diff --git a/pkg/compiler/native_test.go b/pkg/compiler/native_test.go
index 4f7ae97e2..03c3fc77b 100644
--- a/pkg/compiler/native_test.go
+++ b/pkg/compiler/native_test.go
@@ -225,7 +225,15 @@ func TestNativeHelpersCompile(t *testing.T) {
 		{"base58Encode", []string{"[]byte{1, 2, 3}"}},
 		{"base58Decode", []string{"[]byte{1, 2, 3}"}},
 		{"itoa", []string{"4", "10"}},
+		{"itoa10", []string{"4"}},
 		{"atoi", []string{`"4"`, "10"}},
+		{"atoi10", []string{`"4"`}},
+		{"memoryCompare", []string{"[]byte{1}", "[]byte{2}"}},
+		{"memorySearch", []string{"[]byte{1}", "[]byte{2}"}},
+		{"memorySearchIndex", []string{"[]byte{1}", "[]byte{2}", "3"}},
+		{"memorySearchLastIndex", []string{"[]byte{1}", "[]byte{2}", "3"}},
+		{"stringSplit", []string{`"a,b"`, `","`}},
+		{"stringSplitNonEmpty", []string{`"a,b"`, `","`}},
 	})
 }
 
@@ -239,10 +247,33 @@ func runNativeTestCases(t *testing.T, ctr interop.ContractMD, name string, testC
 	})
 }
 
-func runNativeTestCase(t *testing.T, ctr interop.ContractMD, name, method string, params ...string) {
-	md, ok := ctr.GetMethod(strings.TrimSuffix(method, "WithData"), len(params))
-	require.True(t, ok)
+func getMethod(t *testing.T, ctr interop.ContractMD, name string, params []string) interop.MethodAndPrice {
+	paramLen := len(params)
 
+	switch {
+	case name == "itoa10" || name == "atoi10":
+		name = name[:4]
+	case strings.HasPrefix(name, "memorySearch"):
+		if strings.HasSuffix(name, "LastIndex") {
+			paramLen += 1 // true should be appended inside of an interop
+		}
+		name = "memorySearch"
+	case strings.HasPrefix(name, "stringSplit"):
+		if strings.HasSuffix(name, "NonEmpty") {
+			paramLen += 1 // true should be appended inside of an interop
+		}
+		name = "stringSplit"
+	default:
+		name = strings.TrimSuffix(name, "WithData")
+	}
+
+	md, ok := ctr.GetMethod(name, paramLen)
+	require.True(t, ok)
+	return md
+}
+
+func runNativeTestCase(t *testing.T, ctr interop.ContractMD, name, method string, params ...string) {
+	md := getMethod(t, ctr, method, params)
 	isVoid := md.MD.ReturnType == smartcontract.VoidType
 	srcTmpl := `package foo
 		import "github.com/nspcc-dev/neo-go/pkg/interop/native/%s"
diff --git a/pkg/core/native/std.go b/pkg/core/native/std.go
index ed559000f..243624753 100644
--- a/pkg/core/native/std.go
+++ b/pkg/core/native/std.go
@@ -1,6 +1,7 @@
 package native
 
 import (
+	"bytes"
 	"encoding/base64"
 	"encoding/hex"
 	"errors"
@@ -22,13 +23,20 @@ type Std struct {
 	interop.ContractMD
 }
 
-const stdContractID = -2
+const (
+	stdContractID = -2
+
+	// stdMaxInputLength is the maximum input length for string-related methods.
+	stdMaxInputLength = 1024
+)
 
 var (
 	// ErrInvalidBase is returned when base is invalid.
 	ErrInvalidBase = errors.New("invalid base")
 	// ErrInvalidFormat is returned when string is not a number.
 	ErrInvalidFormat = errors.New("invalid format")
+	// ErrTooBigInput is returned when input exceeds size limit.
+	ErrTooBigInput = errors.New("input is too big")
 )
 
 func newStd() *Std {
@@ -61,30 +69,80 @@ func newStd() *Std {
 	md = newMethodAndPrice(s.itoa, 1<<12, callflag.NoneFlag)
 	s.AddMethod(md, desc)
 
+	desc = newDescriptor("itoa", smartcontract.StringType,
+		manifest.NewParameter("value", smartcontract.IntegerType))
+	md = newMethodAndPrice(s.itoa10, 1<<12, callflag.NoneFlag)
+	s.AddMethod(md, desc)
+
 	desc = newDescriptor("atoi", smartcontract.IntegerType,
 		manifest.NewParameter("value", smartcontract.StringType),
 		manifest.NewParameter("base", smartcontract.IntegerType))
-	md = newMethodAndPrice(s.atoi, 1<<12, callflag.NoneFlag)
+	md = newMethodAndPrice(s.atoi, 1<<6, callflag.NoneFlag)
+	s.AddMethod(md, desc)
+
+	desc = newDescriptor("atoi", smartcontract.IntegerType,
+		manifest.NewParameter("value", smartcontract.StringType))
+	md = newMethodAndPrice(s.atoi10, 1<<6, callflag.NoneFlag)
 	s.AddMethod(md, desc)
 
 	desc = newDescriptor("base64Encode", smartcontract.StringType,
 		manifest.NewParameter("data", smartcontract.ByteArrayType))
-	md = newMethodAndPrice(s.base64Encode, 1<<12, callflag.NoneFlag)
+	md = newMethodAndPrice(s.base64Encode, 1<<5, callflag.NoneFlag)
 	s.AddMethod(md, desc)
 
 	desc = newDescriptor("base64Decode", smartcontract.ByteArrayType,
 		manifest.NewParameter("s", smartcontract.StringType))
-	md = newMethodAndPrice(s.base64Decode, 1<<12, callflag.NoneFlag)
+	md = newMethodAndPrice(s.base64Decode, 1<<5, callflag.NoneFlag)
 	s.AddMethod(md, desc)
 
 	desc = newDescriptor("base58Encode", smartcontract.StringType,
 		manifest.NewParameter("data", smartcontract.ByteArrayType))
-	md = newMethodAndPrice(s.base58Encode, 1<<12, callflag.NoneFlag)
+	md = newMethodAndPrice(s.base58Encode, 1<<13, callflag.NoneFlag)
 	s.AddMethod(md, desc)
 
 	desc = newDescriptor("base58Decode", smartcontract.ByteArrayType,
 		manifest.NewParameter("s", smartcontract.StringType))
-	md = newMethodAndPrice(s.base58Decode, 1<<12, callflag.NoneFlag)
+	md = newMethodAndPrice(s.base58Decode, 1<<10, callflag.NoneFlag)
+	s.AddMethod(md, desc)
+
+	desc = newDescriptor("memoryCompare", smartcontract.IntegerType,
+		manifest.NewParameter("str1", smartcontract.ByteArrayType),
+		manifest.NewParameter("str2", smartcontract.ByteArrayType))
+	md = newMethodAndPrice(s.memoryCompare, 1<<5, callflag.NoneFlag)
+	s.AddMethod(md, desc)
+
+	desc = newDescriptor("memorySearch", smartcontract.IntegerType,
+		manifest.NewParameter("mem", smartcontract.ByteArrayType),
+		manifest.NewParameter("value", smartcontract.ByteArrayType))
+	md = newMethodAndPrice(s.memorySearch2, 1<<6, callflag.NoneFlag)
+	s.AddMethod(md, desc)
+
+	desc = newDescriptor("memorySearch", smartcontract.IntegerType,
+		manifest.NewParameter("mem", smartcontract.ByteArrayType),
+		manifest.NewParameter("value", smartcontract.ByteArrayType),
+		manifest.NewParameter("start", smartcontract.IntegerType))
+	md = newMethodAndPrice(s.memorySearch3, 1<<6, callflag.NoneFlag)
+	s.AddMethod(md, desc)
+
+	desc = newDescriptor("memorySearch", smartcontract.IntegerType,
+		manifest.NewParameter("mem", smartcontract.ByteArrayType),
+		manifest.NewParameter("value", smartcontract.ByteArrayType),
+		manifest.NewParameter("start", smartcontract.IntegerType),
+		manifest.NewParameter("backward", smartcontract.BoolType))
+	md = newMethodAndPrice(s.memorySearch4, 1<<6, callflag.NoneFlag)
+	s.AddMethod(md, desc)
+
+	desc = newDescriptor("stringSplit", smartcontract.ArrayType,
+		manifest.NewParameter("str", smartcontract.StringType),
+		manifest.NewParameter("separator", smartcontract.StringType))
+	md = newMethodAndPrice(s.stringSplit2, 1<<8, callflag.NoneFlag)
+	s.AddMethod(md, desc)
+
+	desc = newDescriptor("stringSplit", smartcontract.ArrayType,
+		manifest.NewParameter("str", smartcontract.StringType),
+		manifest.NewParameter("separator", smartcontract.StringType),
+		manifest.NewParameter("removeEmptyEntries", smartcontract.BoolType))
+	md = newMethodAndPrice(s.stringSplit3, 1<<8, callflag.NoneFlag)
 	s.AddMethod(md, desc)
 
 	return s
@@ -142,6 +200,11 @@ func (s *Std) jsonDeserialize(_ *interop.Context, args []stackitem.Item) stackit
 	return item
 }
 
+func (s *Std) itoa10(_ *interop.Context, args []stackitem.Item) stackitem.Item {
+	num := toBigInt(args[0])
+	return stackitem.NewByteArray([]byte(num.Text(10)))
+}
+
 func (s *Std) itoa(_ *interop.Context, args []stackitem.Item) stackitem.Item {
 	num := toBigInt(args[0])
 	base := toBigInt(args[1])
@@ -170,8 +233,22 @@ func (s *Std) itoa(_ *interop.Context, args []stackitem.Item) stackitem.Item {
 	return stackitem.NewByteArray([]byte(str))
 }
 
+func (s *Std) atoi10(_ *interop.Context, args []stackitem.Item) stackitem.Item {
+	num := s.toLimitedString(args[0])
+	res := s.atoi10Aux(num)
+	return stackitem.NewBigInteger(res)
+}
+
+func (s *Std) atoi10Aux(num string) *big.Int {
+	bi, ok := new(big.Int).SetString(num, 10)
+	if !ok {
+		panic(ErrInvalidFormat)
+	}
+	return bi
+}
+
 func (s *Std) atoi(_ *interop.Context, args []stackitem.Item) stackitem.Item {
-	num := toString(args[0])
+	num := s.toLimitedString(args[0])
 	base := toBigInt(args[1])
 	if !base.IsInt64() {
 		panic(ErrInvalidBase)
@@ -179,11 +256,7 @@ func (s *Std) atoi(_ *interop.Context, args []stackitem.Item) stackitem.Item {
 	var bi *big.Int
 	switch b := base.Int64(); b {
 	case 10:
-		var ok bool
-		bi, ok = new(big.Int).SetString(num, int(b))
-		if !ok {
-			panic(ErrInvalidFormat)
-		}
+		bi = s.atoi10Aux(num)
 	case 16:
 		changed := len(num)%2 != 0
 		if changed {
@@ -213,17 +286,14 @@ func reverse(b []byte) {
 }
 
 func (s *Std) base64Encode(_ *interop.Context, args []stackitem.Item) stackitem.Item {
-	src, err := args[0].TryBytes()
-	if err != nil {
-		panic(err)
-	}
+	src := s.toLimitedBytes(args[0])
 	result := base64.StdEncoding.EncodeToString(src)
 
 	return stackitem.NewByteArray([]byte(result))
 }
 
 func (s *Std) base64Decode(_ *interop.Context, args []stackitem.Item) stackitem.Item {
-	src := toString(args[0])
+	src := s.toLimitedString(args[0])
 	result, err := base64.StdEncoding.DecodeString(src)
 	if err != nil {
 		panic(err)
@@ -233,17 +303,14 @@ func (s *Std) base64Decode(_ *interop.Context, args []stackitem.Item) stackitem.
 }
 
 func (s *Std) base58Encode(_ *interop.Context, args []stackitem.Item) stackitem.Item {
-	src, err := args[0].TryBytes()
-	if err != nil {
-		panic(err)
-	}
+	src := s.toLimitedBytes(args[0])
 	result := base58.Encode(src)
 
 	return stackitem.NewByteArray([]byte(result))
 }
 
 func (s *Std) base58Decode(_ *interop.Context, args []stackitem.Item) stackitem.Item {
-	src := toString(args[0])
+	src := s.toLimitedString(args[0])
 	result, err := base58.Decode(src)
 	if err != nil {
 		panic(err)
@@ -252,6 +319,85 @@ func (s *Std) base58Decode(_ *interop.Context, args []stackitem.Item) stackitem.
 	return stackitem.NewByteArray(result)
 }
 
+func (s *Std) memoryCompare(_ *interop.Context, args []stackitem.Item) stackitem.Item {
+	s1 := s.toLimitedBytes(args[0])
+	s2 := s.toLimitedBytes(args[1])
+	return stackitem.NewBigInteger(big.NewInt(int64(bytes.Compare(s1, s2))))
+}
+
+func (s *Std) memorySearch2(_ *interop.Context, args []stackitem.Item) stackitem.Item {
+	mem := s.toLimitedBytes(args[0])
+	val := s.toLimitedBytes(args[1])
+	index := s.memorySearchAux(mem, val, 0, false)
+	return stackitem.NewBigInteger(big.NewInt(int64(index)))
+}
+
+func (s *Std) memorySearch3(_ *interop.Context, args []stackitem.Item) stackitem.Item {
+	mem := s.toLimitedBytes(args[0])
+	val := s.toLimitedBytes(args[1])
+	start := toUint32(args[2])
+	index := s.memorySearchAux(mem, val, int(start), false)
+	return stackitem.NewBigInteger(big.NewInt(int64(index)))
+}
+
+func (s *Std) memorySearch4(_ *interop.Context, args []stackitem.Item) stackitem.Item {
+	mem := s.toLimitedBytes(args[0])
+	val := s.toLimitedBytes(args[1])
+	start := toUint32(args[2])
+	backward, err := args[3].TryBool()
+	if err != nil {
+		panic(err)
+	}
+
+	index := s.memorySearchAux(mem, val, int(start), backward)
+	return stackitem.NewBigInteger(big.NewInt(int64(index)))
+}
+
+func (s *Std) memorySearchAux(mem, val []byte, start int, backward bool) int {
+	if backward {
+		if start > len(mem) { // panic in case if cap(mem) > len(mem) for some reasons
+			panic("invalid start index")
+		}
+		return bytes.LastIndex(mem[:start], val)
+	}
+
+	index := bytes.Index(mem[start:], val)
+	if index < 0 {
+		return -1
+	}
+	return index + start
+}
+
+func (s *Std) stringSplit2(_ *interop.Context, args []stackitem.Item) stackitem.Item {
+	str := s.toLimitedString(args[0])
+	sep := toString(args[1])
+	return stackitem.NewArray(s.stringSplitAux(str, sep, false))
+}
+
+func (s *Std) stringSplit3(_ *interop.Context, args []stackitem.Item) stackitem.Item {
+	str := s.toLimitedString(args[0])
+	sep := toString(args[1])
+	removeEmpty, err := args[2].TryBool()
+	if err != nil {
+		panic(err)
+	}
+
+	return stackitem.NewArray(s.stringSplitAux(str, sep, removeEmpty))
+}
+
+func (s *Std) stringSplitAux(str, sep string, removeEmpty bool) []stackitem.Item {
+	var result []stackitem.Item
+
+	arr := strings.Split(str, sep)
+	for i := range arr {
+		if !removeEmpty || len(arr[i]) != 0 {
+			result = append(result, stackitem.Make(arr[i]))
+		}
+	}
+
+	return result
+}
+
 // Metadata implements Contract interface.
 func (s *Std) Metadata() *interop.ContractMD {
 	return &s.ContractMD
@@ -271,3 +417,22 @@ func (s *Std) OnPersist(ic *interop.Context) error {
 func (s *Std) PostPersist(ic *interop.Context) error {
 	return nil
 }
+
+func (s *Std) toLimitedBytes(item stackitem.Item) []byte {
+	src, err := item.TryBytes()
+	if err != nil {
+		panic(err)
+	}
+	if len(src) > stdMaxInputLength {
+		panic(ErrTooBigInput)
+	}
+	return src
+}
+
+func (s *Std) toLimitedString(item stackitem.Item) string {
+	src := toString(item)
+	if len(src) > stdMaxInputLength {
+		panic(ErrTooBigInput)
+	}
+	return src
+}
diff --git a/pkg/core/native/std_test.go b/pkg/core/native/std_test.go
index f5a3bf15c..68021c665 100644
--- a/pkg/core/native/std_test.go
+++ b/pkg/core/native/std_test.go
@@ -5,6 +5,7 @@ import (
 	"encoding/hex"
 	"math"
 	"math/big"
+	"strings"
 	"testing"
 
 	"github.com/mr-tron/base58"
@@ -49,6 +50,18 @@ func TestStdLibItoaAtoi(t *testing.T) {
 				actual = s.atoi(ic, []stackitem.Item{stackitem.Make(tc.result), stackitem.Make(tc.base)})
 			})
 			require.Equal(t, stackitem.Make(tc.num), actual)
+
+			if tc.base.Int64() == 10 {
+				require.NotPanics(t, func() {
+					actual = s.itoa10(ic, []stackitem.Item{stackitem.Make(tc.num)})
+				})
+				require.Equal(t, stackitem.Make(tc.result), actual)
+
+				require.NotPanics(t, func() {
+					actual = s.atoi10(ic, []stackitem.Item{stackitem.Make(tc.result)})
+				})
+				require.Equal(t, stackitem.Make(tc.num), actual)
+			}
 		}
 
 		t.Run("-1", func(t *testing.T) {
@@ -90,6 +103,7 @@ func TestStdLibItoaAtoi(t *testing.T) {
 			{"1_000", big.NewInt(10), ErrInvalidFormat},
 			{"FE", big.NewInt(10), ErrInvalidFormat},
 			{"XD", big.NewInt(16), ErrInvalidFormat},
+			{strings.Repeat("0", stdMaxInputLength+1), big.NewInt(10), ErrTooBigInput},
 		}
 
 		for _, tc := range testCases {
@@ -152,18 +166,28 @@ func TestStdLibEncodeDecode(t *testing.T) {
 	ic := &interop.Context{VM: vm.New()}
 	var actual stackitem.Item
 
+	bigInputArgs := []stackitem.Item{stackitem.Make(strings.Repeat("6", stdMaxInputLength+1))}
+
 	t.Run("Encode64", func(t *testing.T) {
 		require.NotPanics(t, func() {
 			actual = s.base64Encode(ic, []stackitem.Item{stackitem.Make(original)})
 		})
 		require.Equal(t, stackitem.Make(encoded64), actual)
 	})
+	t.Run("Encode64/error", func(t *testing.T) {
+		require.PanicsWithError(t, ErrTooBigInput.Error(),
+			func() { s.base64Encode(ic, bigInputArgs) })
+	})
 	t.Run("Encode58", func(t *testing.T) {
 		require.NotPanics(t, func() {
 			actual = s.base58Encode(ic, []stackitem.Item{stackitem.Make(original)})
 		})
 		require.Equal(t, stackitem.Make(encoded58), actual)
 	})
+	t.Run("Encode58/error", func(t *testing.T) {
+		require.PanicsWithError(t, ErrTooBigInput.Error(),
+			func() { s.base58Encode(ic, bigInputArgs) })
+	})
 	t.Run("Decode64/positive", func(t *testing.T) {
 		require.NotPanics(t, func() {
 			actual = s.base64Decode(ic, []stackitem.Item{stackitem.Make(encoded64)})
@@ -177,6 +201,8 @@ func TestStdLibEncodeDecode(t *testing.T) {
 		require.Panics(t, func() {
 			_ = s.base64Decode(ic, []stackitem.Item{stackitem.NewInterop(nil)})
 		})
+		require.PanicsWithError(t, ErrTooBigInput.Error(),
+			func() { s.base64Decode(ic, bigInputArgs) })
 	})
 	t.Run("Decode58/positive", func(t *testing.T) {
 		require.NotPanics(t, func() {
@@ -191,6 +217,8 @@ func TestStdLibEncodeDecode(t *testing.T) {
 		require.Panics(t, func() {
 			_ = s.base58Decode(ic, []stackitem.Item{stackitem.NewInterop(nil)})
 		})
+		require.PanicsWithError(t, ErrTooBigInput.Error(),
+			func() { s.base58Decode(ic, bigInputArgs) })
 	})
 }
 
@@ -326,3 +354,174 @@ func TestStdLibSerializeDeserialize(t *testing.T) {
 		})
 	})
 }
+
+func TestMemoryCompare(t *testing.T) {
+	s := newStd()
+	ic := &interop.Context{VM: vm.New()}
+
+	check := func(t *testing.T, result int64, s1, s2 string) {
+		actual := s.memoryCompare(ic, []stackitem.Item{stackitem.Make(s1), stackitem.Make(s2)})
+		require.Equal(t, big.NewInt(result), actual.Value())
+	}
+
+	check(t, -1, "a", "ab")
+	check(t, 1, "ab", "a")
+	check(t, 0, "ab", "ab")
+	check(t, -1, "", "a")
+	check(t, 0, "", "")
+
+	t.Run("C# compatibility", func(t *testing.T) {
+		// These tests are taken from C# node.
+		check(t, -1, "abc", "c")
+		check(t, -1, "abc", "d")
+		check(t, 0, "abc", "abc")
+		check(t, -1, "abc", "abcd")
+	})
+
+	t.Run("big arguments", func(t *testing.T) {
+		s1 := stackitem.Make(strings.Repeat("x", stdMaxInputLength+1))
+		s2 := stackitem.Make("xxx")
+
+		require.PanicsWithError(t, ErrTooBigInput.Error(),
+			func() { s.memoryCompare(ic, []stackitem.Item{s1, s2}) })
+
+		require.PanicsWithError(t, ErrTooBigInput.Error(),
+			func() { s.memoryCompare(ic, []stackitem.Item{s2, s1}) })
+	})
+}
+
+func TestMemorySearch(t *testing.T) {
+	s := newStd()
+	ic := &interop.Context{VM: vm.New()}
+
+	check := func(t *testing.T, result int64, args ...interface{}) {
+		items := make([]stackitem.Item, len(args))
+		for i := range args {
+			items[i] = stackitem.Make(args[i])
+		}
+
+		var actual stackitem.Item
+		switch len(items) {
+		case 2:
+			actual = s.memorySearch2(ic, items)
+		case 3:
+			actual = s.memorySearch3(ic, items)
+		case 4:
+			actual = s.memorySearch4(ic, items)
+		default:
+			panic("invalid args length")
+		}
+		require.Equal(t, big.NewInt(result), actual.Value())
+	}
+
+	t.Run("C# compatibility", func(t *testing.T) {
+		// These tests are taken from C# node.
+		check(t, 2, "abc", "c", 0)
+		check(t, 2, "abc", "c", 1)
+		check(t, 2, "abc", "c", 2)
+		check(t, -1, "abc", "c", 3)
+		check(t, -1, "abc", "d", 0)
+
+		check(t, 2, "abc", "c", 0, false)
+		check(t, 2, "abc", "c", 1, false)
+		check(t, 2, "abc", "c", 2, false)
+		check(t, -1, "abc", "c", 3, false)
+		check(t, -1, "abc", "d", 0, false)
+
+		check(t, -1, "abc", "c", 0, true)
+		check(t, -1, "abc", "c", 1, true)
+		check(t, -1, "abc", "c", 2, true)
+		check(t, 2, "abc", "c", 3, true)
+		check(t, -1, "abc", "d", 0, true)
+	})
+
+	t.Run("boundary indices", func(t *testing.T) {
+		arg := stackitem.Make("aaa")
+		require.Panics(t, func() {
+			s.memorySearch3(ic, []stackitem.Item{arg, arg, stackitem.Make(-1)})
+		})
+		require.Panics(t, func() {
+			s.memorySearch3(ic, []stackitem.Item{arg, arg, stackitem.Make(4)})
+		})
+		t.Run("still in capacity", func(t *testing.T) {
+			require.Panics(t, func() {
+				arr := stackitem.NewByteArray(make([]byte, 5, 10))
+				s.memorySearch3(ic, []stackitem.Item{arr, arg, stackitem.Make(7)})
+			})
+			require.Panics(t, func() {
+				arr := stackitem.NewByteArray(make([]byte, 5, 10))
+				s.memorySearch4(ic, []stackitem.Item{arr, arg,
+					stackitem.Make(7), stackitem.Make(true)})
+			})
+		})
+	})
+
+	t.Run("big arguments", func(t *testing.T) {
+		s1 := stackitem.Make(strings.Repeat("x", stdMaxInputLength+1))
+		s2 := stackitem.Make("xxx")
+		start := stackitem.Make(1)
+		b := stackitem.Make(true)
+
+		require.PanicsWithError(t, ErrTooBigInput.Error(),
+			func() { s.memorySearch2(ic, []stackitem.Item{s1, s2}) })
+
+		require.PanicsWithError(t, ErrTooBigInput.Error(),
+			func() { s.memorySearch2(ic, []stackitem.Item{s2, s1}) })
+
+		require.PanicsWithError(t, ErrTooBigInput.Error(),
+			func() { s.memorySearch3(ic, []stackitem.Item{s1, s2, start}) })
+
+		require.PanicsWithError(t, ErrTooBigInput.Error(),
+			func() { s.memorySearch3(ic, []stackitem.Item{s2, s1, start}) })
+
+		require.PanicsWithError(t, ErrTooBigInput.Error(),
+			func() { s.memorySearch4(ic, []stackitem.Item{s1, s2, start, b}) })
+
+		require.PanicsWithError(t, ErrTooBigInput.Error(),
+			func() { s.memorySearch4(ic, []stackitem.Item{s2, s1, start, b}) })
+	})
+}
+
+func TestStringSplit(t *testing.T) {
+	s := newStd()
+	ic := &interop.Context{VM: vm.New()}
+
+	check := func(t *testing.T, result []string, str, sep string, remove interface{}) {
+		args := []stackitem.Item{stackitem.Make(str), stackitem.Make(sep)}
+		var actual stackitem.Item
+		if remove == nil {
+			actual = s.stringSplit2(ic, args)
+		} else {
+			args = append(args, stackitem.NewBool(remove.(bool)))
+			actual = s.stringSplit3(ic, args)
+		}
+
+		arr, ok := actual.Value().([]stackitem.Item)
+		require.True(t, ok)
+		require.Equal(t, len(result), len(arr))
+		for i := range result {
+			require.Equal(t, stackitem.Make(result[i]), arr[i])
+		}
+	}
+
+	check(t, []string{"a", "b", "c"}, "abc", "", nil)
+	check(t, []string{"a", "b", "c"}, "abc", "", true)
+	check(t, []string{"a", "c", "", "", "d"}, "abcbbbd", "b", nil)
+	check(t, []string{"a", "c", "", "", "d"}, "abcbbbd", "b", false)
+	check(t, []string{"a", "c", "d"}, "abcbbbd", "b", true)
+	check(t, []string{""}, "", "abc", nil)
+	check(t, []string{}, "", "abc", true)
+
+	t.Run("C# compatibility", func(t *testing.T) {
+		// These tests are taken from C# node.
+		check(t, []string{"a", "b"}, "a,b", ",", nil)
+	})
+
+	t.Run("big arguments", func(t *testing.T) {
+		s1 := stackitem.Make(strings.Repeat("x", stdMaxInputLength+1))
+		s2 := stackitem.Make("xxx")
+
+		require.PanicsWithError(t, ErrTooBigInput.Error(),
+			func() { s.stringSplit2(ic, []stackitem.Item{s1, s2}) })
+	})
+}
diff --git a/pkg/interop/native/std/std.go b/pkg/interop/native/std/std.go
index fa5f4dadc..af263c8ba 100644
--- a/pkg/interop/native/std/std.go
+++ b/pkg/interop/native/std/std.go
@@ -93,9 +93,66 @@ func Itoa(num int, base int) string {
 		num, base).(string)
 }
 
+// Itoa10 converts num in a base 10 to string.
+// It uses `itoa` method of StdLib native contract.
+func Itoa10(num int) string {
+	return contract.Call(interop.Hash160(Hash), "itoa", contract.NoneFlag,
+		num).(string)
+}
+
 // Atoi converts string to a number in a given base. Base should be either 10 or 16.
 // It uses `atoi` method of StdLib native contract.
 func Atoi(s string, base int) int {
 	return contract.Call(interop.Hash160(Hash), "atoi", contract.NoneFlag,
 		s, base).(int)
 }
+
+// Atoi10 converts string to a number in a base 10.
+// It uses `atoi` method of StdLib native contract.
+func Atoi10(s string) int {
+	return contract.Call(interop.Hash160(Hash), "atoi", contract.NoneFlag,
+		s).(int)
+}
+
+// MemoryCompare is similar to bytes.Compare:
+// The result will be 0 if a==b, -1 if a < b, and +1 if a > b.
+// It uses `memoryCompare` method of StdLib native contract.
+func MemoryCompare(s1, s2 []byte) int {
+	return contract.Call(interop.Hash160(Hash), "memoryCompare", contract.NoneFlag,
+		s1, s2).(int)
+}
+
+// MemorySearch returns index of the first occurrence of val in mem.
+// If not found, -1 is returned. It uses `memorySearch` method of StdLib native contract.
+func MemorySearch(mem, pattern []byte) int {
+	return contract.Call(interop.Hash160(Hash), "memorySearch", contract.NoneFlag,
+		mem, pattern).(int)
+}
+
+// MemorySearchIndex returns index of the first occurrence of val in mem starting from start.
+// If not found, -1 is returned. It uses `memorySearch` method of StdLib native contract.
+func MemorySearchIndex(mem, pattern []byte, start int) int {
+	return contract.Call(interop.Hash160(Hash), "memorySearch", contract.NoneFlag,
+		mem, pattern, start).(int)
+}
+
+// MemorySearchLastIndex returns index of the last occurrence of val in mem ending before start.
+// If not found, -1 is returned. It uses `memorySearch` method of StdLib native contract.
+func MemorySearchLastIndex(mem, pattern []byte, start int) int {
+	return contract.Call(interop.Hash160(Hash), "memorySearch", contract.NoneFlag,
+		mem, pattern, start, true).(int)
+}
+
+// StringSplit splits s by occurrences of sep.
+// It uses `stringSplit` method of StdLib native contract.
+func StringSplit(s, sep string) []string {
+	return contract.Call(interop.Hash160(Hash), "stringSplit", contract.NoneFlag,
+		s, sep).([]string)
+}
+
+// StringSplitNonEmpty splits s by occurrences of sep and returns a list of non-empty items.
+// It uses `stringSplit` method of StdLib native contract.
+func StringSplitNonEmpty(s, sep string) []string {
+	return contract.Call(interop.Hash160(Hash), "stringSplit", contract.NoneFlag,
+		s, sep, true).([]string)
+}