diff --git a/src/applications/conduit/call/ConduitCall.php b/src/applications/conduit/call/ConduitCall.php
--- a/src/applications/conduit/call/ConduitCall.php
+++ b/src/applications/conduit/call/ConduitCall.php
@@ -15,7 +15,7 @@
   private $request;
   private $user;
 
-  public function __construct($method, array $params) {
+  public function __construct($method, array $params, $strictly_typed = true) {
     $this->method = $method;
     $this->handler = $this->buildMethodHandler($method);
 
@@ -41,7 +41,7 @@
           "'".implode("', '", array_keys($invalid_params))."'"));
     }
 
-    $this->request = new ConduitAPIRequest($params);
+    $this->request = new ConduitAPIRequest($params, $strictly_typed);
   }
 
   public function getAPIRequest() {
diff --git a/src/applications/conduit/controller/PhabricatorConduitAPIController.php b/src/applications/conduit/controller/PhabricatorConduitAPIController.php
--- a/src/applications/conduit/controller/PhabricatorConduitAPIController.php
+++ b/src/applications/conduit/controller/PhabricatorConduitAPIController.php
@@ -25,9 +25,11 @@
 
     try {
 
-      list($metadata, $params) = $this->decodeConduitParams($request, $method);
+      list($metadata, $params, $strictly_typed) = $this->decodeConduitParams(
+        $request,
+        $method);
 
-      $call = new ConduitCall($method, $params);
+      $call = new ConduitCall($method, $params, $strictly_typed);
       $method_implementation = $call->getMethodImplementation();
 
       $result = null;
@@ -638,7 +640,7 @@
       $metadata = idx($params, '__conduit__', array());
       unset($params['__conduit__']);
 
-      return array($metadata, $params);
+      return array($metadata, $params, true);
     }
 
     // Otherwise, look for a single parameter called 'params' which has the
@@ -659,7 +661,7 @@
       $metadata = idx($params, '__conduit__', array());
       unset($params['__conduit__']);
 
-      return array($metadata, $params);
+      return array($metadata, $params, true);
     }
 
     // If we do not have `params`, assume this is a simple HTTP request with
@@ -675,7 +677,7 @@
       }
     }
 
-    return array($metadata, $params);
+    return array($metadata, $params, false);
   }
 
   private function authorizeOAuthMethodAccess(
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
@@ -3,17 +3,9 @@
 final class ConduitBoolParameterType
   extends ConduitParameterType {
 
-  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;
+  protected function getParameterValue(array $request, $key, $strict) {
+    $value = parent::getParameterValue($request, $key, $strict);
+    return $this->parseBoolValue($request, $key, $value, $strict);
   }
 
   protected function getParameterTypeName() {
diff --git a/src/applications/conduit/parametertype/ConduitColumnsParameterType.php b/src/applications/conduit/parametertype/ConduitColumnsParameterType.php
--- a/src/applications/conduit/parametertype/ConduitColumnsParameterType.php
+++ b/src/applications/conduit/parametertype/ConduitColumnsParameterType.php
@@ -3,10 +3,10 @@
 final class ConduitColumnsParameterType
   extends ConduitParameterType {
 
-  protected function getParameterValue(array $request, $key) {
+  protected function getParameterValue(array $request, $key, $strict) {
     // We don't do any meaningful validation here because the transaction
     // itself validates everything and the input format is flexible.
-    return parent::getParameterValue($request, $key);
+    return parent::getParameterValue($request, $key, $strict);
   }
 
   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
@@ -3,15 +3,9 @@
 final class ConduitEpochParameterType
   extends ConduitParameterType {
 
-  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.'));
-    }
+  protected function getParameterValue(array $request, $key, $strict) {
+    $value = parent::getParameterValue($request, $key, $strict);
+    $value = $this->parseIntValue($request, $key, $value, $strict);
 
     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
@@ -3,19 +3,11 @@
 final class ConduitIntListParameterType
   extends ConduitListParameterType {
 
-  protected function getParameterValue(array $request, $key) {
-    $list = parent::getParameterValue($request, $key);
+  protected function getParameterValue(array $request, $key, $strict) {
+    $list = parent::getParameterValue($request, $key, $strict);
 
     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
@@ -3,17 +3,9 @@
 final class ConduitIntParameterType
   extends ConduitParameterType {
 
-  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;
+  protected function getParameterValue(array $request, $key, $strict) {
+    $value = parent::getParameterValue($request, $key, $strict);
+    return $this->parseIntValue($request, $key, $value, $strict);
   }
 
   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
@@ -14,8 +14,8 @@
     return $this->allowEmptyList;
   }
 
-  protected function getParameterValue(array $request, $key) {
-    $value = parent::getParameterValue($request, $key);
+  protected function getParameterValue(array $request, $key, $strict) {
+    $value = parent::getParameterValue($request, $key, $strict);
 
     if (!is_array($value)) {
       $this->raiseValidationException(
@@ -48,17 +48,18 @@
     return $value;
   }
 
-  protected function validateStringList(array $request, $key, array $list) {
+  protected function parseStringList(
+    array $request,
+    $key,
+    array $list,
+    $strict) {
+
     foreach ($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,
+        $strict);
     }
 
     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
@@ -3,9 +3,9 @@
 final class ConduitPHIDListParameterType
   extends ConduitListParameterType {
 
-  protected function getParameterValue(array $request, $key) {
-    $list = parent::getParameterValue($request, $key);
-    return $this->validateStringList($request, $key, $list);
+  protected function getParameterValue(array $request, $key, $strict) {
+    $list = parent::getParameterValue($request, $key, $strict);
+    return $this->parseStringList($request, $key, $list, $strict);
   }
 
   protected function getParameterTypeName() {
diff --git a/src/applications/conduit/parametertype/ConduitPHIDParameterType.php b/src/applications/conduit/parametertype/ConduitPHIDParameterType.php
--- a/src/applications/conduit/parametertype/ConduitPHIDParameterType.php
+++ b/src/applications/conduit/parametertype/ConduitPHIDParameterType.php
@@ -3,8 +3,8 @@
 final class ConduitPHIDParameterType
   extends ConduitParameterType {
 
-  protected function getParameterValue(array $request, $key) {
-    $value = parent::getParameterValue($request, $key);
+  protected function getParameterValue(array $request, $key, $strict) {
+    $value = parent::getParameterValue($request, $key, $strict);
 
     if (!is_string($value)) {
       $this->raiseValidationException(
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
@@ -30,12 +30,12 @@
   }
 
 
-  final public function getValue(array $request, $key) {
+  final public function getValue(array $request, $key, $strict = true) {
     if (!$this->getExists($request, $key)) {
       return $this->getParameterDefault();
     }
 
-    return $this->getParameterValue($request, $key);
+    return $this->getParameterValue($request, $key, $strict);
   }
 
   final public function getKeys($key) {
@@ -85,7 +85,7 @@
     return array_key_exists($key, $request);
   }
 
-  protected function getParameterValue(array $request, $key) {
+  protected function getParameterValue(array $request, $key, $strict) {
     return $request[$key];
   }
 
@@ -93,6 +93,53 @@
     return array($key);
   }
 
+  protected function parseStringValue(array $request, $key, $value, $strict) {
+    if (!is_string($value)) {
+      $this->raiseValidationException(
+        $request,
+        $key,
+        pht('Expected string, got something else.'));
+    }
+    return $value;
+  }
+
+  protected function parseIntValue(array $request, $key, $value, $strict) {
+    if (!$strict && 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, $strict) {
+    $bool_strings = array(
+      '0' => false,
+      '1' => true,
+      'false' => false,
+      'true' => true,
+    );
+
+    if (!$strict && 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/ConduitPointsParameterType.php b/src/applications/conduit/parametertype/ConduitPointsParameterType.php
--- a/src/applications/conduit/parametertype/ConduitPointsParameterType.php
+++ b/src/applications/conduit/parametertype/ConduitPointsParameterType.php
@@ -3,8 +3,8 @@
 final class ConduitPointsParameterType
   extends ConduitParameterType {
 
-  protected function getParameterValue(array $request, $key) {
-    $value = parent::getParameterValue($request, $key);
+  protected function getParameterValue(array $request, $key, $strict) {
+    $value = parent::getParameterValue($request, $key, $strict);
 
     if (($value !== null) && !is_numeric($value)) {
       $this->raiseValidationException(
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
@@ -3,9 +3,9 @@
 final class ConduitProjectListParameterType
   extends ConduitListParameterType {
 
-  protected function getParameterValue(array $request, $key) {
-    $list = parent::getParameterValue($request, $key);
-    $list = $this->validateStringList($request, $key, $list);
+  protected function getParameterValue(array $request, $key, $strict) {
+    $list = parent::getParameterValue($request, $key, $strict);
+    $list = $this->parseStringList($request, $key, $list, $strict);
     return id(new PhabricatorProjectPHIDResolver())
       ->setViewer($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
@@ -3,9 +3,9 @@
 final class ConduitStringListParameterType
   extends ConduitListParameterType {
 
-  protected function getParameterValue(array $request, $key) {
-    $list = parent::getParameterValue($request, $key);
-    return $this->validateStringList($request, $key, $list);
+  protected function getParameterValue(array $request, $key, $strict) {
+    $list = parent::getParameterValue($request, $key, $strict);
+    return $this->parseStringList($request, $key, $list, $strict);
   }
 
   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
@@ -3,17 +3,9 @@
 final class ConduitStringParameterType
   extends ConduitParameterType {
 
-  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;
+  protected function getParameterValue(array $request, $key, $strict) {
+    $value = parent::getParameterValue($request, $key, $strict);
+    return $this->parseStringValue($request, $key, $value, $strict);
   }
 
   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
@@ -3,9 +3,9 @@
 final class ConduitUserListParameterType
   extends ConduitListParameterType {
 
-  protected function getParameterValue(array $request, $key) {
-    $list = parent::getParameterValue($request, $key);
-    $list = $this->validateStringList($request, $key, $list);
+  protected function getParameterValue(array $request, $key, $strict) {
+    $list = parent::getParameterValue($request, $key, $strict);
+    $list = $this->parseStringList($request, $key, $list, $strict);
     return id(new PhabricatorUserPHIDResolver())
       ->setViewer($this->getViewer())
       ->resolvePHIDs($list);
diff --git a/src/applications/conduit/parametertype/ConduitUserParameterType.php b/src/applications/conduit/parametertype/ConduitUserParameterType.php
--- a/src/applications/conduit/parametertype/ConduitUserParameterType.php
+++ b/src/applications/conduit/parametertype/ConduitUserParameterType.php
@@ -3,8 +3,8 @@
 final class ConduitUserParameterType
   extends ConduitParameterType {
 
-  protected function getParameterValue(array $request, $key) {
-    $value = parent::getParameterValue($request, $key);
+  protected function getParameterValue(array $request, $key, $strict) {
+    $value = parent::getParameterValue($request, $key, $strict);
 
     if ($value === null) {
       return null;
diff --git a/src/applications/conduit/protocol/ConduitAPIRequest.php b/src/applications/conduit/protocol/ConduitAPIRequest.php
--- a/src/applications/conduit/protocol/ConduitAPIRequest.php
+++ b/src/applications/conduit/protocol/ConduitAPIRequest.php
@@ -6,9 +6,11 @@
   private $user;
   private $isClusterRequest = false;
   private $oauthToken;
+  private $isStrictlyTyped = true;
 
-  public function __construct(array $params) {
+  public function __construct(array $params, $strictly_typed) {
     $this->params = $params;
+    $this->isStrictlyTyped = $strictly_typed;
   }
 
   public function getValue($key, $default = null) {
@@ -68,6 +70,10 @@
     return $this->isClusterRequest;
   }
 
+  public function getIsStrictlyTyped() {
+    return $this->isStrictlyTyped;
+  }
+
   public function newContentSource() {
     return PhabricatorContentSource::newForSource(
       PhabricatorConduitContentSource::SOURCECONST);
diff --git a/src/applications/search/engine/PhabricatorApplicationSearchEngine.php b/src/applications/search/engine/PhabricatorApplicationSearchEngine.php
--- a/src/applications/search/engine/PhabricatorApplicationSearchEngine.php
+++ b/src/applications/search/engine/PhabricatorApplicationSearchEngine.php
@@ -1115,7 +1115,9 @@
         continue;
       }
 
-      $value = $field->readValueFromConduitRequest($constraints);
+      $value = $field->readValueFromConduitRequest(
+        $constraints,
+        $request->getIsStrictlyTyped());
       $saved_query->setParameter($field->getKey(), $value);
     }
 
diff --git a/src/applications/search/field/PhabricatorSearchField.php b/src/applications/search/field/PhabricatorSearchField.php
--- a/src/applications/search/field/PhabricatorSearchField.php
+++ b/src/applications/search/field/PhabricatorSearchField.php
@@ -323,10 +323,14 @@
       $this->getConduitKey());
   }
 
-  public function readValueFromConduitRequest(array $constraints) {
+  public function readValueFromConduitRequest(
+    array $constraints,
+    $strict = true) {
+
     return $this->getConduitParameterType()->getValue(
       $constraints,
-      $this->getConduitKey());
+      $this->getConduitKey(),
+      $strict);
   }
 
   public function getValidConstraintKeys() {
diff --git a/src/applications/transactions/editengine/PhabricatorEditEngine.php b/src/applications/transactions/editengine/PhabricatorEditEngine.php
--- a/src/applications/transactions/editengine/PhabricatorEditEngine.php
+++ b/src/applications/transactions/editengine/PhabricatorEditEngine.php
@@ -1903,7 +1903,10 @@
       $parameter_type->setViewer($viewer);
 
       try {
-        $xaction['value'] = $parameter_type->getValue($xaction, 'value');
+        $xaction['value'] = $parameter_type->getValue(
+          $xaction,
+          'value',
+          $request->getIsStrictlyTyped());
       } catch (Exception $ex) {
         throw new PhutilProxyException(
           pht(