diff --git a/json-compatibility-suite/pom.xml b/json-compatibility-suite/pom.xml
new file mode 100644
index 0000000..f1fb066
--- /dev/null
+++ b/json-compatibility-suite/pom.xml
@@ -0,0 +1,65 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>io.github.simbo1905.json</groupId>
+        <artifactId>json-java21-parent</artifactId>
+        <version>0.1-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>json-compatibility-suite</artifactId>
+    <packaging>jar</packaging>
+
+    <name>JSON Compatibility Suite</name>
+
+    <dependencies>
+        <dependency>
+            <groupId>io.github.simbo1905.json</groupId>
+            <artifactId>json-java21</artifactId>
+            <version>${project.version}</version>
+        </dependency>
+        <!-- JUnit 5 for testing -->
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>com.googlecode.maven-download-plugin</groupId>
+                <artifactId>download-maven-plugin</artifactId>
+                <executions>
+                    <execution>
+                        <id>download-json-test-suite</id>
+                        <phase>generate-test-resources</phase>
+                        <goals>
+                            <goal>wget</goal>
+                        </goals>
+                        <configuration>
+                            <url>https://github.com/nst/JSONTestSuite/archive/refs/heads/master.zip</url>
+                            <outputDirectory>${project.build.directory}/test-resources</outputDirectory>
+                            <outputFileName>json-test-suite.zip</outputFileName>
+                            <unpack>true</unpack>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+</project>
diff --git a/json-compatibility-suite/src/test/java/jdk/sandbox/compatibility/DownloadVerificationTest.java b/json-compatibility-suite/src/test/java/jdk/sandbox/compatibility/DownloadVerificationTest.java
new file mode 100644
index 0000000..2a9a176
--- /dev/null
+++ b/json-compatibility-suite/src/test/java/jdk/sandbox/compatibility/DownloadVerificationTest.java
@@ -0,0 +1,23 @@
+package jdk.sandbox.compatibility;
+
+import org.junit.jupiter.api.Test;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class DownloadVerificationTest {
+    @Test
+    void testSuiteDownloaded() {
+        Path testDir = Paths.get("target/test-resources/JSONTestSuite-master/test_parsing");
+        assertThat(testDir)
+            .as("JSON Test Suite should be downloaded and extracted")
+            .exists()
+            .isDirectory();
+        
+        // Verify some test files exist
+        assertThat(testDir.resolve("y_structure_whitespace_array.json"))
+            .as("Should contain valid test files")
+            .exists();
+    }
+}
diff --git a/json-compatibility-suite/src/test/java/jdk/sandbox/compatibility/JsonTestSuiteTest.java b/json-compatibility-suite/src/test/java/jdk/sandbox/compatibility/JsonTestSuiteTest.java
new file mode 100644
index 0000000..c4878f1
--- /dev/null
+++ b/json-compatibility-suite/src/test/java/jdk/sandbox/compatibility/JsonTestSuiteTest.java
@@ -0,0 +1,71 @@
+package jdk.sandbox.compatibility;
+
+import jdk.sandbox.java.util.json.Json;
+import jdk.sandbox.java.util.json.JsonParseException;
+import org.junit.jupiter.api.DynamicTest;
+import org.junit.jupiter.api.TestFactory;
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.stream.Stream;
+
+import static org.assertj.core.api.Assertions.*;
+
+/**
+ * Runs the JSON Test Suite against our implementation.
+ * Files are categorized:
+ * - y_*.json: Valid JSON that MUST parse successfully
+ * - n_*.json: Invalid JSON that MUST fail to parse
+ * - i_*.json: Implementation-defined (may accept or reject)
+ */
+public class JsonTestSuiteTest {
+
+    private static final Path TEST_DIR = Paths.get("target/test-resources/JSONTestSuite-master/test_parsing");
+
+    @TestFactory
+    Stream<DynamicTest> runJsonTestSuite() throws Exception {
+        if (!Files.exists(TEST_DIR)) {
+            System.err.println("Test suite not found. Run: mvn test-compile");
+            return Stream.empty();
+        }
+
+        return Files.walk(TEST_DIR)
+            .filter(p -> p.toString().endsWith(".json"))
+            .sorted()
+            .map(this::createTest);
+    }
+
+    private DynamicTest createTest(Path file) {
+        String filename = file.getFileName().toString();
+        
+        return DynamicTest.dynamicTest(filename, () -> {
+            String content = Files.readString(file);
+            
+            if (filename.startsWith("y_")) {
+                // Valid JSON - must parse successfully
+                assertThatCode(() -> Json.parse(content))
+                    .as("File %s should parse successfully", filename)
+                    .doesNotThrowAnyException();
+                    
+            } else if (filename.startsWith("n_")) {
+                // Invalid JSON - must fail to parse
+                assertThatThrownBy(() -> Json.parse(content))
+                    .as("File %s should fail to parse", filename)
+                    .isInstanceOf(JsonParseException.class);
+                    
+            } else if (filename.startsWith("i_")) {
+                // Implementation defined - just verify no crash
+                try {
+                    Json.parse(content);
+                    // OK - we accepted it
+                } catch (JsonParseException e) {
+                    // OK - we rejected it
+                } catch (Exception e) {
+                    // NOT OK - unexpected exception type
+                    fail("Unexpected exception for %s: %s", filename, e);
+                }
+            }
+        });
+    }
+}
diff --git a/pom.xml b/pom.xml
index 4909985..81afde2 100644
--- a/pom.xml
+++ b/pom.xml
@@ -38,6 +38,7 @@
     <modules>
         <module>json-java21</module>
         <module>json-java21-api-tracker</module>
+        <module>json-compatibility-suite</module>
     </modules>
 
     <properties>
@@ -53,6 +54,7 @@
         <maven-surefire-plugin.version>3.2.5</maven-surefire-plugin.version>
         <maven-jar-plugin.version>3.4.2</maven-jar-plugin.version>
         <maven-install-plugin.version>3.1.2</maven-install-plugin.version>
+        <download-maven-plugin.version>1.7.1</download-maven-plugin.version>
     </properties>
 
     
@@ -113,7 +115,12 @@
                     <artifactId>maven-install-plugin</artifactId>
                     <version>${maven-install-plugin.version}</version>
                 </plugin>
+                <plugin>
+                    <groupId>com.googlecode.maven-download-plugin</groupId>
+                    <artifactId>download-maven-plugin</artifactId>
+                    <version>${download-maven-plugin.version}</version>
+                </plugin>
             </plugins>
         </pluginManagement>
     </build>
-</project>
\ No newline at end of file
+</project>