index2(c11_sv self, c11_sv sub, int start);
 int c11_sv__count(c11_sv self, c11_sv sub);
 
+c11_string* c11_sv__replace(c11_sv self, char old, char new_);
+c11_string* c11_sv__replace2(c11_sv self, c11_sv old, c11_sv new_);
+
 c11_vector/* T=c11_sv */ c11_sv__split(c11_sv self, char sep);
 c11_vector/* T=c11_sv */ c11_sv__split2(c11_sv self, c11_sv sep);
 
diff --git a/include/pocketpy/interpreter/vm.h b/include/pocketpy/interpreter/vm.h
index 8eca55ed..23ef009c 100644
--- a/include/pocketpy/interpreter/vm.h
+++ b/include/pocketpy/interpreter/vm.h
@@ -70,6 +70,9 @@ void pk_VM__dtor(pk_VM* self);
 void pk_VM__push_frame(pk_VM* self, Frame* frame);
 void pk_VM__pop_frame(pk_VM* self);
 
+bool pk__parse_int_slice(const py_Ref slice, int length, int* start, int* stop, int* step);
+bool pk__normalize_index(int* index, int length);
+
 typedef enum pk_FrameResult {
     RES_RETURN,
     RES_CALL,
diff --git a/include/pocketpy/pocketpy.h b/include/pocketpy/pocketpy.h
index e93d107f..db3ec960 100644
--- a/include/pocketpy/pocketpy.h
+++ b/include/pocketpy/pocketpy.h
@@ -296,6 +296,7 @@ bool py_str(py_Ref val);
 py_GlobalRef py_retval();
 
 #define py_isnil(self) ((self)->type == 0)
+#define py_isnone(self) ((self)->type == tp_none_type)
 
 /* tuple */
 
@@ -334,6 +335,11 @@ const char* py_tpname(py_Type type);
 /// Check if the object is an instance of the given type.
 bool py_checktype(const py_Ref self, py_Type type);
 
+#define py_checkint(self) py_checktype(self, tp_int)
+#define py_checkfloat(self) py_checktype(self, tp_float)
+#define py_checkbool(self) py_checktype(self, tp_bool)
+#define py_checkstr(self) py_checktype(self, tp_str)
+
 int py_replinput(char* buf);
 
 /// Python favored string formatting.
diff --git a/src/common/str.c b/src/common/str.c
index b205198e..9441112a 100644
--- a/src/common/str.c
+++ b/src/common/str.c
@@ -38,8 +38,8 @@ void c11_string__delete(c11_string* self) { free(self); }
 
 c11_sv c11_string__sv(c11_string* self) { return (c11_sv){self->data, self->size}; }
 
-c11_string* c11_string__replace(c11_string* self, char old, char new_) {
-    c11_string* retval = c11_string__copy(self);
+c11_string* c11_sv__replace(c11_sv self, char old, char new_) {
+    c11_string* retval = c11_string__new2(self.data, self.size);
     char* p = (char*)retval->data;
     for(int i = 0; i < retval->size; i++) {
         if(p[i] == old) p[i] = new_;
@@ -47,6 +47,23 @@ c11_string* c11_string__replace(c11_string* self, char old, char new_) {
     return retval;
 }
 
+c11_string* c11_sv__replace2(c11_sv self, c11_sv old, c11_sv new_){
+    c11_sbuf buf;
+    c11_sbuf__ctor(&buf);
+    int start = 0;
+    while(true) {
+        int i = c11_sv__index2(self, old, start);
+        if(i == -1) break;
+        c11_sv tmp = c11_sv__slice2(self, start, i);
+        c11_sbuf__write_sv(&buf, tmp);
+        c11_sbuf__write_sv(&buf, new_);
+        start = i + old.size;
+    }
+    c11_sv tmp = c11_sv__slice2(self, start, self.size);
+    c11_sbuf__write_sv(&buf, tmp);
+    return c11_sbuf__submit(&buf);
+}
+
 int c11_string__u8_length(c11_string* self) {
     return c11__byte_index_to_unicode(self->data, self->size);
 }
diff --git a/src/interpreter/ceval.c b/src/interpreter/ceval.c
index 8470e4c3..4c6d4da0 100644
--- a/src/interpreter/ceval.c
+++ b/src/interpreter/ceval.c
@@ -753,5 +753,7 @@ bool py_binaryop(const py_Ref lhs, const py_Ref rhs, py_Name op, py_Name rop) {
     pk_VM* self = pk_current_vm;
     PUSH(lhs);
     PUSH(rhs);
-    return stack_binaryop(self, op, rop);
+    bool ok = stack_binaryop(self, op, rop);
+    STACK_SHRINK(2);
+    return ok;
 }
\ No newline at end of file
diff --git a/src/interpreter/vm.c b/src/interpreter/vm.c
index 394139ac..db7ab432 100644
--- a/src/interpreter/vm.c
+++ b/src/interpreter/vm.c
@@ -189,6 +189,70 @@ void pk_VM__pop_frame(pk_VM* self) {
     Frame__delete(frame);
 }
 
+static void _clip_int(int* value, int min, int max) {
+    if(*value < min) *value = min;
+    if(*value > max) *value = max;
+}
+
+bool pk__parse_int_slice(const py_Ref slice, int length, int* start, int* stop, int* step) {
+    py_Ref s_start = py_getslot(slice, 0);
+    py_Ref s_stop = py_getslot(slice, 1);
+    py_Ref s_step = py_getslot(slice, 2);
+
+    if(py_isnone(s_step))
+        *step = 1;
+    else {
+        if(!py_checkint(s_step)) return false;
+        *step = py_toint(s_step);
+    }
+    if(*step == 0) return ValueError("slice step cannot be zero");
+
+    if(*step > 0) {
+        if(py_isnone(s_start))
+            *start = 0;
+        else {
+            if(!py_checkint(s_start)) return false;
+            *start = py_toint(s_start);
+            if(*start < 0) *start += length;
+            _clip_int(start, 0, length);
+        }
+        if(py_isnone(s_stop))
+            *stop = length;
+        else {
+            if(!py_checkint(s_stop)) return false;
+            *stop = py_toint(s_stop);
+            if(*stop < 0) *stop += length;
+            _clip_int(stop, 0, length);
+        }
+    } else {
+        if(py_isnone(s_start))
+            *start = length - 1;
+        else {
+            if(!py_checkint(s_start)) return false;
+            *start = py_toint(s_start);
+            if(*start < 0) *start += length;
+            _clip_int(start, -1, length - 1);
+        }
+        if(py_isnone(s_stop))
+            *stop = -1;
+        else {
+            if(!py_checkint(s_stop)) return false;
+            *stop = py_toint(s_stop);
+            if(*stop < 0) *stop += length;
+            _clip_int(stop, -1, length - 1);
+        }
+    }
+    return true;
+}
+
+bool pk__normalize_index(int *index, int length){
+    if(*index < 0) *index += length;
+    if(*index < 0 || *index >= length){
+        return IndexError("index out of range");
+    }
+    return true;
+}
+
 py_Type pk_VM__new_type(pk_VM* self,
                         const char* name,
                         py_Type base,
diff --git a/src/public/py_list.c b/src/public/py_list.c
index fab80d4a..1c97f467 100644
--- a/src/public/py_list.c
+++ b/src/public/py_list.c
@@ -6,7 +6,6 @@
 
 typedef c11_vector List;
 
-
 void py_newlist(py_Ref out) {
     pk_VM* vm = pk_current_vm;
     PyObject* obj = pk_ManagedHeap__gcnew(&vm->heap, tp_list, 0, sizeof(List));
@@ -60,13 +59,48 @@ void py_list__insert(py_Ref self, int i, const py_Ref val) {
 }
 
 ////////////////////////////////
-static bool _py_list__len__(int argc, py_Ref argv){
+static bool _py_list__len__(int argc, py_Ref argv) {
     PY_CHECK_ARGC(1);
     py_i64 res = py_list__len(py_arg(0));
     py_newint(py_retval(), res);
     return true;
 }
 
+static bool _py_list__eq__(int argc, py_Ref argv) {
+    PY_CHECK_ARGC(2);
+    py_Ref _0 = py_arg(0);
+    py_Ref _1 = py_arg(1);
+    if(py_istype(_1, tp_list)) {
+        int length = py_list__len(_0);
+        if(length != py_list__len(_1)) {
+            py_newbool(py_retval(), false);
+            return true;
+        }
+        for(int i = 0; i < length; i++) {
+            py_Ref a = py_list__getitem(_0, i);
+            py_Ref b = py_list__getitem(_1, i);
+            int res = py_eq(a, b);
+            if(res == -1) return false;
+            if(res == 0) {
+                py_newbool(py_retval(), false);
+                return true;
+            }
+        }
+        py_newbool(py_retval(), true);
+    } else {
+        py_newnotimplemented(py_retval());
+    }
+    return true;
+}
+
+static bool _py_list__ne__(int argc, py_Ref argv) {
+    bool ok = _py_list__eq__(argc, argv);
+    if(!ok) return false;
+    py_Ref retval = py_retval();
+    py_newbool(retval, !py_tobool(retval));
+    return true;
+}
+
 py_Type pk_list__register() {
     pk_VM* vm = pk_current_vm;
     py_Type type = pk_VM__new_type(vm, "list", tp_object, NULL, false);
@@ -74,5 +108,7 @@ py_Type pk_list__register() {
     ti->dtor = (void (*)(void*))c11_vector__dtor;
 
     py_bindmagic(type, __len__, _py_list__len__);
+    py_bindmagic(type, __eq__, _py_list__eq__);
+    py_bindmagic(type, __ne__, _py_list__ne__);
     return type;
 }
\ No newline at end of file
diff --git a/src/public/py_str.c b/src/public/py_str.c
index a5b514cb..5d4cb87e 100644
--- a/src/public/py_str.c
+++ b/src/public/py_str.c
@@ -165,9 +165,23 @@ static bool _py_str__iter__(int argc, py_Ref argv) {
 static bool _py_str__getitem__(int argc, py_Ref argv) {
     PY_CHECK_ARGC(2);
     c11_string* self = py_touserdata(&argv[0]);
-    PY_CHECK_ARG_TYPE(1, tp_int);
-    c11_sv res = c11_string__u8_getitem(self, py_toint(py_arg(1)));
-    py_newstrn(py_retval(), res.data, res.size);
+    py_Ref _1 = py_arg(1);
+    if(_1->type == tp_int) {
+        int index = py_toint(py_arg(1));
+        pk__normalize_index(&index, self->size);
+        c11_sv res = c11_string__u8_getitem(self, index);
+        py_newstrn(py_retval(), res.data, res.size);
+    } else if(_1->type == tp_slice) {
+        int start, stop, step;
+        bool ok = pk__parse_int_slice(_1, c11_string__u8_length(self), &start, &stop, &step);
+        if(!ok) return false;
+        c11_string* res = c11_string__u8_slice(self, start, stop, step);
+        py_newstrn(py_retval(), res->data, res->size);
+        c11_string__delete(res);
+        return true;
+    } else {
+        return TypeError("str indices must be integers");
+    }
     return true;
 }
 
@@ -257,6 +271,77 @@ static bool _py_str__join(int argc, py_Ref argv) {
     return false;
 }
 
+static bool _py_str__replace(int argc, py_Ref argv) {
+    PY_CHECK_ARGC(3);
+    c11_string* self = py_touserdata(&argv[0]);
+    PY_CHECK_ARG_TYPE(1, tp_str);
+    PY_CHECK_ARG_TYPE(2, tp_str);
+    c11_string* old = py_touserdata(&argv[1]);
+    c11_string* new_ = py_touserdata(&argv[2]);
+    c11_string* res =
+        c11_sv__replace2(c11_string__sv(self), c11_string__sv(old), c11_string__sv(new_));
+    py_newstrn(py_retval(), res->data, res->size);
+    c11_string__delete(res);
+    return true;
+}
+
+static bool _py_str__split(int argc, py_Ref argv) {
+    c11_sv self = c11_string__sv(py_touserdata(&argv[0]));
+    c11_vector res;
+    if(argc > 2) return TypeError("split() takes at most 2 arguments");
+    if(argc == 1) {
+        // sep = ' '
+        res = c11_sv__split(self, ' ');
+    }
+    if(argc == 2) {
+        // sep = argv[1]
+        if(!py_checkstr(&argv[1])) return false;
+        c11_sv sep = c11_string__sv(py_touserdata(&argv[1]));
+        res = c11_sv__split2(self, sep);
+    }
+    py_newlistn(py_retval(), res.count);
+    for(int i = 0; i < res.count; i++) {
+        c11_sv item = c11__getitem(c11_sv, &res, i);
+        py_newstrn(py_list__getitem(py_retval(), i), item.data, item.size);
+    }
+    c11_vector__dtor(&res);
+    return true;
+}
+
+static bool _py_str__count(int argc, py_Ref argv) {
+    PY_CHECK_ARGC(2);
+    c11_string* self = py_touserdata(&argv[0]);
+    PY_CHECK_ARG_TYPE(1, tp_str);
+    c11_string* sub = py_touserdata(&argv[1]);
+    int res = c11_sv__count(c11_string__sv(self), c11_string__sv(sub));
+    py_newint(py_retval(), res);
+    return true;
+}
+
+static bool _py_str__strip(int argc, py_Ref argv) {
+    PY_CHECK_ARGC(1);
+    c11_string* self = py_touserdata(&argv[0]);
+    c11_sv res = c11_sv__strip(c11_string__sv(self), true, true);
+    py_newstrn(py_retval(), res.data, res.size);
+    return true;
+}
+
+static bool _py_str__lstrip(int argc, py_Ref argv) {
+    PY_CHECK_ARGC(1);
+    c11_string* self = py_touserdata(&argv[0]);
+    c11_sv res = c11_sv__strip(c11_string__sv(self), true, false);
+    py_newstrn(py_retval(), res.data, res.size);
+    return true;
+}
+
+static bool _py_str__rstrip(int argc, py_Ref argv) {
+    PY_CHECK_ARGC(1);
+    c11_string* self = py_touserdata(&argv[0]);
+    c11_sv res = c11_sv__strip(c11_string__sv(self), false, true);
+    py_newstrn(py_retval(), res.data, res.size);
+    return true;
+}
+
 py_Type pk_str__register() {
     pk_VM* vm = pk_current_vm;
     py_Type type = pk_VM__new_type(vm, "str", tp_object, NULL, false);
@@ -286,6 +371,12 @@ py_Type pk_str__register() {
     py_bindmethod(tp_str, "startswith", _py_str__startswith);
     py_bindmethod(tp_str, "endswith", _py_str__endswith);
     py_bindmethod(tp_str, "join", _py_str__join);
+    py_bindmethod(tp_str, "replace", _py_str__replace);
+    py_bindmethod(tp_str, "split", _py_str__split);
+    py_bindmethod(tp_str, "count", _py_str__count);
+    py_bindmethod(tp_str, "strip", _py_str__strip);
+    py_bindmethod(tp_str, "lstrip", _py_str__lstrip);
+    py_bindmethod(tp_str, "rstrip", _py_str__rstrip);
     return type;
 }