diff --git a/protocol/entities.go b/protocol/entities.go
index 814e608e..c1495337 100644
--- a/protocol/entities.go
+++ b/protocol/entities.go
@@ -33,7 +33,7 @@ type CredentialEntity struct {
 type RelyingPartyEntity struct {
 	CredentialEntity
 	// A unique identifier for the Relying Party entity, which sets the RP ID.
-	ID string `json:"id"`
+	ID string `json:"id,omitempty"`
 }
 
 // The UserEntity represents the PublicKeyCredentialUserEntity IDL and is used to supply additional user account
diff --git a/webauthn/types.go b/webauthn/types.go
index bb93f31a..482a5b21 100644
--- a/webauthn/types.go
+++ b/webauthn/types.go
@@ -27,6 +27,7 @@ type WebAuthn struct {
 // Config represents the WebAuthn configuration.
 type Config struct {
 	// RPID configures the Relying Party Server ID. This should generally be the origin without a scheme and port.
+	// If absent the browser will automatically determine this using standard conventions.
 	RPID string
 
 	// RPDisplayName configures the display name for the Relying Party Server. This can be any string.
@@ -101,20 +102,28 @@ func (config *Config) validate() error {
 		return fmt.Errorf(errFmtFieldEmpty, "RPDisplayName")
 	}
 
-	if len(config.RPID) == 0 {
-		return fmt.Errorf(errFmtFieldEmpty, "RPID")
-	}
-
 	var err error
 
-	if _, err = url.Parse(config.RPID); err != nil {
-		return fmt.Errorf(errFmtFieldNotValidURI, "RPID", err)
+	var uri *url.URL
+
+	if len(config.RPID) != 0 {
+		if uri, err = url.Parse(config.RPID); err != nil {
+			return fmt.Errorf(errFmtFieldNotValidURI, "RPID", err)
+		}
+
+		if uri.IsAbs() {
+			return fmt.Errorf("field '%s' is an absolute URI but it must not be an absolute URI", "RPID")
+		}
 	}
 
-	if config.RPIcon != "" {
-		if _, err = url.Parse(config.RPIcon); err != nil {
+	if len(config.RPIcon) != 0 {
+		if uri, err = url.Parse(config.RPIcon); err != nil {
 			return fmt.Errorf(errFmtFieldNotValidURI, "RPIcon", err)
 		}
+
+		if !uri.IsAbs() {
+			return fmt.Errorf("field '%s' is not an absolute URI but it must be an absolute URI", "RPIcon")
+		}
 	}
 
 	defaultTimeoutConfig := defaultTimeout
@@ -141,7 +150,7 @@ func (config *Config) validate() error {
 		config.Timeouts.Registration.TimeoutUVD = defaultTimeoutUVDConfig
 	}
 
-	if len(config.RPOrigin) > 0 {
+	if len(config.RPOrigin) != 0 {
 		if len(config.RPOrigins) != 0 {
 			return fmt.Errorf("deprecated field 'RPOrigin' can't be defined at the same tme as the replacement field 'RPOrigins'")
 		}
diff --git a/webauthn/types_test.go b/webauthn/types_test.go
new file mode 100644
index 00000000..e0d41fdb
--- /dev/null
+++ b/webauthn/types_test.go
@@ -0,0 +1,182 @@
+package webauthn
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestConfigValidateErr(t *testing.T) {
+	testCases := []struct {
+		name  string
+		have  *Config
+		err   string
+		check func(t *testing.T, have *Config)
+	}{
+		{
+			"ShouldNotErrorOnStandardConfig",
+			&Config{
+				RPID:          "example.com",
+				RPDisplayName: "example",
+				RPOrigins: []string{
+					"https://example.com",
+				},
+			},
+			"",
+			nil,
+		},
+		{
+			"ShouldErrorOnAbsoluteRPID",
+			&Config{
+				RPID:          "https://example.com",
+				RPDisplayName: "example",
+				RPOrigins: []string{
+					"https://example.com",
+				},
+			},
+			"field 'RPID' is an absolute URI but it must not be an absolute URI",
+			nil,
+		},
+		{
+			"ShouldSkipValidation",
+			&Config{
+				validated: true,
+			},
+			"",
+			nil,
+		},
+		{
+			"ShouldErrorOnBadRPIcon",
+			&Config{
+				RPID:          "example.com",
+				RPIcon:        "exa$##$#@$@#%^@#mple.com",
+				RPDisplayName: "example",
+				RPOrigins: []string{
+					"https://example.com",
+				},
+			},
+			"field 'RPIcon' is not a valid URI: parse \"exa$##$#@$@#%^@#mple.com\": invalid URL escape \"%^@\"",
+			nil,
+		},
+		{
+			"ShouldErrorOnBadRPIconAbsolute",
+			&Config{
+				RPID:          "example.com",
+				RPIcon:        "example.com",
+				RPDisplayName: "example",
+				RPOrigins: []string{
+					"https://example.com",
+				},
+			},
+			"field 'RPIcon' is not an absolute URI but it must be an absolute URI",
+			nil,
+		},
+		{
+			"ShouldSetFallbackRPOriginAndNotErr",
+			&Config{
+				RPID:          "example.com",
+				RPDisplayName: "example",
+				RPOrigin:      "https://example.com",
+				RPOrigins:     []string{},
+			},
+			"",
+			func(t *testing.T, have *Config) {
+				require.Len(t, have.RPOrigins, 1)
+				assert.Equal(t, "https://example.com", have.RPOrigins[0])
+			},
+		},
+		{
+			"ShouldNotErrorOnConfigWithoutRPID",
+			&Config{
+				RPDisplayName: "example",
+				RPOrigins: []string{
+					"https://example.com",
+				},
+			},
+			"",
+			nil,
+		},
+		{
+			"ShouldErrorOnNoDisplayName",
+			&Config{
+				RPID: "example.com",
+				RPOrigins: []string{
+					"https://example.com",
+				},
+			},
+			"the field 'RPDisplayName' must be configured but it is empty",
+			nil,
+		},
+		{
+			"ShouldErrorOnNoOrigins",
+			&Config{
+				RPID:          "example.com",
+				RPDisplayName: "example",
+				RPOrigins:     []string{},
+			},
+			"must provide at least one value to the 'RPOrigins' field",
+			nil,
+		},
+		{
+			"ShouldErrorOnInvalidRPID",
+			&Config{
+				RPID:          "exa$##$#@$@#%^@#mple.com",
+				RPDisplayName: "example",
+				RPOrigins: []string{
+					"https://example.com",
+				},
+			},
+			"field 'RPID' is not a valid URI: parse \"exa$##$#@$@#%^@#mple.com\": invalid URL escape \"%^@\"",
+			nil,
+		},
+		{
+			"ShouldErrorOnDeprecatedAndNewRPOrigins",
+			&Config{
+				RPID:          "example.com",
+				RPDisplayName: "example",
+				RPOrigin:      "https://example.com",
+				RPOrigins: []string{
+					"https://example.com",
+				},
+			},
+			"deprecated field 'RPOrigin' can't be defined at the same tme as the replacement field 'RPOrigins'",
+			nil,
+		},
+		{
+			"ShouldSetDefaultTimeoutValues",
+			&Config{
+				RPID:          "example.com",
+				RPDisplayName: "example",
+				RPOrigins: []string{
+					"https://example.com",
+				},
+				Timeout: int(time.Second.Milliseconds()),
+			},
+			"",
+			func(t *testing.T, have *Config) {
+				assert.Equal(t, time.Second, have.Timeouts.Login.Timeout)
+				assert.Equal(t, time.Second, have.Timeouts.Login.TimeoutUVD)
+				assert.Equal(t, time.Second, have.Timeouts.Registration.Timeout)
+				assert.Equal(t, time.Second, have.Timeouts.Registration.TimeoutUVD)
+			},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			err := tc.have.validate()
+
+			if len(tc.err) == 0 {
+				assert.NoError(t, err)
+			} else {
+				assert.EqualError(t, err, tc.err)
+			}
+
+			if tc.check != nil {
+				tc.check(t, tc.have)
+			}
+		})
+	}
+}