diff --git a/app/validators/username_validator.go b/app/validators/username_validator.go
new file mode 100644
index 0000000..2d2dd84
--- /dev/null
+++ b/app/validators/username_validator.go
@@ -0,0 +1,21 @@
+package validators
+
+import (
+	"regexp"
+
+	. "github.com/reiver/greatape/components/constants"
+)
+
+func UsernameIsValid(username string) bool {
+	if !regexp.MustCompile(USERNAME).MatchString(username) {
+		return false
+	}
+
+	for _, reservedUsername := range ReservedUsernames {
+		if username == reservedUsername {
+			return false
+		}
+	}
+
+	return true
+}
diff --git a/app/validators/username_validator_test.go b/app/validators/username_validator_test.go
new file mode 100644
index 0000000..b455e20
--- /dev/null
+++ b/app/validators/username_validator_test.go
@@ -0,0 +1,84 @@
+package validators_test
+
+import (
+	"testing"
+
+	"github.com/reiver/greatape/app/validators"
+)
+
+func TestUsernameValidator(test *testing.T) {
+	type arguments struct {
+		username string
+	}
+
+	testCases := []struct {
+		name        string
+		expectation bool
+		arguments   arguments
+	}{
+		{
+			"Case1",
+			false,
+			arguments{
+				username: "",
+			},
+		},
+		{
+			"Case2",
+			false,
+			arguments{
+				username: "admin",
+			},
+		},
+		{
+			"Case3",
+			true,
+			arguments{
+				username: "johnny",
+			},
+		},
+		{
+			"Case4",
+			false,
+			arguments{
+				username: "webmaster",
+			},
+		},
+		{
+			"Case5",
+			true,
+			arguments{
+				username: "susan235",
+			},
+		},
+		{
+			"Case6",
+			true,
+			arguments{
+				username: "new_user",
+			},
+		},
+		{
+			"Case7",
+			true,
+			arguments{
+				username: "someone",
+			},
+		},
+		{
+			"Case8",
+			true,
+			arguments{
+				username: "north10star",
+			},
+		},
+	}
+
+	for _, testCase := range testCases {
+		test.Run(testCase.name, func(test *testing.T) {
+			if result := validators.UsernameIsValid(testCase.arguments.username); result != testCase.expectation {
+				test.Errorf("UsernameIsValid() = %v, expected %v", result, testCase.expectation)
+			}
+		})
+	}
+}