diff --git a/cmd/kube-scheduler/app/options/options_test.go b/cmd/kube-scheduler/app/options/options_test.go
index 1ee6ec34ac8..11c6f905984 100644
--- a/cmd/kube-scheduler/app/options/options_test.go
+++ b/cmd/kube-scheduler/app/options/options_test.go
@@ -1133,7 +1133,7 @@ profiles:
 				ConfigFile: unknownFieldConfig,
 				Logs:       logs.NewOptions(),
 			},
-			expectedError: "found unknown field: foo",
+			expectedError: `unknown field "foo"`,
 			checkErrFn:    runtime.IsStrictDecodingError,
 		},
 		{
diff --git a/pkg/api/testing/serialization_test.go b/pkg/api/testing/serialization_test.go
index f5c725998db..31cd68326ad 100644
--- a/pkg/api/testing/serialization_test.go
+++ b/pkg/api/testing/serialization_test.go
@@ -26,7 +26,6 @@ import (
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
-	jsoniter "github.com/json-iterator/go"
 
 	appsv1 "k8s.io/api/apps/v1"
 	v1 "k8s.io/api/core/v1"
@@ -38,7 +37,6 @@ import (
 	"k8s.io/apimachinery/pkg/conversion"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
-	"k8s.io/apimachinery/pkg/runtime/serializer/json"
 	"k8s.io/apimachinery/pkg/runtime/serializer/streaming"
 	"k8s.io/apimachinery/pkg/util/sets"
 	"k8s.io/apimachinery/pkg/watch"
@@ -589,59 +587,6 @@ func BenchmarkDecodeIntoJSON(b *testing.B) {
 	b.StopTimer()
 }
 
-// BenchmarkDecodeIntoJSONCodecGenConfigFast provides a baseline
-// for JSON decode performance with jsoniter.ConfigFast
-func BenchmarkDecodeIntoJSONCodecGenConfigFast(b *testing.B) {
-	kcodec := legacyscheme.Codecs.LegacyCodec(v1.SchemeGroupVersion)
-	items := benchmarkItems(b)
-	width := len(items)
-	encoded := make([][]byte, width)
-	for i := range items {
-		data, err := runtime.Encode(kcodec, &items[i])
-		if err != nil {
-			b.Fatal(err)
-		}
-		encoded[i] = data
-	}
-
-	b.ResetTimer()
-	for i := 0; i < b.N; i++ {
-		obj := v1.Pod{}
-		if err := jsoniter.ConfigFastest.Unmarshal(encoded[i%width], &obj); err != nil {
-			b.Fatal(err)
-		}
-	}
-	b.StopTimer()
-}
-
-// BenchmarkDecodeIntoJSONCodecGenConfigCompatibleWithStandardLibrary provides a
-// baseline for JSON decode performance with
-// jsoniter.ConfigCompatibleWithStandardLibrary, but with case sensitivity set
-// to true
-func BenchmarkDecodeIntoJSONCodecGenConfigCompatibleWithStandardLibrary(b *testing.B) {
-	kcodec := legacyscheme.Codecs.LegacyCodec(v1.SchemeGroupVersion)
-	items := benchmarkItems(b)
-	width := len(items)
-	encoded := make([][]byte, width)
-	for i := range items {
-		data, err := runtime.Encode(kcodec, &items[i])
-		if err != nil {
-			b.Fatal(err)
-		}
-		encoded[i] = data
-	}
-
-	b.ResetTimer()
-	iter := json.CaseSensitiveJSONIterator()
-	for i := 0; i < b.N; i++ {
-		obj := v1.Pod{}
-		if err := iter.Unmarshal(encoded[i%width], &obj); err != nil {
-			b.Fatal(err)
-		}
-	}
-	b.StopTimer()
-}
-
 // BenchmarkEncodeYAMLMarshal provides a baseline for regular YAML encode performance
 func BenchmarkEncodeYAMLMarshal(b *testing.B) {
 	items := benchmarkItems(b)
diff --git a/pkg/api/testing/unstructured_test.go b/pkg/api/testing/unstructured_test.go
index 21c6373056c..2f0f46d637c 100644
--- a/pkg/api/testing/unstructured_test.go
+++ b/pkg/api/testing/unstructured_test.go
@@ -19,12 +19,10 @@ package testing
 import (
 	"math/rand"
 	"reflect"
-	"sort"
 	"testing"
 
 	"github.com/google/go-cmp/cmp"
 	fuzz "github.com/google/gofuzz"
-	jsoniter "github.com/json-iterator/go"
 
 	v1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/api/apitesting/fuzzer"
@@ -260,75 +258,3 @@ func BenchmarkFromUnstructuredViaJSON(b *testing.B) {
 	}
 	b.StopTimer()
 }
-
-func BenchmarkToUnstructuredViaJSONIter(b *testing.B) {
-	items := benchmarkItems(b)
-	size := len(items)
-	var keys []string
-	for k := range jsonIterConfig {
-		keys = append(keys, k)
-	}
-	sort.Strings(keys)
-	for _, name := range keys {
-		c := jsonIterConfig[name]
-		b.Run(name, func(b *testing.B) {
-			b.ResetTimer()
-			for i := 0; i < b.N; i++ {
-				data, err := c.Marshal(&items[i%size])
-				if err != nil {
-					b.Fatalf("unexpected error: %v", err)
-				}
-				unstr := map[string]interface{}{}
-				if err := c.Unmarshal(data, &unstr); err != nil {
-					b.Fatalf("unexpected error: %v", err)
-				}
-			}
-			b.StopTimer()
-		})
-	}
-}
-
-var jsonIterConfig = map[string]jsoniter.API{
-	"default": jsoniter.ConfigDefault,
-	"fastest": jsoniter.ConfigFastest,
-	"compat":  jsoniter.ConfigCompatibleWithStandardLibrary,
-}
-
-func BenchmarkFromUnstructuredViaJSONIter(b *testing.B) {
-	items := benchmarkItems(b)
-	var unstr []map[string]interface{}
-	for i := range items {
-		data, err := jsoniter.Marshal(&items[i])
-		if err != nil {
-			b.Fatalf("unexpected error: %v", err)
-		}
-		item := map[string]interface{}{}
-		if err := json.Unmarshal(data, &item); err != nil {
-			b.Fatalf("unexpected error: %v", err)
-		}
-		unstr = append(unstr, item)
-	}
-	size := len(items)
-	var keys []string
-	for k := range jsonIterConfig {
-		keys = append(keys, k)
-	}
-	sort.Strings(keys)
-	for _, name := range keys {
-		c := jsonIterConfig[name]
-		b.Run(name, func(b *testing.B) {
-			b.ResetTimer()
-			for i := 0; i < b.N; i++ {
-				item, err := c.Marshal(unstr[i%size])
-				if err != nil {
-					b.Fatalf("unexpected error: %v", err)
-				}
-				obj := v1.Pod{}
-				if err := c.Unmarshal(item, &obj); err != nil {
-					b.Fatalf("unexpected error: %v", err)
-				}
-			}
-			b.StopTimer()
-		})
-	}
-}
diff --git a/pkg/scheduler/apis/config/scheme/scheme_test.go b/pkg/scheduler/apis/config/scheme/scheme_test.go
index fca416ede0c..dbb514c3f7b 100644
--- a/pkg/scheduler/apis/config/scheme/scheme_test.go
+++ b/pkg/scheduler/apis/config/scheme/scheme_test.go
@@ -263,7 +263,7 @@ profiles:
           - Score: 2
             Utilization: 1
 `),
-			wantErr: `decoding .profiles[0].pluginConfig[0]: decoding args for plugin NodeResourcesFit: strict decoder error for {"scoringStrategy":{"requestedToCapacityRatio":{"shape":[{"Score":2,"Utilization":1}]}}}: v1beta2.NodeResourcesFitArgs.ScoringStrategy: v1beta2.ScoringStrategy.RequestedToCapacityRatio: v1beta2.RequestedToCapacityRatioParam.Shape: []v1beta2.UtilizationShapePoint: v1beta2.UtilizationShapePoint.ReadObject: found unknown field: Score, error found in #10 byte of ...|:[{"Score":2,"Utiliz|..., bigger context ...|gy":{"requestedToCapacityRatio":{"shape":[{"Score":2,"Utilization":1}]}}}|...`,
+			wantErr: `decoding .profiles[0].pluginConfig[0]: decoding args for plugin NodeResourcesFit: strict decoding error: unknown field "Score", unknown field "Utilization"`,
 		},
 		{
 			name: "v1beta2 NodeResourcesFitArgs resources encoding is strict",
@@ -279,7 +279,7 @@ profiles:
         - Name: cpu
           Weight: 1
 `),
-			wantErr: `decoding .profiles[0].pluginConfig[0]: decoding args for plugin NodeResourcesFit: strict decoder error for {"scoringStrategy":{"resources":[{"Name":"cpu","Weight":1}]}}: v1beta2.NodeResourcesFitArgs.ScoringStrategy: v1beta2.ScoringStrategy.Resources: []v1beta2.ResourceSpec: v1beta2.ResourceSpec.ReadObject: found unknown field: Name, error found in #10 byte of ...|":[{"Name":"cpu","We|..., bigger context ...|{"scoringStrategy":{"resources":[{"Name":"cpu","Weight":1}]}}|...`,
+			wantErr: `decoding .profiles[0].pluginConfig[0]: decoding args for plugin NodeResourcesFit: strict decoding error: unknown field "Name", unknown field "Weight"`,
 		},
 		{
 			name: "out-of-tree plugin args",
@@ -604,7 +604,7 @@ profiles:
           - Score: 2
             Utilization: 1
 `),
-			wantErr: `decoding .profiles[0].pluginConfig[0]: decoding args for plugin NodeResourcesFit: strict decoder error for {"scoringStrategy":{"requestedToCapacityRatio":{"shape":[{"Score":2,"Utilization":1}]}}}: v1beta3.NodeResourcesFitArgs.ScoringStrategy: v1beta3.ScoringStrategy.RequestedToCapacityRatio: v1beta3.RequestedToCapacityRatioParam.Shape: []v1beta3.UtilizationShapePoint: v1beta3.UtilizationShapePoint.ReadObject: found unknown field: Score, error found in #10 byte of ...|:[{"Score":2,"Utiliz|..., bigger context ...|gy":{"requestedToCapacityRatio":{"shape":[{"Score":2,"Utilization":1}]}}}|...`,
+			wantErr: `decoding .profiles[0].pluginConfig[0]: decoding args for plugin NodeResourcesFit: strict decoding error: unknown field "Score", unknown field "Utilization"`,
 		},
 		{
 			name: "v1beta3 NodeResourcesFitArgs resources encoding is strict",
@@ -620,7 +620,7 @@ profiles:
         - Name: cpu
           Weight: 1
 `),
-			wantErr: `decoding .profiles[0].pluginConfig[0]: decoding args for plugin NodeResourcesFit: strict decoder error for {"scoringStrategy":{"resources":[{"Name":"cpu","Weight":1}]}}: v1beta3.NodeResourcesFitArgs.ScoringStrategy: v1beta3.ScoringStrategy.Resources: []v1beta3.ResourceSpec: v1beta3.ResourceSpec.ReadObject: found unknown field: Name, error found in #10 byte of ...|":[{"Name":"cpu","We|..., bigger context ...|{"scoringStrategy":{"resources":[{"Name":"cpu","Weight":1}]}}|...`,
+			wantErr: `decoding .profiles[0].pluginConfig[0]: decoding args for plugin NodeResourcesFit: strict decoding error: unknown field "Name", unknown field "Weight"`,
 		},
 		{
 			name: "out-of-tree plugin args",
diff --git a/staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/objectmeta/coerce.go b/staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/objectmeta/coerce.go
index 39850e3d20e..d9c486c37ef 100644
--- a/staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/objectmeta/coerce.go
+++ b/staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/objectmeta/coerce.go
@@ -22,11 +22,9 @@ import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/runtime"
-	"k8s.io/apimachinery/pkg/runtime/serializer/json"
+	utiljson "k8s.io/apimachinery/pkg/util/json"
 )
 
-var encodingjson = json.CaseSensitiveJSONIterator()
-
 // GetObjectMeta does conversion of JSON to ObjectMeta. It first tries json.Unmarshal into a metav1.ObjectMeta
 // type. If that does not work and dropMalformedFields is true, it does field-by-field best-effort conversion
 // throwing away fields which lead to errors.
@@ -38,11 +36,11 @@ func GetObjectMeta(obj map[string]interface{}, dropMalformedFields bool) (*metav
 
 	// round-trip through JSON first, hoping that unmarshalling just works
 	objectMeta := &metav1.ObjectMeta{}
-	metadataBytes, err := encodingjson.Marshal(metadata)
+	metadataBytes, err := utiljson.Marshal(metadata)
 	if err != nil {
 		return nil, false, err
 	}
-	if err = encodingjson.Unmarshal(metadataBytes, objectMeta); err == nil {
+	if err = utiljson.Unmarshal(metadataBytes, objectMeta); err == nil {
 		// if successful, return
 		return objectMeta, true, nil
 	}
@@ -63,11 +61,11 @@ func GetObjectMeta(obj map[string]interface{}, dropMalformedFields bool) (*metav
 	testObjectMeta := &metav1.ObjectMeta{}
 	for k, v := range metadataMap {
 		// serialize a single field
-		if singleFieldBytes, err := encodingjson.Marshal(map[string]interface{}{k: v}); err == nil {
+		if singleFieldBytes, err := utiljson.Marshal(map[string]interface{}{k: v}); err == nil {
 			// do a test unmarshal
-			if encodingjson.Unmarshal(singleFieldBytes, testObjectMeta) == nil {
+			if utiljson.Unmarshal(singleFieldBytes, testObjectMeta) == nil {
 				// if that succeeds, unmarshal for real
-				encodingjson.Unmarshal(singleFieldBytes, accumulatedObjectMeta)
+				utiljson.Unmarshal(singleFieldBytes, accumulatedObjectMeta)
 			}
 		}
 	}
diff --git a/staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/objectmeta/coerce_test.go b/staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/objectmeta/coerce_test.go
index 8f844752d43..c72240146fe 100644
--- a/staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/objectmeta/coerce_test.go
+++ b/staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/objectmeta/coerce_test.go
@@ -31,6 +31,7 @@ import (
 	"k8s.io/apimachinery/pkg/runtime/serializer"
 	"k8s.io/apimachinery/pkg/runtime/serializer/json"
 	"k8s.io/apimachinery/pkg/util/diff"
+	utiljson "k8s.io/apimachinery/pkg/util/json"
 	clientgoscheme "k8s.io/client-go/kubernetes/scheme"
 )
 
@@ -114,12 +115,12 @@ func TestMalformedObjectMetaFields(t *testing.T) {
 				}
 
 				// See if it can unmarshal to object meta
-				spuriousJSON, err := encodingjson.Marshal(spuriousMetaMap)
+				spuriousJSON, err := utiljson.Marshal(spuriousMetaMap)
 				if err != nil {
 					t.Fatalf("error on %v=%#v: %v", pth, v, err)
 				}
 				expectedObjectMeta := &metav1.ObjectMeta{}
-				if err := encodingjson.Unmarshal(spuriousJSON, expectedObjectMeta); err != nil {
+				if err := utiljson.Unmarshal(spuriousJSON, expectedObjectMeta); err != nil {
 					// if standard json unmarshal would fail decoding this field, drop the field entirely
 					truncatedMetaMap, err := runtime.DefaultUnstructuredConverter.ToUnstructured(fuzzedObjectMeta.DeepCopy())
 					if err != nil {
@@ -133,12 +134,12 @@ func TestMalformedObjectMetaFields(t *testing.T) {
 						DeleteJSONPath(truncatedMetaMap, pth[:1], 0)
 					}
 
-					truncatedJSON, err := encodingjson.Marshal(truncatedMetaMap)
+					truncatedJSON, err := utiljson.Marshal(truncatedMetaMap)
 					if err != nil {
 						t.Fatalf("error on %v=%#v: %v", pth, v, err)
 					}
 					expectedObjectMeta = &metav1.ObjectMeta{}
-					if err := encodingjson.Unmarshal(truncatedJSON, expectedObjectMeta); err != nil {
+					if err := utiljson.Unmarshal(truncatedJSON, expectedObjectMeta); err != nil {
 						t.Fatalf("error on %v=%#v: %v", pth, v, err)
 					}
 				}
@@ -190,7 +191,7 @@ func TestGetObjectMetaNils(t *testing.T) {
 	}
 
 	// double check this what the kube JSON decode is doing
-	bs, _ := encodingjson.Marshal(u.UnstructuredContent())
+	bs, _ := utiljson.Marshal(u.UnstructuredContent())
 	kubeObj, _, err := clientgoscheme.Codecs.UniversalDecoder(corev1.SchemeGroupVersion).Decode(bs, nil, nil)
 	if err != nil {
 		t.Fatal(err)
diff --git a/staging/src/k8s.io/apimachinery/pkg/apis/meta/v1/group_version_test.go b/staging/src/k8s.io/apimachinery/pkg/apis/meta/v1/group_version_test.go
index 0ad415cf86e..c50a1902ecc 100644
--- a/staging/src/k8s.io/apimachinery/pkg/apis/meta/v1/group_version_test.go
+++ b/staging/src/k8s.io/apimachinery/pkg/apis/meta/v1/group_version_test.go
@@ -21,7 +21,7 @@ import (
 	"reflect"
 	"testing"
 
-	"k8s.io/apimachinery/pkg/runtime/serializer/json"
+	utiljson "k8s.io/apimachinery/pkg/util/json"
 )
 
 type GroupVersionHolder struct {
@@ -46,13 +46,12 @@ func TestGroupVersionUnmarshalJSON(t *testing.T) {
 		if !reflect.DeepEqual(result.GV, c.expect) {
 			t.Errorf("JSON codec failed to unmarshal input '%s': expected %+v, got %+v", c.input, c.expect, result.GV)
 		}
-		// test the json-iterator codec
-		iter := json.CaseSensitiveJSONIterator()
-		if err := iter.Unmarshal(c.input, &result); err != nil {
-			t.Errorf("json-iterator codec failed to unmarshal input '%v': %v", c.input, err)
+		// test the utiljson codec
+		if err := utiljson.Unmarshal(c.input, &result); err != nil {
+			t.Errorf("util/json codec failed to unmarshal input '%v': %v", c.input, err)
 		}
 		if !reflect.DeepEqual(result.GV, c.expect) {
-			t.Errorf("json-iterator codec failed to unmarshal input '%s': expected %+v, got %+v", c.input, c.expect, result.GV)
+			t.Errorf("util/json codec failed to unmarshal input '%s': expected %+v, got %+v", c.input, c.expect, result.GV)
 		}
 	}
 }
diff --git a/staging/src/k8s.io/apimachinery/pkg/apis/meta/v1/types_test.go b/staging/src/k8s.io/apimachinery/pkg/apis/meta/v1/types_test.go
index 648e8b58a40..f216527ddb7 100644
--- a/staging/src/k8s.io/apimachinery/pkg/apis/meta/v1/types_test.go
+++ b/staging/src/k8s.io/apimachinery/pkg/apis/meta/v1/types_test.go
@@ -21,7 +21,7 @@ import (
 	"reflect"
 	"testing"
 
-	"k8s.io/apimachinery/pkg/runtime/serializer/json"
+	utiljson "k8s.io/apimachinery/pkg/util/json"
 )
 
 func TestVerbsMarshalJSON(t *testing.T) {
@@ -56,10 +56,9 @@ func TestVerbsJsonIterUnmarshalJSON(t *testing.T) {
 		{`{"verbs":["delete"]}`, APIResource{Verbs: Verbs([]string{"delete"})}},
 	}
 
-	iter := json.CaseSensitiveJSONIterator()
 	for i, c := range cases {
 		var result APIResource
-		if err := iter.Unmarshal([]byte(c.input), &result); err != nil {
+		if err := utiljson.Unmarshal([]byte(c.input), &result); err != nil {
 			t.Errorf("[%d] Failed to unmarshal input '%v': %v", i, c.input, err)
 		}
 		if !reflect.DeepEqual(result, c.result) {
diff --git a/staging/src/k8s.io/apimachinery/pkg/runtime/converter_test.go b/staging/src/k8s.io/apimachinery/pkg/runtime/converter_test.go
index 224b2838ba5..a96778628e6 100644
--- a/staging/src/k8s.io/apimachinery/pkg/runtime/converter_test.go
+++ b/staging/src/k8s.io/apimachinery/pkg/runtime/converter_test.go
@@ -274,7 +274,7 @@ func TestRoundTrip(t *testing.T) {
 		{
 			// Test slice of interface{} with different values.
 			obj: &D{
-				A: []interface{}{3.0, "3.0", nil},
+				A: []interface{}{float64(3.5), int64(4), "3.0", nil},
 			},
 		},
 	}
@@ -322,11 +322,11 @@ func TestUnrecognized(t *testing.T) {
 		err  error
 	}{
 		{
-			data: "{\"da\":[3.0,\"3.0\",null]}",
+			data: "{\"da\":[3.5,4,\"3.0\",null]}",
 			obj:  &D{},
 		},
 		{
-			data: "{\"ea\":[3.0,\"3.0\",null]}",
+			data: "{\"ea\":[3.5,4,\"3.0\",null]}",
 			obj:  &E{},
 		},
 		{
diff --git a/staging/src/k8s.io/apimachinery/pkg/runtime/error.go b/staging/src/k8s.io/apimachinery/pkg/runtime/error.go
index be0c5edc855..55e8b5ac269 100644
--- a/staging/src/k8s.io/apimachinery/pkg/runtime/error.go
+++ b/staging/src/k8s.io/apimachinery/pkg/runtime/error.go
@@ -19,6 +19,7 @@ package runtime
 import (
 	"fmt"
 	"reflect"
+	"strings"
 
 	"k8s.io/apimachinery/pkg/runtime/schema"
 )
@@ -124,20 +125,26 @@ func IsMissingVersion(err error) bool {
 // strictDecodingError is a base error type that is returned by a strict Decoder such
 // as UniversalStrictDecoder.
 type strictDecodingError struct {
-	message string
-	data    string
+	errors []error
 }
 
 // NewStrictDecodingError creates a new strictDecodingError object.
-func NewStrictDecodingError(message string, data string) error {
+func NewStrictDecodingError(errors []error) error {
 	return &strictDecodingError{
-		message: message,
-		data:    data,
+		errors: errors,
 	}
 }
 
 func (e *strictDecodingError) Error() string {
-	return fmt.Sprintf("strict decoder error for %s: %s", e.data, e.message)
+	var s strings.Builder
+	s.WriteString("strict decoding error: ")
+	for i, err := range e.errors {
+		if i != 0 {
+			s.WriteString(", ")
+		}
+		s.WriteString(err.Error())
+	}
+	return s.String()
 }
 
 // IsStrictDecodingError returns true if the error indicates that the provided object
diff --git a/staging/src/k8s.io/apimachinery/pkg/runtime/serializer/json/json.go b/staging/src/k8s.io/apimachinery/pkg/runtime/serializer/json/json.go
index 1bdf5a48f19..daf0ea59665 100644
--- a/staging/src/k8s.io/apimachinery/pkg/runtime/serializer/json/json.go
+++ b/staging/src/k8s.io/apimachinery/pkg/runtime/serializer/json/json.go
@@ -20,10 +20,8 @@ import (
 	"encoding/json"
 	"io"
 	"strconv"
-	"unsafe"
 
-	jsoniter "github.com/json-iterator/go"
-	"github.com/modern-go/reflect2"
+	kjson "sigs.k8s.io/json"
 	"sigs.k8s.io/yaml"
 
 	"k8s.io/apimachinery/pkg/runtime"
@@ -110,79 +108,6 @@ type Serializer struct {
 var _ runtime.Serializer = &Serializer{}
 var _ recognizer.RecognizingDecoder = &Serializer{}
 
-type customNumberExtension struct {
-	jsoniter.DummyExtension
-}
-
-func (cne *customNumberExtension) CreateDecoder(typ reflect2.Type) jsoniter.ValDecoder {
-	if typ.String() == "interface {}" {
-		return customNumberDecoder{}
-	}
-	return nil
-}
-
-type customNumberDecoder struct {
-}
-
-func (customNumberDecoder) Decode(ptr unsafe.Pointer, iter *jsoniter.Iterator) {
-	switch iter.WhatIsNext() {
-	case jsoniter.NumberValue:
-		var number jsoniter.Number
-		iter.ReadVal(&number)
-		i64, err := strconv.ParseInt(string(number), 10, 64)
-		if err == nil {
-			*(*interface{})(ptr) = i64
-			return
-		}
-		f64, err := strconv.ParseFloat(string(number), 64)
-		if err == nil {
-			*(*interface{})(ptr) = f64
-			return
-		}
-		iter.ReportError("DecodeNumber", err.Error())
-	default:
-		*(*interface{})(ptr) = iter.Read()
-	}
-}
-
-// CaseSensitiveJSONIterator returns a jsoniterator API that's configured to be
-// case-sensitive when unmarshalling, and otherwise compatible with
-// the encoding/json standard library.
-func CaseSensitiveJSONIterator() jsoniter.API {
-	config := jsoniter.Config{
-		EscapeHTML:             true,
-		SortMapKeys:            true,
-		ValidateJsonRawMessage: true,
-		CaseSensitive:          true,
-	}.Froze()
-	// Force jsoniter to decode number to interface{} via int64/float64, if possible.
-	config.RegisterExtension(&customNumberExtension{})
-	return config
-}
-
-// StrictCaseSensitiveJSONIterator returns a jsoniterator API that's configured to be
-// case-sensitive, but also disallows unknown fields when unmarshalling. It is compatible with
-// the encoding/json standard library.
-func StrictCaseSensitiveJSONIterator() jsoniter.API {
-	config := jsoniter.Config{
-		EscapeHTML:             true,
-		SortMapKeys:            true,
-		ValidateJsonRawMessage: true,
-		CaseSensitive:          true,
-		DisallowUnknownFields:  true,
-	}.Froze()
-	// Force jsoniter to decode number to interface{} via int64/float64, if possible.
-	config.RegisterExtension(&customNumberExtension{})
-	return config
-}
-
-// Private copies of jsoniter to try to shield against possible mutations
-// from outside. Still does not protect from package level jsoniter.Register*() functions - someone calling them
-// in some other library will mess with every usage of the jsoniter library in the whole program.
-// See https://github.com/json-iterator/go/issues/265
-var caseSensitiveJSONIterator = CaseSensitiveJSONIterator()
-var strictCaseSensitiveJSONIterator = StrictCaseSensitiveJSONIterator()
-
 // gvkWithDefaults returns group kind and version defaulting from provided default
 func gvkWithDefaults(actual, defaultGVK schema.GroupVersionKind) schema.GroupVersionKind {
 	if len(actual.Kind) == 0 {
@@ -237,7 +162,7 @@ func (s *Serializer) Decode(originalData []byte, gvk *schema.GroupVersionKind, i
 		types, _, err := s.typer.ObjectKinds(into)
 		switch {
 		case runtime.IsNotRegisteredError(err), isUnstructured:
-			if err := caseSensitiveJSONIterator.Unmarshal(data, into); err != nil {
+			if err := kjson.UnmarshalCaseSensitivePreserveInts(data, into); err != nil {
 				return nil, actual, err
 			}
 			return into, actual, nil
@@ -261,35 +186,35 @@ func (s *Serializer) Decode(originalData []byte, gvk *schema.GroupVersionKind, i
 		return nil, actual, err
 	}
 
-	if err := caseSensitiveJSONIterator.Unmarshal(data, obj); err != nil {
-		return nil, actual, err
-	}
-
-	// If the deserializer is non-strict, return successfully here.
+	// If the deserializer is non-strict, return here.
 	if !s.options.Strict {
+		if err := kjson.UnmarshalCaseSensitivePreserveInts(data, obj); err != nil {
+			return nil, actual, err
+		}
 		return obj, actual, nil
 	}
 
-	// In strict mode pass the data trough the YAMLToJSONStrict converter.
-	// This is done to catch duplicate fields regardless of encoding (JSON or YAML). For JSON data,
-	// the output would equal the input, unless there is a parsing error such as duplicate fields.
-	// As we know this was successful in the non-strict case, the only error that may be returned here
-	// is because of the newly-added strictness. hence we know we can return the typed strictDecoderError
-	// the actual error is that the object contains duplicate fields.
-	altered, err := yaml.YAMLToJSONStrict(originalData)
+	var allStrictErrs []error
+	if s.options.Yaml {
+		// In strict mode pass the original data through the YAMLToJSONStrict converter.
+		// This is done to catch duplicate fields in YAML that would have been dropped in the original YAMLToJSON conversion.
+		// TODO: rework YAMLToJSONStrict to return warnings about duplicate fields without terminating so we don't have to do this twice.
+		_, err := yaml.YAMLToJSONStrict(originalData)
+		if err != nil {
+			allStrictErrs = append(allStrictErrs, err)
+		}
+	}
+
+	strictJSONErrs, err := kjson.UnmarshalStrict(data, obj)
 	if err != nil {
-		return nil, actual, runtime.NewStrictDecodingError(err.Error(), string(originalData))
+		// fatal decoding error, not due to strictness
+		return nil, actual, err
 	}
-	// As performance is not an issue for now for the strict deserializer (one has regardless to do
-	// the unmarshal twice), we take the sanitized, altered data that is guaranteed to have no duplicated
-	// fields, and unmarshal this into a copy of the already-populated obj. Any error that occurs here is
-	// due to that a matching field doesn't exist in the object. hence we can return a typed strictDecoderError,
-	// the actual error is that the object contains unknown field.
-	strictObj := obj.DeepCopyObject()
-	if err := strictCaseSensitiveJSONIterator.Unmarshal(altered, strictObj); err != nil {
-		return nil, actual, runtime.NewStrictDecodingError(err.Error(), string(originalData))
+	allStrictErrs = append(allStrictErrs, strictJSONErrs...)
+	if len(allStrictErrs) > 0 {
+		// return the successfully decoded object along with the strict errors
+		return obj, actual, runtime.NewStrictDecodingError(allStrictErrs)
 	}
-	// Always return the same object as the non-strict serializer to avoid any deviations.
 	return obj, actual, nil
 }
 
diff --git a/staging/src/k8s.io/apimachinery/pkg/runtime/serializer/json/json_limit_test.go b/staging/src/k8s.io/apimachinery/pkg/runtime/serializer/json/json_limit_test.go
index a741541fb2e..8214d293c62 100644
--- a/staging/src/k8s.io/apimachinery/pkg/runtime/serializer/json/json_limit_test.go
+++ b/staging/src/k8s.io/apimachinery/pkg/runtime/serializer/json/json_limit_test.go
@@ -123,7 +123,6 @@ func testcases() []testcase {
 var decoders = map[string]func([]byte, interface{}) error{
 	"gojson":   gojson.Unmarshal,
 	"utiljson": utiljson.Unmarshal,
-	"jsoniter": CaseSensitiveJSONIterator().Unmarshal,
 }
 
 func TestJSONLimits(t *testing.T) {
diff --git a/staging/src/k8s.io/apimachinery/pkg/runtime/serializer/json/json_test.go b/staging/src/k8s.io/apimachinery/pkg/runtime/serializer/json/json_test.go
index aac6cc3f7c2..29a94609edd 100644
--- a/staging/src/k8s.io/apimachinery/pkg/runtime/serializer/json/json_test.go
+++ b/staging/src/k8s.io/apimachinery/pkg/runtime/serializer/json/json_test.go
@@ -39,8 +39,7 @@ type testDecodable struct {
 	Interface interface{}   `json:"interface"`
 }
 
-// DecodableSpec has 15 fields. json-iterator treats struct with more than 10
-// fields differently from struct that has less than 10 fields.
+// DecodableSpec has 15 fields.
 type DecodableSpec struct {
 	A int `json:"A"`
 	B int `json:"B"`
@@ -264,7 +263,7 @@ func TestDecode(t *testing.T) {
 			creater:     &mockCreater{obj: &testDecodable{}},
 			expectedGVK: &schema.GroupVersionKind{Kind: "Test", Group: "other", Version: "blah"},
 			errFn: func(err error) bool {
-				return strings.Contains(err.Error(), `json_test.testDecodable.Interface: DecodeNumber: strconv.ParseFloat: parsing "1e1000": value out of range`)
+				return strings.Contains(err.Error(), `json: cannot unmarshal number 1e1000 into Go struct field testDecodable.interface of type float64`)
 			},
 		},
 		// Unmarshalling is case-sensitive
@@ -298,7 +297,7 @@ func TestDecode(t *testing.T) {
 			typer:       &mockTyper{gvk: &schema.GroupVersionKind{Kind: "Test", Group: "other", Version: "blah"}},
 			expectedGVK: &schema.GroupVersionKind{Kind: "Test", Group: "other", Version: "blah"},
 			errFn: func(err error) bool {
-				return strings.Contains(err.Error(), "found unknown field")
+				return strings.Contains(err.Error(), `unknown field "unknown"`)
 			},
 			strict: true,
 		},
@@ -309,7 +308,7 @@ func TestDecode(t *testing.T) {
 			typer:       &mockTyper{gvk: &schema.GroupVersionKind{Kind: "Test", Group: "other", Version: "blah"}},
 			expectedGVK: &schema.GroupVersionKind{Kind: "Test", Group: "other", Version: "blah"},
 			errFn: func(err error) bool {
-				return strings.Contains(err.Error(), "found unknown field: unknown")
+				return strings.Contains(err.Error(), `unknown field "unknown"`)
 			},
 			yaml:   true,
 			strict: true,
@@ -321,7 +320,7 @@ func TestDecode(t *testing.T) {
 			typer:       &mockTyper{gvk: &schema.GroupVersionKind{Kind: "Test", Group: "other", Version: "blah"}},
 			expectedGVK: &schema.GroupVersionKind{Kind: "Test", Group: "other", Version: "blah"},
 			errFn: func(err error) bool {
-				return strings.Contains(err.Error(), `"value" already set in map`)
+				return strings.Contains(err.Error(), `duplicate field "value"`)
 			},
 			strict: true,
 		},
@@ -526,7 +525,7 @@ func TestDecode(t *testing.T) {
 			if !test.errFn(err) {
 				t.Errorf("%d: failed: %v", i, err)
 			}
-			if obj != nil {
+			if !runtime.IsStrictDecodingError(err) && obj != nil {
 				t.Errorf("%d: should have returned nil object", i)
 			}
 			continue
diff --git a/staging/src/k8s.io/apimachinery/pkg/util/json/json.go b/staging/src/k8s.io/apimachinery/pkg/util/json/json.go
index 778e58f704b..55dba361c36 100644
--- a/staging/src/k8s.io/apimachinery/pkg/util/json/json.go
+++ b/staging/src/k8s.io/apimachinery/pkg/util/json/json.go
@@ -17,10 +17,11 @@ limitations under the License.
 package json
 
 import (
-	"bytes"
 	"encoding/json"
 	"fmt"
 	"io"
+
+	kjson "sigs.k8s.io/json"
 )
 
 // NewEncoder delegates to json.NewEncoder
@@ -38,50 +39,11 @@ func Marshal(v interface{}) ([]byte, error) {
 // limit recursive depth to prevent stack overflow errors
 const maxDepth = 10000
 
-// Unmarshal unmarshals the given data
-// If v is a *map[string]interface{}, *[]interface{}, or *interface{} numbers
-// are converted to int64 or float64
+// Unmarshal unmarshals the given data.
+// Object keys are case-sensitive.
+// Numbers decoded into interface{} fields are converted to int64 or float64.
 func Unmarshal(data []byte, v interface{}) error {
-	switch v := v.(type) {
-	case *map[string]interface{}:
-		// Build a decoder from the given data
-		decoder := json.NewDecoder(bytes.NewBuffer(data))
-		// Preserve numbers, rather than casting to float64 automatically
-		decoder.UseNumber()
-		// Run the decode
-		if err := decoder.Decode(v); err != nil {
-			return err
-		}
-		// If the decode succeeds, post-process the map to convert json.Number objects to int64 or float64
-		return ConvertMapNumbers(*v, 0)
-
-	case *[]interface{}:
-		// Build a decoder from the given data
-		decoder := json.NewDecoder(bytes.NewBuffer(data))
-		// Preserve numbers, rather than casting to float64 automatically
-		decoder.UseNumber()
-		// Run the decode
-		if err := decoder.Decode(v); err != nil {
-			return err
-		}
-		// If the decode succeeds, post-process the map to convert json.Number objects to int64 or float64
-		return ConvertSliceNumbers(*v, 0)
-
-	case *interface{}:
-		// Build a decoder from the given data
-		decoder := json.NewDecoder(bytes.NewBuffer(data))
-		// Preserve numbers, rather than casting to float64 automatically
-		decoder.UseNumber()
-		// Run the decode
-		if err := decoder.Decode(v); err != nil {
-			return err
-		}
-		// If the decode succeeds, post-process the map to convert json.Number objects to int64 or float64
-		return ConvertInterfaceNumbers(v, 0)
-
-	default:
-		return json.Unmarshal(data, v)
-	}
+	return kjson.UnmarshalCaseSensitivePreserveInts(data, v)
 }
 
 // ConvertInterfaceNumbers converts any json.Number values to int64 or float64.
diff --git a/staging/src/k8s.io/apiserver/pkg/admission/plugin/webhook/mutating/dispatcher.go b/staging/src/k8s.io/apiserver/pkg/admission/plugin/webhook/mutating/dispatcher.go
index a419328f436..d73b220ec16 100644
--- a/staging/src/k8s.io/apiserver/pkg/admission/plugin/webhook/mutating/dispatcher.go
+++ b/staging/src/k8s.io/apiserver/pkg/admission/plugin/webhook/mutating/dispatcher.go
@@ -34,6 +34,7 @@ import (
 	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/serializer/json"
+	utiljson "k8s.io/apimachinery/pkg/util/json"
 	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
 	"k8s.io/apiserver/pkg/admission"
 	admissionmetrics "k8s.io/apiserver/pkg/admission/metrics"
@@ -61,8 +62,6 @@ const (
 	MutationAuditAnnotationFailedOpenKeyPrefix string = "failed-open." + MutationAuditAnnotationPrefix
 )
 
-var encodingjson = json.CaseSensitiveJSONIterator()
-
 type mutatingDispatcher struct {
 	cm     *webhookutil.ClientManager
 	plugin *Plugin
@@ -444,7 +443,7 @@ func mutationAnnotationValue(configuration, webhook string, mutated bool) (strin
 		Webhook:       webhook,
 		Mutated:       mutated,
 	}
-	bytes, err := encodingjson.Marshal(m)
+	bytes, err := utiljson.Marshal(m)
 	return string(bytes), err
 }
 
@@ -455,6 +454,6 @@ func jsonPatchAnnotationValue(configuration, webhook string, patch interface{})
 		Patch:         patch,
 		PatchType:     string(admissionv1.PatchTypeJSONPatch),
 	}
-	bytes, err := encodingjson.Marshal(p)
+	bytes, err := utiljson.Marshal(p)
 	return string(bytes), err
 }
diff --git a/staging/src/k8s.io/cli-runtime/pkg/resource/builder_test.go b/staging/src/k8s.io/cli-runtime/pkg/resource/builder_test.go
index 6a46454195d..bc6e3c66fb0 100644
--- a/staging/src/k8s.io/cli-runtime/pkg/resource/builder_test.go
+++ b/staging/src/k8s.io/cli-runtime/pkg/resource/builder_test.go
@@ -50,7 +50,7 @@ import (
 	utiltesting "k8s.io/client-go/util/testing"
 
 	// TODO we need to remove this linkage and create our own scheme
-	"k8s.io/api/core/v1"
+	v1 "k8s.io/api/core/v1"
 	"k8s.io/client-go/kubernetes/scheme"
 )
 
@@ -1762,7 +1762,7 @@ func TestUnstructured(t *testing.T) {
 		{
 			name:          "badpod",
 			file:          "badpod.json",
-			expectedError: "v1.ObjectMeta.Annotations",
+			expectedError: "ObjectMeta.",
 		},
 	}
 
diff --git a/staging/src/k8s.io/cli-runtime/pkg/resource/metadata_decoder.go b/staging/src/k8s.io/cli-runtime/pkg/resource/metadata_decoder.go
index 12770573e27..d688c3a08ae 100644
--- a/staging/src/k8s.io/cli-runtime/pkg/resource/metadata_decoder.go
+++ b/staging/src/k8s.io/cli-runtime/pkg/resource/metadata_decoder.go
@@ -20,12 +20,9 @@ import (
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
-	"k8s.io/apimachinery/pkg/runtime/serializer/json"
+	utiljson "k8s.io/apimachinery/pkg/util/json"
 )
 
-// hold a single instance of the case-sensitive decoder
-var caseSensitiveJsonIterator = json.CaseSensitiveJSONIterator()
-
 // metadataValidatingDecoder wraps a decoder and additionally ensures metadata schema fields decode before returning an unstructured object
 type metadataValidatingDecoder struct {
 	decoder runtime.Decoder
@@ -47,7 +44,7 @@ func (m *metadataValidatingDecoder) Decode(data []byte, defaults *schema.GroupVe
 	// make sure the data can decode into ObjectMeta before we return,
 	// so we don't silently truncate schema errors in metadata later with accesser get/set calls
 	v := &metadataOnlyObject{}
-	if typedErr := caseSensitiveJsonIterator.Unmarshal(data, v); typedErr != nil {
+	if typedErr := utiljson.Unmarshal(data, v); typedErr != nil {
 		return obj, gvk, typedErr
 	}
 	return obj, gvk, err
diff --git a/staging/src/k8s.io/kube-aggregator/pkg/controllers/openapi/aggregator/downloader.go b/staging/src/k8s.io/kube-aggregator/pkg/controllers/openapi/aggregator/downloader.go
index cdafa5a7496..a6c50907e82 100644
--- a/staging/src/k8s.io/kube-aggregator/pkg/controllers/openapi/aggregator/downloader.go
+++ b/staging/src/k8s.io/kube-aggregator/pkg/controllers/openapi/aggregator/downloader.go
@@ -22,8 +22,7 @@ import (
 	"net/http"
 	"strings"
 
-	jsoniter "github.com/json-iterator/go"
-
+	utiljson "k8s.io/apimachinery/pkg/util/json"
 	"k8s.io/apiserver/pkg/authentication/user"
 	"k8s.io/apiserver/pkg/endpoints/request"
 	"k8s.io/kube-openapi/pkg/validation/spec"
@@ -80,7 +79,7 @@ func (s *Downloader) Download(handler http.Handler, etag string) (returnSpec *sp
 		return nil, "", http.StatusNotFound, nil
 	case http.StatusOK:
 		openAPISpec := &spec.Swagger{}
-		if err := jsoniter.ConfigCompatibleWithStandardLibrary.Unmarshal(writer.data, openAPISpec); err != nil {
+		if err := utiljson.Unmarshal(writer.data, openAPISpec); err != nil {
 			return nil, "", 0, err
 		}
 		newEtag = writer.Header().Get("Etag")
diff --git a/staging/src/k8s.io/pod-security-admission/admission/api/load/load_test.go b/staging/src/k8s.io/pod-security-admission/admission/api/load/load_test.go
index f01f171dab4..11136c571ed 100644
--- a/staging/src/k8s.io/pod-security-admission/admission/api/load/load_test.go
+++ b/staging/src/k8s.io/pod-security-admission/admission/api/load/load_test.go
@@ -277,7 +277,7 @@ exemptions:
 "apiVersion":"pod-security.admission.config.k8s.io/v1alpha1",
 "kind":"PodSecurityConfiguration",
 "deflaults":{"enforce":"baseline"}}`),
-			expectErr: `unknown field: deflaults`,
+			expectErr: `unknown field "deflaults"`,
 		},
 	}