diff --git a/builder/src/main/java/net/kemitix/checkstyle/ruleset/builder/CheckstyleWriter.java b/builder/src/main/java/net/kemitix/checkstyle/ruleset/builder/CheckstyleWriter.java
new file mode 100644
index 0000000..985fb2f
--- /dev/null
+++ b/builder/src/main/java/net/kemitix/checkstyle/ruleset/builder/CheckstyleWriter.java
@@ -0,0 +1,112 @@
+/*
+The MIT License (MIT)
+
+Copyright (c) 2016 Paul Campbell
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+*/
+
+package net.kemitix.checkstyle.ruleset.builder;
+
+import com.speedment.common.mapstream.MapStream;
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
+import lombok.val;
+import org.springframework.boot.CommandLineRunner;
+import org.springframework.stereotype.Component;
+
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.StandardOpenOption;
+import java.util.Arrays;
+import java.util.Map;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+/**
+ * Writes the Checkstyle XML files.
+ *
+ * @author Paul Campbell (pcampbell@kemitix.net)
+ */
+@Component
+@RequiredArgsConstructor
+class CheckstyleWriter implements CommandLineRunner {
+
+    private final OutputProperties outputProperties;
+
+    private final RulesProperties rulesProperties;
+
+    @Override
+    public void run(final String... args) throws Exception {
+        Stream.of(RuleLevel.values())
+              .forEach(this::writeCheckstyleFile);
+    }
+
+    private void writeCheckstyleFile(@NonNull final RuleLevel ruleLevel) {
+        val xmlFile = outputProperties.getDirectory()
+                                      .resolve(outputProperties.getRulesetFiles()
+                                                               .get(ruleLevel));
+        val checkerRules = rulesProperties.getRules()
+                                          .stream()
+                                          .filter(Rule::isEnabled)
+                                          .filter(rule -> RuleParent.CHECKER.equals(rule.getParent()))
+                                          .filter(rule -> ruleLevel.compareTo(rule.getLevel()) >= 0)
+                                          .map(this::formatRuleAsModule)
+                                          .collect(Collectors.joining("\n"));
+        val treeWalkerRules = rulesProperties.getRules()
+                                             .stream()
+                                             .filter(Rule::isEnabled)
+                                             .filter(rule -> RuleParent.TREEWALKER.equals(rule.getParent()))
+                                             .filter(rule -> ruleLevel.compareTo(rule.getLevel()) >= 0)
+                                             .map(this::formatRuleAsModule)
+                                             .collect(Collectors.joining("\n"));
+
+
+        try {
+            val checkstyleXmlTemplate = outputProperties.getCheckstyleXmlTemplate();
+            if (!checkstyleXmlTemplate.toFile()
+                                      .exists()) {
+                throw new IOException(checkstyleXmlTemplate.toString());
+            }
+            val bytes = Files.readAllBytes(checkstyleXmlTemplate);
+            val template = new String(bytes);
+            val output = Arrays.asList(String.format(template, checkerRules, treeWalkerRules)
+                                             .split("\n"));
+            Files.write(xmlFile, output, StandardCharsets.UTF_8, StandardOpenOption.TRUNCATE_EXISTING);
+        } catch (IOException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    private String formatRuleAsModule(final Rule rule) {
+        if (rule.getProperties()
+                .isEmpty()) {
+            return String.format("<module name=\"%s\"/>", rule.getName());
+        }
+        return String.format("<module name=\"%s\">%n    %s%n</module>", rule.getName(),
+                             formatProperties(rule.getProperties()));
+    }
+
+    private String formatProperties(final Map<String, String> properties) {
+        return MapStream.of(properties)
+                        .map((k, v) -> String.format("<property name=\"%s\" value=\"%s\"/>", k, v))
+                        .collect(Collectors.joining("\n"));
+    }
+}