diff --git a/src/applications/conduit/parametertype/ConduitBoolParameterType.php b/src/applications/conduit/parametertype/ConduitBoolParameterType.php
--- a/src/applications/conduit/parametertype/ConduitBoolParameterType.php
+++ b/src/applications/conduit/parametertype/ConduitBoolParameterType.php
@@ -5,15 +5,7 @@
 
   protected function getParameterValue(array $request, $key) {
     $value = parent::getParameterValue($request, $key);
-
-    if (!is_bool($value)) {
-      $this->raiseValidationException(
-        $request,
-        $key,
-        pht('Expected boolean (true or false), got something else.'));
-    }
-
-    return $value;
+    return $this->parseBoolValue($request, $key, $value);
   }
 
   protected function getParameterTypeName() {
diff --git a/src/applications/conduit/parametertype/ConduitEpochParameterType.php b/src/applications/conduit/parametertype/ConduitEpochParameterType.php
--- a/src/applications/conduit/parametertype/ConduitEpochParameterType.php
+++ b/src/applications/conduit/parametertype/ConduitEpochParameterType.php
@@ -5,13 +5,7 @@
 
   protected function getParameterValue(array $request, $key) {
     $value = parent::getParameterValue($request, $key);
-
-    if (!is_int($value)) {
-      $this->raiseValidationException(
-        $request,
-        $key,
-        pht('Expected epoch timestamp as integer, got something else.'));
-    }
+    $value = $this->parseIntValue($request, $key, $value);
 
     if ($value <= 0) {
       $this->raiseValidationException(
diff --git a/src/applications/conduit/parametertype/ConduitIntListParameterType.php b/src/applications/conduit/parametertype/ConduitIntListParameterType.php
--- a/src/applications/conduit/parametertype/ConduitIntListParameterType.php
+++ b/src/applications/conduit/parametertype/ConduitIntListParameterType.php
@@ -7,15 +7,7 @@
     $list = parent::getParameterValue($request, $key);
 
     foreach ($list as $idx => $item) {
-      if (!is_int($item)) {
-        $this->raiseValidationException(
-          $request,
-          $key,
-          pht(
-            'Expected a list of integers, but item with index "%s" is '.
-            'not an integer.',
-            $idx));
-      }
+      $list[$idx] = $this->parseIntValue($request, $key.'['.$idx.']', $item);
     }
 
     return $list;
diff --git a/src/applications/conduit/parametertype/ConduitIntParameterType.php b/src/applications/conduit/parametertype/ConduitIntParameterType.php
--- a/src/applications/conduit/parametertype/ConduitIntParameterType.php
+++ b/src/applications/conduit/parametertype/ConduitIntParameterType.php
@@ -5,15 +5,7 @@
 
   protected function getParameterValue(array $request, $key) {
     $value = parent::getParameterValue($request, $key);
-
-    if (!is_int($value)) {
-      $this->raiseValidationException(
-        $request,
-        $key,
-        pht('Expected integer, got something else.'));
-    }
-
-    return $value;
+    return $this->parseIntValue($request, $key, $value);
   }
 
   protected function getParameterTypeName() {
diff --git a/src/applications/conduit/parametertype/ConduitListParameterType.php b/src/applications/conduit/parametertype/ConduitListParameterType.php
--- a/src/applications/conduit/parametertype/ConduitListParameterType.php
+++ b/src/applications/conduit/parametertype/ConduitListParameterType.php
@@ -48,17 +48,9 @@
     return $value;
   }
 
-  protected function validateStringList(array $request, $key, array $list) {
+  protected function parseStringList(array $request, $key, array $list) {
     foreach ($list as $idx => $item) {
-      if (!is_string($item)) {
-        $this->raiseValidationException(
-          $request,
-          $key,
-          pht(
-            'Expected a list of strings, but item with index "%s" is '.
-            'not a string.',
-            $idx));
-      }
+      $list[$idx] = $this->parseStringValue($request, $key.'['.$idx.']', $item);
     }
 
     return $list;
diff --git a/src/applications/conduit/parametertype/ConduitPHIDListParameterType.php b/src/applications/conduit/parametertype/ConduitPHIDListParameterType.php
--- a/src/applications/conduit/parametertype/ConduitPHIDListParameterType.php
+++ b/src/applications/conduit/parametertype/ConduitPHIDListParameterType.php
@@ -5,7 +5,7 @@
 
   protected function getParameterValue(array $request, $key) {
     $list = parent::getParameterValue($request, $key);
-    return $this->validateStringList($request, $key, $list);
+    return $this->parseStringList($request, $key, $list);
   }
 
   protected function getParameterTypeName() {
diff --git a/src/applications/conduit/parametertype/ConduitParameterType.php b/src/applications/conduit/parametertype/ConduitParameterType.php
--- a/src/applications/conduit/parametertype/ConduitParameterType.php
+++ b/src/applications/conduit/parametertype/ConduitParameterType.php
@@ -93,6 +93,53 @@
     return array($key);
   }
 
+  protected function parseStringValue(array $request, $key, $value) {
+    if (!is_string($value)) {
+      $this->raiseValidationException(
+        $request,
+        $key,
+        pht('Expected string, got something else.'));
+    }
+    return $value;
+  }
+
+  protected function parseIntValue(array $request, $key, $value) {
+    if (is_string($value) && ctype_digit($value)) {
+      $value = $value + 0;
+      if (!is_int($value)) {
+        $this->raiseValidationException(
+          $request,
+          $key,
+          pht('Integer overflow.'));
+      }
+    } else if (!is_int($value)) {
+      $this->raiseValidationException(
+        $request,
+        $key,
+        pht('Expected integer, got something else.'));
+    }
+    return $value;
+  }
+
+  protected function parseBoolValue(array $request, $key, $value) {
+    $bool_strings = array(
+      '0' => false,
+      '1' => true,
+      'false' => false,
+      'true' => true,
+    );
+
+    if (is_string($value) && isset($bool_strings[$value])) {
+      $value = $bool_strings[$value];
+    } else if (!is_bool($value)) {
+      $this->raiseValidationException(
+        $request,
+        $key,
+        pht('Expected boolean (true or false), got something else.'));
+    }
+    return $value;
+  }
+
   abstract protected function getParameterTypeName();
 
 
diff --git a/src/applications/conduit/parametertype/ConduitProjectListParameterType.php b/src/applications/conduit/parametertype/ConduitProjectListParameterType.php
--- a/src/applications/conduit/parametertype/ConduitProjectListParameterType.php
+++ b/src/applications/conduit/parametertype/ConduitProjectListParameterType.php
@@ -5,7 +5,7 @@
 
   protected function getParameterValue(array $request, $key) {
     $list = parent::getParameterValue($request, $key);
-    $list = $this->validateStringList($request, $key, $list);
+    $list = $this->parseStringList($request, $key, $list);
     return id(new PhabricatorProjectPHIDResolver())
       ->setViewer($this->getViewer())
       ->resolvePHIDs($list);
diff --git a/src/applications/conduit/parametertype/ConduitStringListParameterType.php b/src/applications/conduit/parametertype/ConduitStringListParameterType.php
--- a/src/applications/conduit/parametertype/ConduitStringListParameterType.php
+++ b/src/applications/conduit/parametertype/ConduitStringListParameterType.php
@@ -5,7 +5,7 @@
 
   protected function getParameterValue(array $request, $key) {
     $list = parent::getParameterValue($request, $key);
-    return $this->validateStringList($request, $key, $list);
+    return $this->parseStringList($request, $key, $list);
   }
 
   protected function getParameterTypeName() {
diff --git a/src/applications/conduit/parametertype/ConduitStringParameterType.php b/src/applications/conduit/parametertype/ConduitStringParameterType.php
--- a/src/applications/conduit/parametertype/ConduitStringParameterType.php
+++ b/src/applications/conduit/parametertype/ConduitStringParameterType.php
@@ -5,15 +5,7 @@
 
   protected function getParameterValue(array $request, $key) {
     $value = parent::getParameterValue($request, $key);
-
-    if (!is_string($value)) {
-      $this->raiseValidationException(
-        $request,
-        $key,
-        pht('Expected string, got something else.'));
-    }
-
-    return $value;
+    return $this->parseStringValue($request, $key, $value);
   }
 
   protected function getParameterTypeName() {
diff --git a/src/applications/conduit/parametertype/ConduitUserListParameterType.php b/src/applications/conduit/parametertype/ConduitUserListParameterType.php
--- a/src/applications/conduit/parametertype/ConduitUserListParameterType.php
+++ b/src/applications/conduit/parametertype/ConduitUserListParameterType.php
@@ -5,7 +5,7 @@
 
   protected function getParameterValue(array $request, $key) {
     $list = parent::getParameterValue($request, $key);
-    $list = $this->validateStringList($request, $key, $list);
+    $list = $this->parseStringList($request, $key, $list);
     return id(new PhabricatorUserPHIDResolver())
       ->setViewer($this->getViewer())
       ->resolvePHIDs($list);