diff --git a/spring-web/src/main/java/org/springframework/web/util/UriComponentsBuilder.java b/spring-web/src/main/java/org/springframework/web/util/UriComponentsBuilder.java
index 409588bd8ebb..028d0e8695f3 100644
--- a/spring-web/src/main/java/org/springframework/web/util/UriComponentsBuilder.java
+++ b/spring-web/src/main/java/org/springframework/web/util/UriComponentsBuilder.java
@@ -518,9 +518,9 @@ private UriComponentsBuilder whatWgUrlRecord(WhatWgUrlParser.UrlRecord record) {
 			}
 			path(record.path().toString());
 			query(record.query());
-			if (StringUtils.hasText(record.fragment())) {
-				fragment(record.fragment());
-			}
+		}
+		if (StringUtils.hasText(record.fragment())) {
+			fragment(record.fragment());
 		}
 		return this;
 	}
diff --git a/spring-web/src/test/java/org/springframework/web/util/UriComponentsBuilderTests.java b/spring-web/src/test/java/org/springframework/web/util/UriComponentsBuilderTests.java
index d40ef9a918a4..f97457b5c63e 100644
--- a/spring-web/src/test/java/org/springframework/web/util/UriComponentsBuilderTests.java
+++ b/spring-web/src/test/java/org/springframework/web/util/UriComponentsBuilderTests.java
@@ -27,9 +27,12 @@
 import java.util.function.BiConsumer;
 
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.EnumSource;
 
 import org.springframework.util.LinkedMultiValueMap;
 import org.springframework.util.MultiValueMap;
+import org.springframework.web.util.UriComponentsBuilder.ParserType;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
@@ -47,8 +50,9 @@
  */
 class UriComponentsBuilderTests {
 
-	@Test  // see gh-26453
-	void examplesInReferenceManual() {
+	@ParameterizedTest // see gh-26453
+	@EnumSource(value = ParserType.class)
+	void examplesInReferenceManual(ParserType parserType) {
 		final String expected = "/hotel%20list/New%20York?q=foo%2Bbar";
 
 		URI uri = UriComponentsBuilder.fromPath("/hotel list/{city}")
@@ -63,7 +67,7 @@ void examplesInReferenceManual() {
 			.build("New York", "foo+bar");
 		assertThat(uri).asString().isEqualTo(expected);
 
-		uri = UriComponentsBuilder.fromUriString("/hotel list/{city}?q={q}")
+		uri = UriComponentsBuilder.fromUriString("/hotel list/{city}?q={q}", parserType)
 			.build("New York", "foo+bar");
 		assertThat(uri).asString().isEqualTo(expected);
 	}
@@ -150,19 +154,21 @@ void fromOpaqueUri() {
 		assertThat(result.toUri()).as("Invalid result URI").isEqualTo(uri);
 	}
 
-	@Test  // SPR-9317
-	void fromUriEncodedQuery() {
+	@ParameterizedTest // see gh-9317
+	@EnumSource(value = ParserType.class)
+	void fromUriEncodedQuery(ParserType parserType) {
 		URI uri = URI.create("https://www.example.org/?param=aGVsbG9Xb3JsZA%3D%3D");
 		String fromUri = UriComponentsBuilder.fromUri(uri).build().getQueryParams().get("param").get(0);
-		String fromUriString = UriComponentsBuilder.fromUriString(uri.toString())
+		String fromUriString = UriComponentsBuilder.fromUriString(uri.toString(), parserType)
 				.build().getQueryParams().get("param").get(0);
 
 		assertThat(fromUriString).isEqualTo(fromUri);
 	}
 
-	@Test
-	void fromUriString() {
-		UriComponents result = UriComponentsBuilder.fromUriString("https://www.ietf.org/rfc/rfc3986.txt").build();
+	@ParameterizedTest
+	@EnumSource(value = ParserType.class)
+	void fromUriString(ParserType parserType) {
+		UriComponents result = UriComponentsBuilder.fromUriString("https://www.ietf.org/rfc/rfc3986.txt", parserType).build();
 		assertThat(result.getScheme()).isEqualTo("https");
 		assertThat(result.getUserInfo()).isNull();
 		assertThat(result.getHost()).isEqualTo("www.ietf.org");
@@ -174,7 +180,7 @@ void fromUriString() {
 
 		String url = "https://arjen:foobar@java.sun.com:80" +
 				"/javase/6/docs/api/java/util/BitSet.html?foo=bar#and(java.util.BitSet)";
-		result = UriComponentsBuilder.fromUriString(url).build();
+		result = UriComponentsBuilder.fromUriString(url, parserType).build();
 		assertThat(result.getScheme()).isEqualTo("https");
 		assertThat(result.getUserInfo()).isEqualTo("arjen:foobar");
 		assertThat(result.getHost()).isEqualTo("java.sun.com");
@@ -186,7 +192,7 @@ void fromUriString() {
 		assertThat(result.getQueryParams()).isEqualTo(expectedQueryParams);
 		assertThat(result.getFragment()).isEqualTo("and(java.util.BitSet)");
 
-		result = UriComponentsBuilder.fromUriString("mailto:java-net@java.sun.com#baz").build();
+		result = UriComponentsBuilder.fromUriString("mailto:java-net@java.sun.com#baz", parserType).build();
 		assertThat(result.getScheme()).isEqualTo("mailto");
 		assertThat(result.getUserInfo()).isNull();
 		assertThat(result.getHost()).isNull();
@@ -196,7 +202,7 @@ void fromUriString() {
 		assertThat(result.getQuery()).isNull();
 		assertThat(result.getFragment()).isEqualTo("baz");
 
-		result = UriComponentsBuilder.fromUriString("mailto:user@example.com?subject=foo").build();
+		result = UriComponentsBuilder.fromUriString("mailto:user@example.com?subject=foo", parserType).build();
 		assertThat(result.getScheme()).isEqualTo("mailto");
 		assertThat(result.getUserInfo()).isNull();
 		assertThat(result.getHost()).isNull();
@@ -206,7 +212,7 @@ void fromUriString() {
 		assertThat(result.getQuery()).isNull();
 		assertThat(result.getFragment()).isNull();
 
-		result = UriComponentsBuilder.fromUriString("docs/guide/collections/designfaq.html#28").build();
+		result = UriComponentsBuilder.fromUriString("docs/guide/collections/designfaq.html#28", parserType).build();
 		assertThat(result.getScheme()).isNull();
 		assertThat(result.getUserInfo()).isNull();
 		assertThat(result.getHost()).isNull();
@@ -216,69 +222,80 @@ void fromUriString() {
 		assertThat(result.getFragment()).isEqualTo("28");
 	}
 
-	@Test  // SPR-9832
-	void fromUriStringQueryParamWithReservedCharInValue() {
+	@ParameterizedTest // see SPR-9832
+	@EnumSource(value = ParserType.class)
+	void fromUriStringQueryParamWithReservedCharInValue(ParserType parserType) {
 		String uri = "https://www.google.com/ig/calculator?q=1USD=?EUR";
-		UriComponents result = UriComponentsBuilder.fromUriString(uri).build();
+		UriComponents result = UriComponentsBuilder.fromUriString(uri, parserType).build();
 
 		assertThat(result.getQuery()).isEqualTo("q=1USD=?EUR");
 		assertThat(result.getQueryParams().getFirst("q")).isEqualTo("1USD=?EUR");
 	}
 
-	@Test  // SPR-14828
-	void fromUriStringQueryParamEncodedAndContainingPlus() {
+	@ParameterizedTest // see SPR-14828
+	@EnumSource(value = ParserType.class)
+	void fromUriStringQueryParamEncodedAndContainingPlus(ParserType parserType) {
 		String httpUrl = "http://localhost:8080/test/print?value=%EA%B0%80+%EB%82%98";
-		URI uri = UriComponentsBuilder.fromUriString(httpUrl).build(true).toUri();
+		URI uri = UriComponentsBuilder.fromUriString(httpUrl, parserType).build(true).toUri();
 
 		assertThat(uri.toString()).isEqualTo(httpUrl);
 	}
 
-	@Test  // SPR-10539
-	void fromUriStringIPv6Host() {
+	@ParameterizedTest // see SPR-10539
+	@EnumSource(value = ParserType.class)
+	void fromUriStringIPv6Host(ParserType parserType) {
 		UriComponents result = UriComponentsBuilder
-				.fromUriString("http://[1abc:2abc:3abc::5ABC:6abc]:8080/resource").build().encode();
+				.fromUriString("http://[1abc:2abc:3abc::5ABC:6abc]:8080/resource", parserType).build().encode();
 		assertThat(result.getHost()).isEqualToIgnoringCase("[1abc:2abc:3abc::5ABC:6abc]");
 	}
 
-	@Test
-	void fromUriStringInvalidIPv6Host() {
+	@ParameterizedTest
+	@EnumSource(value = ParserType.class)
+	void fromUriStringInvalidIPv6Host(ParserType parserType) {
 		assertThatIllegalArgumentException().isThrownBy(() ->
-				UriComponentsBuilder.fromUriString("http://[1abc:2abc:3abc::5ABC:6abc:8080/resource"));
+				UriComponentsBuilder.fromUriString("http://[1abc:2abc:3abc::5ABC:6abc:8080/resource", parserType));
 	}
 
-	@Test  // SPR-11970
-	void fromUriStringNoPathWithReservedCharInQuery() {
-		UriComponents result = UriComponentsBuilder.fromUriString("https://example.com?foo=bar@baz").build();
+	@ParameterizedTest // see SPR-11970
+	@EnumSource(value = ParserType.class)
+	void fromUriStringNoPathWithReservedCharInQuery(ParserType parserType) {
+		UriComponents result = UriComponentsBuilder.fromUriString("https://example.com?foo=bar@baz", parserType).build();
 		assertThat(result.getUserInfo()).isNull();
 		assertThat(result.getHost()).isEqualTo("example.com");
 		assertThat(result.getQueryParams()).containsKey("foo");
 		assertThat(result.getQueryParams().getFirst("foo")).isEqualTo("bar@baz");
 	}
 
-	@Test  // SPR-14828
-	void fromHttpUrlQueryParamEncodedAndContainingPlus() {
+	@ParameterizedTest // see SPR-1428
+	@EnumSource(value = ParserType.class)
+	void fromHttpUrlQueryParamEncodedAndContainingPlus(ParserType parserType) {
 		String httpUrl = "http://localhost:8080/test/print?value=%EA%B0%80+%EB%82%98";
-		URI uri = UriComponentsBuilder.fromUriString(httpUrl).build(true).toUri();
+		URI uri = UriComponentsBuilder.fromUriString(httpUrl, parserType).build(true).toUri();
 
 		assertThat(uri.toString()).isEqualTo(httpUrl);
 	}
 
-	@Test  // SPR-10779
-	void fromHttpUrlCaseInsensitiveScheme() {
-		assertThat(UriComponentsBuilder.fromUriString("HTTP://www.google.com").build().getScheme()).isEqualTo("http");
-		assertThat(UriComponentsBuilder.fromUriString("HTTPS://www.google.com").build().getScheme()).isEqualTo("https");
+	@ParameterizedTest // see SPR-10779
+	@EnumSource(value = ParserType.class)
+	void fromHttpUrlCaseInsensitiveScheme(ParserType parserType) {
+		assertThat(UriComponentsBuilder.fromUriString("HTTP://www.google.com", parserType).build().getScheme())
+				.isEqualTo("http");
+		assertThat(UriComponentsBuilder.fromUriString("HTTPS://www.google.com", parserType).build().getScheme())
+				.isEqualTo("https");
 	}
 
-	@Test  // SPR-10539
-	void fromHttpUrlInvalidIPv6Host() {
+	@ParameterizedTest // see SPR-10539
+	@EnumSource(value = ParserType.class)
+	void fromHttpUrlInvalidIPv6Host(ParserType parserType) {
 		assertThatIllegalArgumentException().isThrownBy(() ->
-				UriComponentsBuilder.fromUriString("http://[1abc:2abc:3abc::5ABC:6abc:8080/resource"));
+				UriComponentsBuilder.fromUriString("http://[1abc:2abc:3abc::5ABC:6abc:8080/resource", parserType));
 	}
 
-	@Test
-	void fromHttpUrlWithoutFragment() {
+	@ParameterizedTest
+	@EnumSource(value = ParserType.class)
+	void fromHttpUrlWithoutFragment(ParserType parserType) {
 		String httpUrl = "http://localhost:8080/test/print";
-		UriComponents uriComponents = UriComponentsBuilder.fromUriString(httpUrl).build();
+		UriComponents uriComponents = UriComponentsBuilder.fromUriString(httpUrl, parserType).build();
 		assertThat(uriComponents.getScheme()).isEqualTo("http");
 		assertThat(uriComponents.getUserInfo()).isNull();
 		assertThat(uriComponents.getHost()).isEqualTo("localhost");
@@ -290,7 +307,7 @@ void fromHttpUrlWithoutFragment() {
 		assertThat(uriComponents.toUri().toString()).isEqualTo(httpUrl);
 
 		httpUrl = "http://user:test@localhost:8080/test/print?foo=bar";
-		uriComponents = UriComponentsBuilder.fromUriString(httpUrl).build();
+		uriComponents = UriComponentsBuilder.fromUriString(httpUrl, parserType).build();
 		assertThat(uriComponents.getScheme()).isEqualTo("http");
 		assertThat(uriComponents.getUserInfo()).isEqualTo("user:test");
 		assertThat(uriComponents.getHost()).isEqualTo("localhost");
@@ -302,7 +319,7 @@ void fromHttpUrlWithoutFragment() {
 		assertThat(uriComponents.toUri().toString()).isEqualTo(httpUrl);
 
 		httpUrl = "http://localhost:8080/test/print?foo=bar";
-		uriComponents = UriComponentsBuilder.fromUriString(httpUrl).build();
+		uriComponents = UriComponentsBuilder.fromUriString(httpUrl, parserType).build();
 		assertThat(uriComponents.getScheme()).isEqualTo("http");
 		assertThat(uriComponents.getUserInfo()).isNull();
 		assertThat(uriComponents.getHost()).isEqualTo("localhost");
@@ -314,10 +331,11 @@ void fromHttpUrlWithoutFragment() {
 		assertThat(uriComponents.toUri().toString()).isEqualTo(httpUrl);
 	}
 
-	@Test  // gh-25300
-	void fromHttpUrlWithFragment() {
+	@ParameterizedTest // see gh-25300
+	@EnumSource(value = ParserType.class)
+	void fromHttpUrlWithFragment(ParserType parserType) {
 		String httpUrl = "https://example.com/#baz";
-		UriComponents uriComponents = UriComponentsBuilder.fromUriString(httpUrl).build();
+		UriComponents uriComponents = UriComponentsBuilder.fromUriString(httpUrl, parserType).build();
 		assertThat(uriComponents.getScheme()).isEqualTo("https");
 		assertThat(uriComponents.getUserInfo()).isNull();
 		assertThat(uriComponents.getHost()).isEqualTo("example.com");
@@ -329,7 +347,7 @@ void fromHttpUrlWithFragment() {
 		assertThat(uriComponents.toUri().toString()).isEqualTo(httpUrl);
 
 		httpUrl = "http://localhost:8080/test/print#baz";
-		uriComponents = UriComponentsBuilder.fromUriString(httpUrl).build();
+		uriComponents = UriComponentsBuilder.fromUriString(httpUrl, parserType).build();
 		assertThat(uriComponents.getScheme()).isEqualTo("http");
 		assertThat(uriComponents.getUserInfo()).isNull();
 		assertThat(uriComponents.getHost()).isEqualTo("localhost");
@@ -341,7 +359,7 @@ void fromHttpUrlWithFragment() {
 		assertThat(uriComponents.toUri().toString()).isEqualTo(httpUrl);
 
 		httpUrl = "http://localhost:8080/test/print?foo=bar#baz";
-		uriComponents = UriComponentsBuilder.fromUriString(httpUrl).build();
+		uriComponents = UriComponentsBuilder.fromUriString(httpUrl, parserType).build();
 		assertThat(uriComponents.getScheme()).isEqualTo("http");
 		assertThat(uriComponents.getUserInfo()).isNull();
 		assertThat(uriComponents.getHost()).isEqualTo("localhost");
@@ -429,30 +447,32 @@ void pathWithDuplicateSlashes() {
 		assertThat(uriComponents.getPath()).isEqualTo("/foo/bar");
 	}
 
-	@Test
-	void replacePath() {
-		UriComponentsBuilder builder = UriComponentsBuilder.fromUriString("https://www.ietf.org/rfc/rfc2396.txt");
+	@ParameterizedTest
+	@EnumSource(value = ParserType.class)
+	void replacePath(ParserType parserType) {
+		UriComponentsBuilder builder = UriComponentsBuilder.fromUriString("https://www.ietf.org/rfc/rfc2396.txt", parserType);
 		builder.replacePath("/rfc/rfc3986.txt");
 		UriComponents result = builder.build();
 
 		assertThat(result.toUriString()).isEqualTo("https://www.ietf.org/rfc/rfc3986.txt");
 
-		builder = UriComponentsBuilder.fromUriString("https://www.ietf.org/rfc/rfc2396.txt");
+		builder = UriComponentsBuilder.fromUriString("https://www.ietf.org/rfc/rfc2396.txt", parserType);
 		builder.replacePath(null);
 		result = builder.build();
 
 		assertThat(result.toUriString()).isEqualTo("https://www.ietf.org");
 	}
 
-	@Test
-	void replaceQuery() {
-		UriComponentsBuilder builder = UriComponentsBuilder.fromUriString("https://example.com/foo?foo=bar&baz=qux");
+	@ParameterizedTest
+	@EnumSource(value = ParserType.class)
+	void replaceQuery(ParserType parserType) {
+		UriComponentsBuilder builder = UriComponentsBuilder.fromUriString("https://example.com/foo?foo=bar&baz=qux", parserType);
 		builder.replaceQuery("baz=42");
 		UriComponents result = builder.build();
 
 		assertThat(result.toUriString()).isEqualTo("https://example.com/foo?baz=42");
 
-		builder = UriComponentsBuilder.fromUriString("https://example.com/foo?foo=bar&baz=qux");
+		builder = UriComponentsBuilder.fromUriString("https://example.com/foo?foo=bar&baz=qux", parserType);
 		builder.replaceQuery(null);
 		result = builder.build();
 
@@ -583,36 +603,40 @@ void buildAndExpandHierarchical() {
 		assertThat(result.toUriString()).isEqualTo("/fooValue/barValue");
 	}
 
-	@Test
-	void buildAndExpandOpaque() {
-		UriComponents result = UriComponentsBuilder.fromUriString("mailto:{user}@{domain}")
+	@ParameterizedTest
+	@EnumSource(value = ParserType.class)
+	void buildAndExpandOpaque(ParserType parserType) {
+		UriComponents result = UriComponentsBuilder.fromUriString("mailto:{user}@{domain}", parserType)
 				.buildAndExpand("foo", "example.com");
 		assertThat(result.toUriString()).isEqualTo("mailto:foo@example.com");
 
 		Map<String, String> values = new HashMap<>();
 		values.put("user", "foo");
 		values.put("domain", "example.com");
-		UriComponentsBuilder.fromUriString("mailto:{user}@{domain}").buildAndExpand(values);
+		UriComponentsBuilder.fromUriString("mailto:{user}@{domain}", parserType).buildAndExpand(values);
 		assertThat(result.toUriString()).isEqualTo("mailto:foo@example.com");
 	}
 
-	@Test
-	void queryParamWithValueWithEquals() {
-		UriComponents uriComponents = UriComponentsBuilder.fromUriString("https://example.com/foo?bar=baz").build();
+	@ParameterizedTest
+	@EnumSource(value = ParserType.class)
+	void queryParamWithValueWithEquals(ParserType parserType) {
+		UriComponents uriComponents = UriComponentsBuilder.fromUriString("https://example.com/foo?bar=baz", parserType).build();
 		assertThat(uriComponents.toUriString()).isEqualTo("https://example.com/foo?bar=baz");
 		assertThat(uriComponents.getQueryParams().get("bar")).containsExactly("baz");
 	}
 
-	@Test
-	void queryParamWithoutValueWithEquals() {
-		UriComponents uriComponents = UriComponentsBuilder.fromUriString("https://example.com/foo?bar=").build();
+	@ParameterizedTest
+	@EnumSource(value = ParserType.class)
+	void queryParamWithoutValueWithEquals(ParserType parserType) {
+		UriComponents uriComponents = UriComponentsBuilder.fromUriString("https://example.com/foo?bar=", parserType).build();
 		assertThat(uriComponents.toUriString()).isEqualTo("https://example.com/foo?bar=");
 		assertThat(uriComponents.getQueryParams().get("bar")).element(0).asString().isEmpty();
 	}
 
-	@Test
-	void queryParamWithoutValueWithoutEquals() {
-		UriComponents uriComponents = UriComponentsBuilder.fromUriString("https://example.com/foo?bar").build();
+	@ParameterizedTest
+	@EnumSource(value = ParserType.class)
+	void queryParamWithoutValueWithoutEquals(ParserType parserType) {
+		UriComponents uriComponents = UriComponentsBuilder.fromUriString("https://example.com/foo?bar", parserType).build();
 		assertThat(uriComponents.toUriString()).isEqualTo("https://example.com/foo?bar");
 
 		// TODO [SPR-13537] Change equalTo(null) to equalTo("").
@@ -634,46 +658,50 @@ void opaqueUriDoesNotResetOnNullInput() {
 		assertThat(result.toUri()).isEqualTo(uri);
 	}
 
-	@Test
-	void relativeUrls() {
+	@ParameterizedTest
+	@EnumSource(value = ParserType.class)
+	void relativeUrls(ParserType parserType) {
 		String baseUrl = "https://example.com";
-		assertThat(UriComponentsBuilder.fromUriString(baseUrl + "/foo/../bar").build().toString())
-				.isEqualTo(baseUrl + "/foo/../bar");
-		assertThat(UriComponentsBuilder.fromUriString(baseUrl + "/foo/../bar").build().toUriString())
-				.isEqualTo(baseUrl + "/foo/../bar");
-		assertThat(UriComponentsBuilder.fromUriString(baseUrl + "/foo/../bar").build().toUri().getPath())
-				.isEqualTo("/foo/../bar");
-		assertThat(UriComponentsBuilder.fromUriString(baseUrl).path("foo/../bar").build().toString())
+		assertThat(UriComponentsBuilder.fromUriString(baseUrl + "/foo/../bar", parserType).build().toString())
+				.isEqualTo(baseUrl + (parserType == ParserType.WHAT_WG ? "/bar" : "/foo/../bar"));
+		assertThat(UriComponentsBuilder.fromUriString(baseUrl + "/foo/../bar", parserType).build().toUriString())
+				.isEqualTo(baseUrl + (parserType == ParserType.WHAT_WG ? "/bar" : "/foo/../bar"));
+		assertThat(UriComponentsBuilder.fromUriString(baseUrl + "/foo/../bar", parserType).build().toUri().getPath())
+				.isEqualTo((parserType == ParserType.WHAT_WG ? "/bar" : "/foo/../bar"));
+		assertThat(UriComponentsBuilder.fromUriString(baseUrl, parserType).path("foo/../bar").build().toString())
 				.isEqualTo(baseUrl + "/foo/../bar");
-		assertThat(UriComponentsBuilder.fromUriString(baseUrl).path("foo/../bar").build().toUriString())
+		assertThat(UriComponentsBuilder.fromUriString(baseUrl, parserType).path("foo/../bar").build().toUriString())
 				.isEqualTo(baseUrl + "/foo/../bar");
-		assertThat(UriComponentsBuilder.fromUriString(baseUrl).path("foo/../bar").build().toUri().getPath())
+		assertThat(UriComponentsBuilder.fromUriString(baseUrl, parserType).path("foo/../bar").build().toUri().getPath())
 				.isEqualTo("/foo/../bar");
 	}
 
-	@Test
-	void emptySegments() {
+	@ParameterizedTest
+	@EnumSource(value = ParserType.class)
+	void emptySegments(ParserType parserType) {
 		String baseUrl = "https://example.com/abc/";
-		assertThat(UriComponentsBuilder.fromUriString(baseUrl).path("/x/y/z").build().toString())
+		assertThat(UriComponentsBuilder.fromUriString(baseUrl, parserType).path("/x/y/z").build().toString())
 				.isEqualTo("https://example.com/abc/x/y/z");
-		assertThat(UriComponentsBuilder.fromUriString(baseUrl).pathSegment("x", "y", "z").build().toString())
+		assertThat(UriComponentsBuilder.fromUriString(baseUrl, parserType).pathSegment("x", "y", "z").build().toString())
 				.isEqualTo("https://example.com/abc/x/y/z");
-		assertThat(UriComponentsBuilder.fromUriString(baseUrl).path("/x/").path("/y/z").build().toString())
+		assertThat(UriComponentsBuilder.fromUriString(baseUrl, parserType).path("/x/").path("/y/z").build().toString())
 				.isEqualTo("https://example.com/abc/x/y/z");
-		assertThat(UriComponentsBuilder.fromUriString(baseUrl).pathSegment("x").path("y").build().toString())
+		assertThat(UriComponentsBuilder.fromUriString(baseUrl, parserType).pathSegment("x").path("y").build().toString())
 				.isEqualTo("https://example.com/abc/x/y");
 	}
 
-	@Test
-	void parsesEmptyFragment() {
-		UriComponents components = UriComponentsBuilder.fromUriString("/example#").build();
+	@ParameterizedTest
+	@EnumSource(value = ParserType.class)
+	void parsesEmptyFragment(ParserType parserType) {
+		UriComponents components = UriComponentsBuilder.fromUriString("/example#", parserType).build();
 		assertThat(components.getFragment()).isNull();
 		assertThat(components.toString()).isEqualTo("/example");
 	}
 
-	@Test  // SPR-13257
-	void parsesEmptyUri() {
-		UriComponents components = UriComponentsBuilder.fromUriString("").build();
+	@ParameterizedTest // SPR-13257
+	@EnumSource(value = ParserType.class)
+	void parsesEmptyUri(ParserType parserType) {
+		UriComponents components = UriComponentsBuilder.fromUriString("", parserType).build();
 		assertThat(components.toString()).isEmpty();
 	}
 
@@ -733,17 +761,18 @@ void testDeepClone() {
 		assertThat(result1.getSchemeSpecificPart()).isNull();
 	}
 
-	@Test // gh-26466
-	void encodeTemplateWithInvalidPlaceholderSyntax() {
+	@ParameterizedTest // gh-26466
+	@EnumSource(value = ParserType.class)
+	void encodeTemplateWithInvalidPlaceholderSyntax(ParserType parserType) {
 
 		BiConsumer<String, String> tester = (in, out) ->
-				assertThat(UriComponentsBuilder.fromUriString(in).encode().toUriString()).isEqualTo(out);
+				assertThat(UriComponentsBuilder.fromUriString(in, parserType).encode().toUriString()).isEqualTo(out);
 
 		// empty
 		tester.accept("{}", "%7B%7D");
-		tester.accept("{ \t}", "%7B%20%09%7D");
+		tester.accept("{ \t}", (parserType == ParserType.WHAT_WG ? "%7B%20%7D" : "%7B%20%09%7D"));
 		tester.accept("/a{}b", "/a%7B%7Db");
-		tester.accept("/a{ \t}b", "/a%7B%20%09%7Db");
+		tester.accept("/a{ \t}b", (parserType == ParserType.WHAT_WG ? "/a%7B%20%7Db" : "/a%7B%20%09%7Db"));
 
 		// nested, matching
 		tester.accept("{foo{}}", "%7Bfoo%7B%7D%7D");
@@ -762,28 +791,32 @@ void encodeTemplateWithInvalidPlaceholderSyntax() {
 		tester.accept("/a{year:\\d{1,4}}b", "/a{year:\\d{1,4}}b");
 	}
 
-	@Test  // SPR-16364
-	void uriComponentsNotEqualAfterNormalization() {
-		UriComponents uri1 = UriComponentsBuilder.fromUriString("http://test.com").build().normalize();
-		UriComponents uri2 = UriComponentsBuilder.fromUriString("http://test.com/").build();
+	@ParameterizedTest // SPR-16364
+	@EnumSource(value = ParserType.class)
+	void uriComponentsNotEqualAfterNormalization(ParserType parserType) {
+		UriComponents uri1 = UriComponentsBuilder.fromUriString("http://test.com", parserType).build().normalize();
+		UriComponents uri2 = UriComponentsBuilder.fromUriString("http://test.com/", parserType).build();
 
 		assertThat(uri1.getPathSegments()).isEmpty();
 		assertThat(uri2.getPathSegments()).isEmpty();
 		assertThat(uri2).isNotEqualTo(uri1);
 	}
 
-	@Test  // SPR-17256
-	void uriComponentsWithMergedQueryParams() {
-		String uri = UriComponentsBuilder.fromUriString("http://localhost:8081")
-				.uriComponents(UriComponentsBuilder.fromUriString("/{path}?sort={sort}").build())
+	@ParameterizedTest // SPR-17256
+	@EnumSource(value = ParserType.class)
+	void uriComponentsWithMergedQueryParams(ParserType parserType) {
+		String uri = UriComponentsBuilder.fromUriString("http://localhost:8081", parserType)
+				.uriComponents(UriComponentsBuilder.fromUriString("/{path}?sort={sort}", parserType).build())
 				.queryParam("sort", "another_value").build().toString();
 
 		assertThat(uri).isEqualTo("http://localhost:8081/{path}?sort={sort}&sort=another_value");
 	}
 
-	@Test  // SPR-17630
-	void toUriStringWithCurlyBraces() {
-		assertThat(UriComponentsBuilder.fromUriString("/path?q={asa}asa").toUriString()).isEqualTo("/path?q=%7Basa%7Dasa");
+	@ParameterizedTest // SPR-17630
+	@EnumSource(value = ParserType.class)
+	void toUriStringWithCurlyBraces(ParserType parserType) {
+		assertThat(UriComponentsBuilder.fromUriString("/path?q={asa}asa", parserType).toUriString())
+				.isEqualTo("/path?q=%7Basa%7Dasa");
 	}
 
 	@Test  // gh-26012
@@ -792,34 +825,37 @@ void verifyDoubleSlashReplacedWithSingleOne() {
 		assertThat(path).isEqualTo("/home/path");
 	}
 
-	@Test
-	void validPort() {
-		UriComponents uriComponents = UriComponentsBuilder.fromUriString("http://localhost:52567/path").build();
+	@ParameterizedTest
+	@EnumSource(value = ParserType.class)
+	void validPort(ParserType parserType) {
+		UriComponents uriComponents = UriComponentsBuilder.fromUriString("http://localhost:52567/path", parserType).build();
 		assertThat(uriComponents.getPort()).isEqualTo(52567);
 		assertThat(uriComponents.getPath()).isEqualTo("/path");
 
-		uriComponents = UriComponentsBuilder.fromUriString("http://localhost:52567?trace=false").build();
+		uriComponents = UriComponentsBuilder.fromUriString("http://localhost:52567?trace=false", parserType).build();
 		assertThat(uriComponents.getPort()).isEqualTo(52567);
 		assertThat(uriComponents.getQuery()).isEqualTo("trace=false");
 
-		uriComponents = UriComponentsBuilder.fromUriString("http://localhost:52567#fragment").build();
+		uriComponents = UriComponentsBuilder.fromUriString("http://localhost:52567#fragment", parserType).build();
 		assertThat(uriComponents.getPort()).isEqualTo(52567);
 		assertThat(uriComponents.getFragment()).isEqualTo("fragment");
 	}
 
-	@Test
-	void verifyInvalidPort() {
+	@ParameterizedTest
+	@EnumSource(value = ParserType.class)
+	void verifyInvalidPort(ParserType parserType) {
 		String url = "http://localhost:XXX/path";
 		assertThatIllegalArgumentException()
-				.isThrownBy(() -> UriComponentsBuilder.fromUriString(url).build().toUri());
+				.isThrownBy(() -> UriComponentsBuilder.fromUriString(url, parserType).build().toUri());
 		assertThatIllegalArgumentException()
-				.isThrownBy(() -> UriComponentsBuilder.fromUriString(url).build().toUri());
+				.isThrownBy(() -> UriComponentsBuilder.fromUriString(url, parserType).build().toUri());
 	}
 
-	@Test  // gh-27039
-	void expandPortAndPathWithoutSeparator() {
+	@ParameterizedTest // gh-27039
+	@EnumSource(value = ParserType.class)
+	void expandPortAndPathWithoutSeparator(ParserType parserType) {
 		URI uri = UriComponentsBuilder
-				.fromUriString("ws://localhost:{port}/{path}")
+				.fromUriString("ws://localhost:{port}/{path}", parserType)
 				.buildAndExpand(7777, "test")
 				.toUri();
 		assertThat(uri.toString()).isEqualTo("ws://localhost:7777/test");
diff --git a/spring-web/src/test/java/org/springframework/web/util/UriComponentsTests.java b/spring-web/src/test/java/org/springframework/web/util/UriComponentsTests.java
index f5003e11a5f7..f572eccbc4fd 100644
--- a/spring-web/src/test/java/org/springframework/web/util/UriComponentsTests.java
+++ b/spring-web/src/test/java/org/springframework/web/util/UriComponentsTests.java
@@ -25,6 +25,10 @@
 import java.util.Collections;
 
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.EnumSource;
+
+import org.springframework.web.util.UriComponentsBuilder.ParserType;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
@@ -74,78 +78,88 @@ void encodeAndExpandWithDollarSign() {
 		assertThat(uri.expand("JavaClass$1.class").toString()).isEqualTo("/path?q=JavaClass%241.class");
 	}
 
-	@Test
-	void toUriEncoded() {
-		UriComponents uri = UriComponentsBuilder.fromUriString("https://example.com/hotel list/Z\u00fcrich").build();
+	@ParameterizedTest
+	@EnumSource(value = ParserType.class)
+	void toUriEncoded(ParserType parserType) {
+		UriComponents uri = UriComponentsBuilder.fromUriString("https://example.com/hotel list/Z\u00fcrich", parserType).build();
 		assertThat(uri.encode().toUri()).isEqualTo(URI.create("https://example.com/hotel%20list/Z%C3%BCrich"));
 	}
 
-	@Test
-	void toUriNotEncoded() {
-		UriComponents uri = UriComponentsBuilder.fromUriString("https://example.com/hotel list/Z\u00fcrich").build();
+	@ParameterizedTest
+	@EnumSource(value = ParserType.class)
+	void toUriNotEncoded(ParserType parserType) {
+		UriComponents uri = UriComponentsBuilder.fromUriString("https://example.com/hotel list/Z\u00fcrich", parserType).build();
 		assertThat(uri.toUri()).isEqualTo(URI.create("https://example.com/hotel%20list/Z\u00fcrich"));
 	}
 
-	@Test
-	void toUriAlreadyEncoded() {
-		UriComponents uri = UriComponentsBuilder.fromUriString("https://example.com/hotel%20list/Z%C3%BCrich").build(true);
+	@ParameterizedTest
+	@EnumSource(value = ParserType.class)
+	void toUriAlreadyEncoded(ParserType parserType) {
+		UriComponents uri = UriComponentsBuilder.fromUriString("https://example.com/hotel%20list/Z%C3%BCrich", parserType).build(true);
 		assertThat(uri.encode().toUri()).isEqualTo(URI.create("https://example.com/hotel%20list/Z%C3%BCrich"));
 	}
 
-	@Test
-	void toUriWithIpv6HostAlreadyEncoded() {
+	@ParameterizedTest
+	@EnumSource(value = ParserType.class)
+	void toUriWithIpv6HostAlreadyEncoded(ParserType parserType) {
 		UriComponents uri = UriComponentsBuilder.fromUriString(
-				"http://[1abc:2abc:3abc::5ABC:6abc]:8080/hotel%20list/Z%C3%BCrich").build(true);
+				"http://[1abc:2abc:3abc::5ABC:6abc]:8080/hotel%20list/Z%C3%BCrich", parserType).build(true);
 
 		assertThat(uri.encode().toUri()).isEqualTo(
 				URI.create("http://[1abc:2abc:3abc::5ABC:6abc]:8080/hotel%20list/Z%C3%BCrich"));
 	}
 
-	@Test
-	void toUriStringWithPortVariable() {
+	@ParameterizedTest
+	@EnumSource(value = ParserType.class)
+	void toUriStringWithPortVariable(ParserType parserType) {
 		String url = "http://localhost:{port}/first";
-		assertThat(UriComponentsBuilder.fromUriString(url).build().toUriString()).isEqualTo(url);
+		assertThat(UriComponentsBuilder.fromUriString(url, parserType).build().toUriString()).isEqualTo(url);
 	}
 
-	@Test
-	void expand() {
-		UriComponents uri = UriComponentsBuilder.fromUriString("https://example.com").path("/{foo} {bar}").build();
+	@ParameterizedTest
+	@EnumSource(value = ParserType.class)
+	void expand(ParserType parserType) {
+		UriComponents uri = UriComponentsBuilder.fromUriString("https://example.com", parserType).path("/{foo} {bar}").build();
 		uri = uri.expand("1 2", "3 4");
 
 		assertThat(uri.getPath()).isEqualTo("/1 2 3 4");
 		assertThat(uri.toUriString()).isEqualTo("https://example.com/1 2 3 4");
 	}
 
-	@Test  // SPR-13311
-	void expandWithRegexVar() {
+	@ParameterizedTest // SPR-13311
+	@EnumSource(value = ParserType.class)
+	void expandWithRegexVar(ParserType parserType) {
 		String template = "/myurl/{name:[a-z]{1,5}}/show";
-		UriComponents uri = UriComponentsBuilder.fromUriString(template).build();
+		UriComponents uri = UriComponentsBuilder.fromUriString(template, parserType).build();
 		uri = uri.expand(Collections.singletonMap("name", "test"));
 
 		assertThat(uri.getPath()).isEqualTo("/myurl/test/show");
 	}
 
-	@Test  // SPR-17630
-	void uirTemplateExpandWithMismatchedCurlyBraces() {
-		UriComponents uri = UriComponentsBuilder.fromUriString("/myurl/?q={{{{").encode().build();
+	@ParameterizedTest // SPR-17630
+	@EnumSource(value = ParserType.class)
+	void uirTemplateExpandWithMismatchedCurlyBraces(ParserType parserType) {
+		UriComponents uri = UriComponentsBuilder.fromUriString("/myurl/?q={{{{", parserType).encode().build();
 		assertThat(uri.toUriString()).isEqualTo("/myurl/?q=%7B%7B%7B%7B");
 	}
 
-	@Test  // gh-22447
-	void expandWithFragmentOrder() {
+	@ParameterizedTest // gh-22447
+	@EnumSource(value = ParserType.class)
+	void expandWithFragmentOrder(ParserType parserType) {
 		UriComponents uri = UriComponentsBuilder
-				.fromUriString("https://{host}/{path}#{fragment}").build()
+				.fromUriString("https://{host}/{path}#{fragment}", parserType).build()
 				.expand("example.com", "foo", "bar");
 
 		assertThat(uri.toUriString()).isEqualTo("https://example.com/foo#bar");
 	}
 
-	@Test  // SPR-12123
-	void port() {
-		UriComponents uri1 = fromUriString("https://example.com:8080/bar").build();
-		UriComponents uri2 = fromUriString("https://example.com/bar").port(8080).build();
-		UriComponents uri3 = fromUriString("https://example.com/bar").port("{port}").build().expand(8080);
-		UriComponents uri4 = fromUriString("https://example.com/bar").port("808{digit}").build().expand(0);
+	@ParameterizedTest // SPR-12123
+	@EnumSource(value = ParserType.class)
+	void port(ParserType parserType) {
+		UriComponents uri1 = fromUriString("https://example.com:8080/bar", parserType).build();
+		UriComponents uri2 = fromUriString("https://example.com/bar", parserType).port(8080).build();
+		UriComponents uri3 = fromUriString("https://example.com/bar", parserType).port("{port}").build().expand(8080);
+		UriComponents uri4 = fromUriString("https://example.com/bar", parserType).port("808{digit}").build().expand(0);
 
 		assertThat(uri1.getPort()).isEqualTo(8080);
 		assertThat(uri1.toUriString()).isEqualTo("https://example.com:8080/bar");
@@ -157,11 +171,12 @@ void port() {
 		assertThat(uri4.toUriString()).isEqualTo("https://example.com:8080/bar");
 	}
 
-	@Test  // gh-28521
-	void invalidPort() {
+	@ParameterizedTest // gh-28521
+	@EnumSource(value = ParserType.class)
+	void invalidPort(ParserType parserType) {
 		assertThatExceptionOfType(InvalidUrlException.class)
-				.isThrownBy(() -> fromUriString("https://example.com:XXX/bar"));
-		assertExceptionsForInvalidPort(fromUriString("https://example.com/bar").port("XXX").build());
+				.isThrownBy(() -> fromUriString("https://example.com:XXX/bar", parserType));
+		assertExceptionsForInvalidPort(fromUriString("https://example.com/bar", parserType).port("XXX").build());
 	}
 
 	private void assertExceptionsForInvalidPort(UriComponents uriComponents) {
@@ -191,16 +206,18 @@ void invalidEncodedSequence() {
 				UriComponentsBuilder.fromPath("/fo%2o").build(true));
 	}
 
-	@Test
-	void normalize() {
-		UriComponents uri = UriComponentsBuilder.fromUriString("https://example.com/foo/../bar").build();
+	@ParameterizedTest
+	@EnumSource(value = ParserType.class)
+	void normalize(ParserType parserType) {
+		UriComponents uri = UriComponentsBuilder.fromUriString("https://example.com/foo/../bar", parserType).build();
 		assertThat(uri.normalize().toString()).isEqualTo("https://example.com/bar");
 	}
 
-	@Test
-	void serializable() throws Exception {
+	@ParameterizedTest
+	@EnumSource(value = ParserType.class)
+	void serializable(ParserType parserType) throws Exception {
 		UriComponents uri = UriComponentsBuilder.fromUriString(
-				"https://example.com").path("/{foo}").query("bar={baz}").build();
+				"https://example.com", parserType).path("/{foo}").query("bar={baz}").build();
 
 		ByteArrayOutputStream bos = new ByteArrayOutputStream();
 		ObjectOutputStream oos = new ObjectOutputStream(bos);
@@ -222,12 +239,13 @@ void copyToUriComponentsBuilder() {
 		assertThat(result.getPathSegments()).isEqualTo(Arrays.asList("foo", "bar", "ba%2Fz"));
 	}
 
-	@Test
-	void equalsHierarchicalUriComponents() {
+	@ParameterizedTest
+	@EnumSource(value = ParserType.class)
+	void equalsHierarchicalUriComponents(ParserType parserType) {
 		String url = "https://example.com";
-		UriComponents uric1 = UriComponentsBuilder.fromUriString(url).path("/{foo}").query("bar={baz}").build();
-		UriComponents uric2 = UriComponentsBuilder.fromUriString(url).path("/{foo}").query("bar={baz}").build();
-		UriComponents uric3 = UriComponentsBuilder.fromUriString(url).path("/{foo}").query("bin={baz}").build();
+		UriComponents uric1 = UriComponentsBuilder.fromUriString(url, parserType).path("/{foo}").query("bar={baz}").build();
+		UriComponents uric2 = UriComponentsBuilder.fromUriString(url, parserType).path("/{foo}").query("bar={baz}").build();
+		UriComponents uric3 = UriComponentsBuilder.fromUriString(url, parserType).path("/{foo}").query("bin={baz}").build();
 
 		assertThat(uric1).isInstanceOf(HierarchicalUriComponents.class);
 		assertThat(uric1).isEqualTo(uric1);
@@ -235,12 +253,13 @@ void equalsHierarchicalUriComponents() {
 		assertThat(uric1).isNotEqualTo(uric3);
 	}
 
-	@Test
-	void equalsOpaqueUriComponents() {
+	@ParameterizedTest
+	@EnumSource(value = ParserType.class)
+	void equalsOpaqueUriComponents(ParserType parserType) {
 		String baseUrl = "http:example.com";
-		UriComponents uric1 = UriComponentsBuilder.fromUriString(baseUrl + "/foo/bar").build();
-		UriComponents uric2 = UriComponentsBuilder.fromUriString(baseUrl + "/foo/bar").build();
-		UriComponents uric3 = UriComponentsBuilder.fromUriString(baseUrl + "/foo/bin").build();
+		UriComponents uric1 = UriComponentsBuilder.fromUriString(baseUrl + "/foo/bar", parserType).build();
+		UriComponents uric2 = UriComponentsBuilder.fromUriString(baseUrl + "/foo/bar", parserType).build();
+		UriComponents uric3 = UriComponentsBuilder.fromUriString(baseUrl + "/foo/bin", parserType).build();
 
 		assertThat(uric1).isEqualTo(uric1);
 		assertThat(uric1).isEqualTo(uric2);