diff --git a/LocalSettings.txt b/LocalSettings.txt
index 20b58c5c..d3fb7cad 100644
--- a/LocalSettings.txt
+++ b/LocalSettings.txt
@@ -63,3 +63,16 @@ $wgGENewcomerTasksRemoteApiUrl = 'https://en.wikipedia.org/w/api.php';
 $wgGENewcomerTasksTopicType = 'ores';
 $wgWelcomeSurveyExperimentalGroups['exp2_target_specialpage']['range'] = '0-9';
 $wgGEHomepageMentorsList = 'Project:GrowthExperiments_mentors';
+
+// Apply config.json
+$config = json_decode(
+	file_get_contents( 'config.json' ),
+	true
+);
+if ( $config ) {
+	foreach ( $config as $key => $value ) {
+		$name = "wg$key";
+		$$name = $value;
+	}
+}
+
diff --git a/createwiki.sh b/createwiki.sh
index 8c9b7127..3c10a215 100755
--- a/createwiki.sh
+++ b/createwiki.sh
@@ -49,6 +49,9 @@ date +%s > $PATCHDEMO/wikis/$NAME/created.txt
 # apply our default settings
 cat $PATCHDEMO/LocalSettings.txt >> $PATCHDEMO/wikis/$NAME/w/LocalSettings.php
 
+# add site config
+echo "$SITECONFIG" >> $PATCHDEMO/wikis/$NAME/w/config.json
+
 # update Main_Page
 sleep 1 # Ensure edit appears after creation in history
 echo "$MAINPAGE" | php $PATCHDEMO/wikis/$NAME/w/maintenance/edit.php "Main_Page"
diff --git a/index.js b/index.js
index c368fc47..4b4dc199 100644
--- a/index.js
+++ b/index.js
@@ -2,7 +2,8 @@
 	// TODO: Use infuse to control OOUI widgets
 	var myWikis, wikisTable, branchSelect,
 		form = document.getElementById( 'new-form' ),
-		submit = form.querySelector( 'button[type=submit]' );
+		submit = form.querySelector( 'button[type=submit]' ),
+		siteConfig = form.querySelector( '[name=siteConfig]' );
 
 	function setDisabled( input, disabled ) {
 		input.disabled = disabled;
@@ -10,7 +11,17 @@
 		input.parentNode.classList.toggle( 'oo-ui-widget-enabled', !disabled );
 	}
 
-	form.addEventListener( 'submit', function () {
+	form.addEventListener( 'submit', function ( e ) {
+		if ( siteConfig.value.trim() ) {
+			try {
+				JSON.parse( siteConfig.value );
+			} catch ( err ) {
+				e.preventDefault();
+				// eslint-disable-next-line no-alert
+				alert( 'Invalid JSON: ' + err.message );
+				return;
+			}
+		}
 		setDisabled( submit, true );
 		return false;
 	} );
diff --git a/index.php b/index.php
index af3642a5..1f3bf169 100644
--- a/index.php
+++ b/index.php
@@ -68,6 +68,19 @@
 						'align' => 'left',
 					]
 				),
+				new OOUI\FieldLayout(
+					new OOUI\MultilineTextInputWidget( [
+						'name' => 'siteConfig',
+						'placeholder' => "{\n    \"Sitename\": \"Test wiki\"\n}",
+						'rows' => 4,
+					] ),
+					[
+						'label' => 'Site config:',
+						'help' => new OOUI\HtmlSnippet( 'All keys will be given a <strong><code>$wg</code></strong> prefix.<br/>This file will be <strong>public</strong>.' ),
+						'helpInline' => true,
+						'align' => 'left',
+					]
+				),
 				new DetailsFieldLayout(
 					new OOUI\CheckboxMultiselectInputWidget( [
 						'name' => 'repos[]',
@@ -75,7 +88,9 @@
 						'value' => array_keys( $repoData ),
 					] ),
 					[
-						'label' => 'Choose extensions to enable (default: all):',
+						'label' => 'Choose extensions to enable:',
+						'help' => new OOUI\HtmlSnippet( '<br/>Defaults to all' ),
+						'helpInline' => true,
 						'align' => 'left',
 					]
 				),
@@ -157,6 +172,8 @@
 				}
 				$creator = get_creator( $dir );
 				$created = get_created( $dir );
+				$siteConfig = get_if_file_exists( 'wikis/' . $dir . '/w/config.json' );
+				$hasConfig = $siteConfig && strlen( trim( $siteConfig ) );
 
 				if ( !$created ) {
 					// Add created.txt to old wikis
@@ -169,7 +186,8 @@
 				$wikis[ $dir ] = [
 					'mtime' => $created,
 					'title' => $title,
-					'creator' => $creator
+					'creator' => $creator,
+					'hasConfig' => $hasConfig,
 				];
 			}
 		}
@@ -190,7 +208,13 @@
 		$anyCanDelete = $anyCanDelete || $canDelete;
 		$rows .= '<tr' . ( $creator !== $username ? ' class="other"' : '' ) . '>' .
 			'<td class="title">' . ( $title ?: '<em>No patches</em>' ) . '</td>' .
-			'<td><a href="wikis/' . $wiki . '/w">' . $wiki . '</a></td>' .
+			'<td>' .
+				( !empty( $data[ 'hasConfig' ] ) ?
+					'<a href="wikis/' . $wiki . '/w/config.json">JSON</a>' :
+					''
+				) .
+			'</td>' .
+			'<td><a href="wikis/' . $wiki . '/w">' . substr( $wiki, 0, 20 ) . '&hellip;</a></td>' .
 			'<td class="date">' . date( 'c', $data[ 'mtime' ] ) . '</td>' .
 			( $useOAuth ? '<td>' . ( $creator ? user_link( $creator ) : '?' ) . '</td>' : '' ) .
 			( $canDelete ?
@@ -202,6 +226,7 @@
 
 	echo '<tr>' .
 			'<th>Patches</th>' .
+			'<th>Config</th>' .
 			'<th>Link</th>' .
 			'<th>Time</th>' .
 			( $useOAuth ? '<th>Creator</th>' : '' ) .
diff --git a/new.php b/new.php
index 61825a01..593f3938 100644
--- a/new.php
+++ b/new.php
@@ -6,6 +6,7 @@
 
 $branch = trim( $_POST['branch'] );
 $patches = trim( $_POST['patches'] );
+$siteConfig = trim( $_POST['siteConfig'] );
 
 $namePath = md5( $branch . $patches . time() );
 $server = ( isset( $_SERVER['HTTPS'] ) ? 'https://' : 'http://' ) . $_SERVER['HTTP_HOST'];
@@ -180,6 +181,7 @@
 	'WIKINAME' => $wikiName,
 	'CREATOR' => $user ? $user->username : '',
 	'MAINPAGE' => $mainPage,
+	'SITECONFIG' => $siteConfig,
 	'SERVER' => $server,
 	'SERVERPATH' => $serverPath,
 	'COMPOSER_HOME' => __DIR__ . '/composer',