diff --git a/pkg/yqlib/doc/Keys.md b/pkg/yqlib/doc/Keys.md
new file mode 100644
index 0000000..b92293e
--- /dev/null
+++ b/pkg/yqlib/doc/Keys.md
@@ -0,0 +1,38 @@
+
+## Get Keys
+Given a sample.yml file of:
+```yaml
+a:
+  b: cat
+  c: dog
+  d: frog
+```
+then
+```bash
+yq eval '.a | keys' sample.yml
+```
+will output
+```yaml
+3
+```
+
+## Set key style
+Given a sample.yml file of:
+```yaml
+a:
+  b: cat
+  c: dog
+  d: frog
+```
+then
+```bash
+yq eval '(.a | keys) style = 'single'' sample.yml
+```
+will output
+```yaml
+a:
+  b: cat
+  c: dog
+  d: frog
+```
+
diff --git a/pkg/yqlib/lib.go b/pkg/yqlib/lib.go
index 56ae648..f2b93bf 100644
--- a/pkg/yqlib/lib.go
+++ b/pkg/yqlib/lib.go
@@ -49,6 +49,7 @@ var CreateMap = &OperationType{Type: "CREATE_MAP", NumArgs: 2, Precedence: 40, H
 var ShortPipe = &OperationType{Type: "SHORT_PIPE", NumArgs: 2, Precedence: 45, Handler: PipeOperator}
 
 var Length = &OperationType{Type: "LENGTH", NumArgs: 0, Precedence: 50, Handler: LengthOperator}
+var Keys = &OperationType{Type: "KEYS", NumArgs: 0, Precedence: 50, Handler: KeysOperator}
 var Collect = &OperationType{Type: "COLLECT", NumArgs: 0, Precedence: 50, Handler: CollectOperator}
 var GetStyle = &OperationType{Type: "GET_STYLE", NumArgs: 0, Precedence: 50, Handler: GetStyleOperator}
 var GetTag = &OperationType{Type: "GET_TAG", NumArgs: 0, Precedence: 50, Handler: GetTagOperator}
diff --git a/pkg/yqlib/operator_keys.go b/pkg/yqlib/operator_keys.go
new file mode 100644
index 0000000..3aa455b
--- /dev/null
+++ b/pkg/yqlib/operator_keys.go
@@ -0,0 +1,34 @@
+package yqlib
+
+import (
+	"container/list"
+	"fmt"
+
+	yaml "gopkg.in/yaml.v3"
+)
+
+func KeysOperator(d *dataTreeNavigator, matchMap *list.List, pathNode *PathTreeNode) (*list.List, error) {
+	log.Debugf("-- KeyOperation")
+	var results = list.New()
+
+	for el := matchMap.Front(); el != nil; el = el.Next() {
+		candidate := el.Value.(*CandidateNode)
+		targetNode := UnwrapDoc(candidate.Node)
+
+		switch targetNode.Kind {
+		case yaml.MappingNode:
+			node := &yaml.Node{Kind: yaml.SequenceNode, Value: fmt.Sprintf("%v", length), Tag: "!!int"}
+
+		case yaml.SequenceNode:
+			length = len(targetNode.Content)
+		default:
+			length = 0
+		}
+
+		node := &yaml.Node{Kind: yaml.ScalarNode, Value: fmt.Sprintf("%v", length), Tag: "!!int"}
+		lengthCand := &CandidateNode{Node: node, Document: candidate.Document, Path: candidate.Path}
+		results.PushBack(lengthCand)
+	}
+
+	return results, nil
+}
diff --git a/pkg/yqlib/operator_keys_test.go b/pkg/yqlib/operator_keys_test.go
new file mode 100644
index 0000000..93e788f
--- /dev/null
+++ b/pkg/yqlib/operator_keys_test.go
@@ -0,0 +1,88 @@
+package yqlib
+
+import (
+	"testing"
+)
+
+var keyOperatorScenarios = []expressionScenario{
+	{
+		description: "Get Keys of map",
+		document:    `{a: {b: cat, c: dog, d: frog}}`,
+		expression:  `.a | keys`,
+		expected: []string{
+			"D0, P[a], (!!seq)::- b\n- c\n- d\n",
+		},
+	},
+	{
+		skipDoc:    true,
+		document:   `{a1: {b: cat, c: dog, d: frog}, a2: {e: cat, f: dog, g: frog}}`,
+		expression: `(.a1, .a2) | keys`,
+		expected: []string{
+			"D0, P[a1], (!!seq)::- b\n- c\n- d\n",
+			"D0, P[a2], (!!seq)::- e\n- f\n- g\n",
+		},
+	},
+	{
+		description: "Get Keys of array",
+		document:    `{a: [0,1,2]}`,
+		expression:  `.a | keys`,
+		expected: []string{
+			"D0, P[a], (!!seq)::0\n",
+			"D0, P[a], (!!int)::1\n",
+			"D0, P[a], (!!int)::2\n",
+		},
+	},
+	{
+		description: "Set key style",
+		document:    `{a: {b: cat, c: dog, d: frog}}`,
+		expression:  `(.a | keys | ..) style = 'single'`,
+		expected: []string{
+			"D0, P[], (!!doc)::{a: {'b': cat, 'c': dog, 'd': frog}}\n",
+		},
+	},
+	{
+		description: "Set key alias",
+		document:    `{a: {b: cat, c: dog, d: frog}}`,
+		expression:  `(.a | keys | .. | select(.=="b")) alias = 'boo'`,
+		expected: []string{
+			"D0, P[], (!!doc)::{a: {*meow: cat, c: dog, d: frog}}\n",
+		},
+	},
+	{
+		description: "Set key alias",
+		document:    `{a: {b: cat, c: dog, d: frog}}`,
+		expression:  `(.a | key("b")) alias = 'boo'`,
+		expected: []string{
+			"D0, P[], (!!doc)::{a: {*meow: cat, c: dog, d: frog}}\n",
+		},
+	},
+	{
+		skipDoc:    true,
+		document:   `{a: [0,1,2]}`,
+		expression: `(.a | keys) style = 'single'`,
+		expected: []string{
+			"D0, P[a], (!!int)::0\n",
+			"D0, P[a], (!!int)::1\n",
+			"D0, P[a], (!!int)::2\n",
+		},
+	},
+	{
+		skipDoc:    true,
+		document:   `a: cat`,
+		expression: `.a | keys`,
+		expected:   []string{},
+	},
+	{
+		skipDoc:    true,
+		document:   `{}`,
+		expression: `.a | keys`,
+		expected:   []string{},
+	},
+}
+
+func TestKeyOperatorScenarios(t *testing.T) {
+	for _, tt := range keyOperatorScenarios {
+		testScenario(t, &tt)
+	}
+	documentScenarios(t, "Keys", keyOperatorScenarios)
+}
diff --git a/pkg/yqlib/path_tokeniser.go b/pkg/yqlib/path_tokeniser.go
index 9a6b1ed..39c8f7a 100644
--- a/pkg/yqlib/path_tokeniser.go
+++ b/pkg/yqlib/path_tokeniser.go
@@ -182,6 +182,7 @@ func initLexer() (*lex.Lexer, error) {
 	lexer.Add([]byte(`,`), opToken(Union))
 	lexer.Add([]byte(`:\s*`), opToken(CreateMap))
 	lexer.Add([]byte(`length`), opToken(Length))
+	lexer.Add([]byte(`keys`), opToken(Keys))
 	lexer.Add([]byte(`sortKeys`), opToken(SortKeys))
 	lexer.Add([]byte(`select`), opToken(Select))
 	lexer.Add([]byte(`has`), opToken(Has))
diff --git a/pkg/yqlib/test.yml b/pkg/yqlib/test.yml
new file mode 100644
index 0000000..4106642
--- /dev/null
+++ b/pkg/yqlib/test.yml
@@ -0,0 +1,10 @@
+{
+  "a1": {
+    "b": "cat",
+    "c": "dog"
+  },
+  "a2": {
+    "d": "cat",
+    "e": "dog"
+  }
+}
\ No newline at end of file