diff --git a/pom.xml b/pom.xml
index 4a2684a..31e5bb9 100644
--- a/pom.xml
+++ b/pom.xml
@@ -6,7 +6,7 @@
 
     <groupId>com.danielflower.apprunner</groupId>
     <artifactId>restabuild</artifactId>
-    <version>1.1-SNAPSHOT</version>
+    <version>1.2-SNAPSHOT</version>
 
     <name>Restabuild</name>
     <description>Builds Git-hosted projects via a REST API</description>
@@ -58,7 +58,7 @@
         <dependency>
             <groupId>ch.qos.logback</groupId>
             <artifactId>logback-classic</artifactId>
-            <version>1.5.2</version>
+            <version>1.5.6</version>
             <scope>runtime</scope>
         </dependency>
         <dependency>
@@ -86,7 +86,7 @@
         <dependency>
             <groupId>io.muserver</groupId>
             <artifactId>mu-server</artifactId>
-            <version>2.0.0</version>
+            <version>2.0.1</version>
         </dependency>
 
         <!-- git stuff -->
@@ -203,7 +203,7 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-shade-plugin</artifactId>
-                <version>3.5.3</version>
+                <version>3.6.0</version>
                 <executions>
                     <execution>
                         <phase>package</phase>
@@ -236,7 +236,7 @@
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-javadoc-plugin</artifactId>
-                <version>3.6.3</version>
+                <version>3.7.0</version>
                 <executions>
                     <execution>
                         <id>attach-javadocs</id>
diff --git a/sample-config.properties b/sample-config.properties
index 65529ec..89049a3 100644
--- a/sample-config.properties
+++ b/sample-config.properties
@@ -14,5 +14,14 @@ restabuild.context=/restabuild
 # The timeout threshold per run (unit in minute)
 restabuild.timeout=30
 
-# Controls whether or not to delete the instance directories of each build upon completion. Valid values: ALWAYS, NEVER, ON_SUCCESS
-restabuild.delete.policy=ON_SUCCESS
\ No newline at end of file
+# Controls whether to delete the instance directories of each build upon completion. Valid values: ALWAYS, NEVER, ON_SUCCESS
+restabuild.delete.policy=ON_SUCCESS
+
+# An optional regular expression pattern that git URLs must match. Empty to allow any URLs.
+restabuild.git.url.pattern=https://github\.com/.*\.git
+
+# The message to return to users if the git URL specified does not match the allowed regular expression
+restabuild.git.url.validation.message=Only HTTPS github.com URLs are allowed
+
+# The example URL to show in the UI
+restabuild.example.url=https://github.com/3redronin/mu-server-sample.git
\ No newline at end of file
diff --git a/src/main/java/com/danielflower/restabuild/App.java b/src/main/java/com/danielflower/restabuild/App.java
index 025a284..30e571a 100644
--- a/src/main/java/com/danielflower/restabuild/App.java
+++ b/src/main/java/com/danielflower/restabuild/App.java
@@ -48,9 +48,9 @@ public void start() throws IOException {
 
         buildQueue = new BuildQueue(numberOfConcurrentBuilds, buildTimeoutMinutes, config.deletePolicy());
 
-        BuildResource buildResource = new BuildResource(fileSandbox, database, buildQueue, executorService);
+        BuildResource buildResource = new BuildResource(fileSandbox, database, buildQueue, executorService, config.allowedRepoUrlPattern(), config.allowedRepoUrlValidationMessage());
         String context = Mutils.trim(config.get(Config.CONTEXT, "restabuild"), "/");
-        webServer = WebServer.start(appRunnerPort, context, buildResource, buildTimeoutMinutes);
+        webServer = WebServer.start(appRunnerPort, context, buildResource, buildTimeoutMinutes, config);
     }
 
     private void deleteOldTempFiles(File tempDir) {
diff --git a/src/main/java/com/danielflower/restabuild/Config.java b/src/main/java/com/danielflower/restabuild/Config.java
index 9d3ee71..b5eed23 100644
--- a/src/main/java/com/danielflower/restabuild/Config.java
+++ b/src/main/java/com/danielflower/restabuild/Config.java
@@ -1,8 +1,8 @@
 package com.danielflower.restabuild;
 
 import com.danielflower.restabuild.build.DeletePolicy;
-import com.danielflower.restabuild.build.RestaBuildException;
 import com.danielflower.restabuild.build.InvalidConfigException;
+import com.danielflower.restabuild.build.RestaBuildException;
 import org.apache.commons.io.FileUtils;
 
 import java.io.File;
@@ -11,6 +11,7 @@
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Properties;
+import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
@@ -90,6 +91,19 @@ public int getInt(String name, int defaultValue) {
         }
     }
 
+    public Pattern allowedRepoUrlPattern() {
+        String exp = get("restabuild.git.url.pattern", ".*");
+        return Pattern.compile(exp);
+    }
+
+    public String allowedRepoUrlValidationMessage() {
+        return get("restabuild.git.url.validation.message", "Sorry, that URL is not allowed.");
+    }
+
+    public String exampleURl() {
+        return get("restabuild.example.url", "");
+    }
+
 
     public File getOrCreateDir(String name) {
         File f = new File(get(name));
@@ -105,5 +119,11 @@ public static boolean isWindows() {
         return File.separatorChar == '\\';
     }
 
+    public Config clone(String keyToChange, String valueForKey) {
+        Map<String, String> copy = new HashMap<>(raw);
+        copy.put(keyToChange, valueForKey);
+        return new Config(copy);
+    }
+
 }
 
diff --git a/src/main/java/com/danielflower/restabuild/web/BuildResource.java b/src/main/java/com/danielflower/restabuild/web/BuildResource.java
index fbbec89..a4e9e5a 100644
--- a/src/main/java/com/danielflower/restabuild/web/BuildResource.java
+++ b/src/main/java/com/danielflower/restabuild/web/BuildResource.java
@@ -26,6 +26,7 @@
 import java.util.Optional;
 import java.util.UUID;
 import java.util.concurrent.ExecutorService;
+import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 
 @Path("api/v1/builds")
@@ -42,12 +43,16 @@ public class BuildResource {
     private final BuildDatabase database;
     private final BuildQueue buildQueue;
     private final ExecutorService executorService;
+    private final Pattern allowedUrlPattern;
+    private final String urlPatternValidationErrorMessage;
 
-    public BuildResource(FileSandbox fileSandbox, BuildDatabase database, BuildQueue buildQueue, ExecutorService executorService) {
+    public BuildResource(FileSandbox fileSandbox, BuildDatabase database, BuildQueue buildQueue, ExecutorService executorService, Pattern allowedUrlPattern, String urlPatternValidationErrorMessage) {
         this.fileSandbox = fileSandbox;
         this.buildQueue = buildQueue;
         this.database = database;
         this.executorService = executorService;
+        this.allowedUrlPattern = allowedUrlPattern;
+        this.urlPatternValidationErrorMessage = urlPatternValidationErrorMessage;
     }
 
     @POST
@@ -104,6 +109,10 @@ private URIish validateGitUrl(String gitUrl) {
         } catch (URISyntaxException e) {
             throw new BadRequestException("An invalid Git URL was specified: " + e.getMessage());
         }
+        if (!allowedUrlPattern.matcher(gitUrl).matches()) {
+            System.out.println("gitUrl = " + gitUrl);
+            throw new BadRequestException(urlPatternValidationErrorMessage);
+        }
         return gitURIish;
     }
 
diff --git a/src/main/java/com/danielflower/restabuild/web/IndexHtmlHandler.java b/src/main/java/com/danielflower/restabuild/web/IndexHtmlHandler.java
index ead9495..2dbcbd4 100644
--- a/src/main/java/com/danielflower/restabuild/web/IndexHtmlHandler.java
+++ b/src/main/java/com/danielflower/restabuild/web/IndexHtmlHandler.java
@@ -1,10 +1,12 @@
 package com.danielflower.restabuild.web;
 
+import com.danielflower.restabuild.Config;
 import com.danielflower.restabuild.build.BuildResult;
-import com.danielflower.restabuild.build.RemoteGitRepo;
 import io.muserver.*;
 
 import java.io.IOException;
+import java.io.InputStream;
+import java.nio.charset.StandardCharsets;
 import java.util.Map;
 
 import static io.muserver.Mutils.coalesce;
@@ -13,17 +15,30 @@ public class IndexHtmlHandler implements RouteHandler {
 
     private final String template;
 
-    public IndexHtmlHandler() throws IOException {
+    public IndexHtmlHandler(Config config) throws IOException {
 
         String version = coalesce(getClass().getPackage().getImplementationVersion(), "dev");
 
-        template = new String(Mutils.toByteArray(IndexHtmlHandler.class.getResourceAsStream("/web/index.html"), 8192), "UTF-8")
+        StringBuilder inputBoxAttributes = new StringBuilder();
+        String urlPattern = config.allowedRepoUrlPattern().pattern();
+        if (!urlPattern.equals(".*")) {
+            inputBoxAttributes.append(" pattern=\"").append(Mutils.htmlEncode(urlPattern)).append("\" title=\"").append(Mutils.htmlEncode(config.allowedRepoUrlValidationMessage())).append("\"");
+        }
+        if (!Mutils.nullOrEmpty(config.exampleURl())) {
+            inputBoxAttributes.append(" placeholder=\"").append(Mutils.htmlEncode(config.exampleURl())).append("\"");
+        }
+
+        InputStream template = IndexHtmlHandler.class.getResourceAsStream("/web/index.html");
+        this.template = new String(Mutils.toByteArray(template, 8192), StandardCharsets.UTF_8)
             .replace("{{buildfilename}}", BuildResult.buildFile)
-            .replace("{{restabuildversion}}", version);
+            .replace("{{restabuildversion}}", version)
+            .replace("{{gitUrlTextBoxAttributes}}", inputBoxAttributes.toString())
+
+        ;
     }
 
     @Override
-    public void handle(MuRequest request, MuResponse response, Map<String, String> pathParams) throws Exception {
+    public void handle(MuRequest request, MuResponse response, Map<String, String> pathParams) {
         response.contentType(ContentTypes.TEXT_HTML_UTF8);
         response.write(template);
     }
diff --git a/src/main/java/com/danielflower/restabuild/web/WebServer.java b/src/main/java/com/danielflower/restabuild/web/WebServer.java
index ff0c7dc..c7f6043 100644
--- a/src/main/java/com/danielflower/restabuild/web/WebServer.java
+++ b/src/main/java/com/danielflower/restabuild/web/WebServer.java
@@ -1,5 +1,6 @@
 package com.danielflower.restabuild.web;
 
+import com.danielflower.restabuild.Config;
 import io.muserver.Method;
 import io.muserver.MuServer;
 import io.muserver.Mutils;
@@ -25,7 +26,7 @@ private WebServer(MuServer server) {
         this.server = server;
     }
 
-    public static WebServer start(int port, String context, BuildResource buildResource, int buildTimeoutMinutes) throws IOException {
+    public static WebServer start(int port, String context, BuildResource buildResource, int buildTimeoutMinutes, Config config) throws IOException {
         boolean hasContext = !Mutils.nullOrEmpty(context);
         MuServer server = muServer()
             .withHttpPort(port)
@@ -55,7 +56,7 @@ public static WebServer start(int port, String context, BuildResource buildResou
                                 .build())
                         )
                     )
-                    .addHandler(Method.GET, "/", new IndexHtmlHandler())
+                    .addHandler(Method.GET, "/", new IndexHtmlHandler(config))
                     .addHandler(fileOrClasspath("src/main/resources/web", "/web")))
             .start();
 
diff --git a/src/main/resources/web/index.html b/src/main/resources/web/index.html
index 8da9e9c..06c169c 100644
--- a/src/main/resources/web/index.html
+++ b/src/main/resources/web/index.html
@@ -49,8 +49,7 @@ <h2>Submit a build</h2>
 <form id="createForm" action="api/v1/builds" method="post">
     <label>
         Git URL:
-        <input type="text" id="gitUrlBox" name="gitUrl" required
-               placeholder="https://github.com/3redronin/mu-server-sample.git">
+        <input type="text" id="gitUrlBox" name="gitUrl" required {{gitUrlTextBoxAttributes}}>
     </label>
     <label>
         Git Branch:
diff --git a/src/test/java/com/danielflower/restabuild/SystemTest.java b/src/test/java/com/danielflower/restabuild/SystemTest.java
index 9af3daa..148b591 100644
--- a/src/test/java/com/danielflower/restabuild/SystemTest.java
+++ b/src/test/java/com/danielflower/restabuild/SystemTest.java
@@ -31,7 +31,8 @@ public class SystemTest {
 
     @BeforeClass
     public static void start() throws Exception {
-        config = Config.load(new String[]{"sample-config.properties"});
+        config = Config.load(new String[]{"sample-config.properties"})
+            .clone("restabuild.git.url.pattern", "file:/.*");
         app = new App(config);
         app.start();
     }
@@ -70,6 +71,17 @@ public void theRestApiCanBeUsedToBuildStuff() throws Exception {
         assertThat(afterBuild.getJSONArray("tagsCreated").get(0), is("my-maven-app-1.0.0"));
     }
 
+    @Test
+    public void ifTheGitUrlDoesNotMatchThePatternYouGetA400() throws Exception {
+        Fields fields = new Fields();
+        // this test class changes the sample-config.properties file to be file:/ URLs only, so not quite testing the sample-config properties value here
+        fields.add("gitUrl", "ssh://github.com/blah.git");
+        ContentResponse resp = client.FORM(buildsUrl(), fields);
+        assertThat(resp.getStatus(), equalTo(400));
+        // the message is set in sample-config.properties
+        assertThat(resp.getContentAsString(), containsString("Only HTTPS github.com URLs are allowed"));
+    }
+
     private JSONObject waitForBuildToFinish(JSONObject build, BuildStatus expectedStatus) throws InterruptedException, ExecutionException, TimeoutException {
         String url = build.getString("url");