diff --git a/.github/workflows/test-package.yml b/.github/workflows/test-package.yml
index e29229fa..37d8537a 100644
--- a/.github/workflows/test-package.yml
+++ b/.github/workflows/test-package.yml
@@ -29,6 +29,7 @@ jobs:
       with:
         php-version: ${{ matrix.php-version }}
         coverage: none
+        extensions: intl, mbstring
 
     - run: composer validate
 
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 76447871..8af31da3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,13 @@ Changelog
 * Add a "discard classes" configuration option that allows events to be discarded based on the exception class name or PHP error name
   [#622](https://github.com/bugsnag/bugsnag-php/pull/622)
 
+* Add a "redacted keys" configuration option. This is similar to `filters` but allows both strings and regexes. String matching is exact but case-insensitive. Regex matching allows for partial and wildcard matching.
+  [#623](https://github.com/bugsnag/bugsnag-php/pull/623)
+
+### Deprecations
+
+* The `filters` configuration option is now deprecated as `redactedKeys` can express everything that filters could and more.
+
 ## 3.25.0 (2020-11-25)
 
 ### Enhancements
diff --git a/src/Client.php b/src/Client.php
index 7800230e..4a2cb825 100644
--- a/src/Client.php
+++ b/src/Client.php
@@ -532,6 +532,8 @@ public function shouldNotify()
      *
      * Eg. ['password', 'credit_card'].
      *
+     * @deprecated Use redactedKeys instead
+     *
      * @param string[] $filters an array of metaData filters
      *
      * @return $this
@@ -546,7 +548,9 @@ public function setFilters(array $filters)
     /**
      * Get the array of metaData filters.
      *
-     * @var string
+     * @deprecated Use redactedKeys instead
+     *
+     * @var string[]
      */
     public function getFilters()
     {
@@ -987,4 +991,28 @@ public function getDiscardClasses()
     {
         return $this->config->getDiscardClasses();
     }
+
+    /**
+     * Set the array of metadata keys that should be redacted.
+     *
+     * @param string[] $redactedKeys
+     *
+     * @return $this
+     */
+    public function setRedactedKeys(array $redactedKeys)
+    {
+        $this->config->setRedactedKeys($redactedKeys);
+
+        return $this;
+    }
+
+    /**
+     * Get the array of metadata keys that should be redacted.
+     *
+     * @var string[]
+     */
+    public function getRedactedKeys()
+    {
+        return $this->config->getRedactedKeys();
+    }
 }
diff --git a/src/Configuration.php b/src/Configuration.php
index 8fdeccc3..9dd8bc7d 100644
--- a/src/Configuration.php
+++ b/src/Configuration.php
@@ -43,6 +43,8 @@ class Configuration
     /**
      * The strings to filter out from metaData.
      *
+     * @deprecated Use redactedKeys instead
+     *
      * @var string[]
      */
     protected $filters = [
@@ -170,6 +172,13 @@ class Configuration
      */
     protected $discardClasses = [];
 
+    /**
+     * An array of metadata keys that should be redacted.
+     *
+     * @var string[]
+     */
+    protected $redactedKeys = [];
+
     /**
      * Create a new config instance.
      *
@@ -261,6 +270,8 @@ public function shouldNotify()
      *
      * Eg. ['password', 'credit_card'].
      *
+     * @deprecated Use redactedKeys instead
+     *
      * @param string[] $filters an array of metaData filters
      *
      * @return $this
@@ -275,7 +286,9 @@ public function setFilters(array $filters)
     /**
      * Get the array of metaData filters.
      *
-     * @var string
+     * @deprecated Use redactedKeys instead
+     *
+     * @var string[]
      */
     public function getFilters()
     {
@@ -836,4 +849,28 @@ public function getDiscardClasses()
     {
         return $this->discardClasses;
     }
+
+    /**
+     * Set the array of metadata keys that should be redacted.
+     *
+     * @param string[] $redactedKeys
+     *
+     * @return $this
+     */
+    public function setRedactedKeys(array $redactedKeys)
+    {
+        $this->redactedKeys = $redactedKeys;
+
+        return $this;
+    }
+
+    /**
+     * Get the array of metadata keys that should be redacted.
+     *
+     * @var string[]
+     */
+    public function getRedactedKeys()
+    {
+        return $this->redactedKeys;
+    }
 }
diff --git a/src/Report.php b/src/Report.php
index f3d470cb..8a1dfd9b 100644
--- a/src/Report.php
+++ b/src/Report.php
@@ -785,11 +785,21 @@ protected function cleanupObj($obj, $isMetaData)
      */
     protected function shouldFilter($key, $isMetaData)
     {
-        if ($isMetaData) {
-            foreach ($this->config->getFilters() as $filter) {
-                if (stripos($key, $filter) !== false) {
-                    return true;
-                }
+        if (!$isMetaData) {
+            return false;
+        }
+
+        foreach ($this->config->getFilters() as $filter) {
+            if (stripos($key, $filter) !== false) {
+                return true;
+            }
+        }
+
+        foreach ($this->config->getRedactedKeys() as $redactedKey) {
+            if (@preg_match($redactedKey, $key) === 1) {
+                return true;
+            } elseif (Utils::stringCaseEquals($redactedKey, $key)) {
+                return true;
             }
         }
 
diff --git a/src/Utils.php b/src/Utils.php
index 5529061e..fbac1088 100644
--- a/src/Utils.php
+++ b/src/Utils.php
@@ -2,6 +2,8 @@
 
 namespace Bugsnag;
 
+use Normalizer;
+
 class Utils
 {
     /**
@@ -40,4 +42,50 @@ public static function getBuilderName()
 
         return $builderName;
     }
+
+    /**
+     * Check if two strings are equal, ignoring case.
+     *
+     * @param string $a
+     * @param string $b
+     *
+     * @return bool
+     */
+    public static function stringCaseEquals($a, $b)
+    {
+        // Avoid unicode normalisation and MB comparison if possible
+        if (strcasecmp($a, $b) === 0) {
+            return true;
+        }
+
+        // Normalise code points into their decomposed form. For example "ñ"
+        // can be a single code point (U+00F1) or "n" (U+006E) with a combining
+        // tilde (U+0303). The decomposed form will always represent this as
+        // U+006E and U+0303, which means we'll match strings more accurately
+        // and makes case-insensitive comparisons easier
+        if (function_exists('normalizer_is_normalized')
+            && function_exists('normalizer_normalize')
+        ) {
+            $form = Normalizer::NFD;
+
+            if (!normalizer_is_normalized($a, $form)) {
+                $a = normalizer_normalize($a, $form);
+            }
+
+            if (!normalizer_is_normalized($b, $form)) {
+                $b = normalizer_normalize($b, $form);
+            }
+        }
+
+        if (function_exists('mb_stripos') && function_exists('mb_strlen')) {
+            // There's no MB equivalent to strcasecmp, so we have to use
+            // mb_stripos with a length check instead
+            return mb_strlen($a) === mb_strlen($b) && mb_stripos($a, $b) === 0;
+        }
+
+        // If the MB extension isn't available we can still use strcasecmp
+        // This will still work for multi-byte strings in some cases because
+        // the strings were normalised
+        return strcasecmp($a, $b) === 0;
+    }
 }
diff --git a/tests/ClientTest.php b/tests/ClientTest.php
index 8205eaa9..441e59ad 100644
--- a/tests/ClientTest.php
+++ b/tests/ClientTest.php
@@ -1197,6 +1197,20 @@ public function testDiscardClassesCanBeSet()
         $this->assertSame($discardClasses, $this->client->getDiscardClasses());
     }
 
+    public function testRedactedKeysDefault()
+    {
+        $this->assertSame([], $this->client->getRedactedKeys());
+    }
+
+    public function testRedactedKeysCanBeSet()
+    {
+        $redactedKeys = ['password', 'password_confirmation'];
+
+        $this->client->setRedactedKeys($redactedKeys);
+
+        $this->assertSame($redactedKeys, $this->client->getRedactedKeys());
+    }
+
     private function getGuzzleOption($guzzle, $name)
     {
         if (GuzzleCompat::isUsingGuzzle5()) {
diff --git a/tests/ConfigurationTest.php b/tests/ConfigurationTest.php
index 235ac860..7c04d260 100644
--- a/tests/ConfigurationTest.php
+++ b/tests/ConfigurationTest.php
@@ -344,4 +344,18 @@ public function testDiscardClassesCanBeSet()
 
         $this->assertSame($discardClasses, $this->config->getDiscardClasses());
     }
+
+    public function testRedactedKeysDefault()
+    {
+        $this->assertSame([], $this->config->getRedactedKeys());
+    }
+
+    public function testRedactedKeysCanBeSet()
+    {
+        $redactedKeys = ['password', 'password_confirmation'];
+
+        $this->config->setRedactedKeys($redactedKeys);
+
+        $this->assertSame($redactedKeys, $this->config->getRedactedKeys());
+    }
 }
diff --git a/tests/ReportTest.php b/tests/ReportTest.php
index 60cf4b9c..50b7806e 100644
--- a/tests/ReportTest.php
+++ b/tests/ReportTest.php
@@ -3,6 +3,7 @@
 namespace Bugsnag\Tests;
 
 use BadMethodCallException;
+use Bugsnag\Breadcrumbs\Breadcrumb;
 use Bugsnag\Configuration;
 use Bugsnag\Report;
 use Bugsnag\Stacktrace;
@@ -178,6 +179,160 @@ public function testFiltersAreCaseInsensitive()
         );
     }
 
+    /**
+     * @dataProvider redactedKeysProvider
+     *
+     * @param array $metadata
+     * @param string[] $redactedKeys
+     * @param array $expected
+     *
+     * @return void
+     */
+    public function testRedactedKeys(
+        array $metadata,
+        array $redactedKeys,
+        array $expected
+    ) {
+        $this->config->setRedactedKeys($redactedKeys);
+        $this->report->setMetaData(['Testing' => $metadata]);
+
+        $actual = $this->report->toArray()['metaData']['Testing'];
+
+        $this->assertEquals($expected, $actual);
+    }
+
+    /**
+     * @dataProvider redactedKeysProvider
+     *
+     * @param array $metadata
+     * @param string[] $redactedKeys
+     * @param array $expected
+     *
+     * @return void
+     */
+    public function testRedactedKeysWithBreadcrumbMetadata(
+        array $metadata,
+        array $redactedKeys,
+        array $expected
+    ) {
+        $this->config->setRedactedKeys($redactedKeys);
+
+        $breadcrumb = new Breadcrumb('abc', Breadcrumb::LOG_TYPE, ['Testing' => $metadata]);
+        $this->report->addBreadcrumb($breadcrumb);
+
+        $actual = $this->report->toArray()['breadcrumbs'][0]['metaData']['Testing'];
+
+        $this->assertEquals($expected, $actual);
+    }
+
+    public function redactedKeysProvider()
+    {
+        yield [
+            ['abc' => 'xyz', 'a' => 1, 'b' => 2, 'c' => 3],
+            ['a', 'c'],
+            ['abc' => 'xyz', 'a' => '[FILTERED]', 'b' => 2, 'c' => '[FILTERED]'],
+        ];
+
+        yield [
+            ['abc' => 'xyz', 'a' => 1, 'b' => 2, 'C' => 3],
+            ['A', 'c'],
+            ['abc' => 'xyz', 'a' => '[FILTERED]', 'b' => 2, 'C' => '[FILTERED]'],
+        ];
+
+        yield [
+            ['â' => 1, 'b' => 2, 'ñ' => 3, 'n' => 4],
+            ['â', 'ñ'],
+            ['â' => '[FILTERED]', 'b' => 2, 'ñ' => '[FILTERED]', 'n' => 4],
+        ];
+
+        yield [
+            ['â' => 1, 'b' => 2, 'Ñ' => 3],
+            ['Â', 'ñ'],
+            ['â' => '[FILTERED]', 'b' => 2, 'Ñ' => '[FILTERED]'],
+        ];
+
+        // 6e cc 83 is equivalent to "\u{006E}\u{0303}" but in a way PHP 5 can
+        // understand. This is the character "ñ" built out of "n" and a
+        // combining tilde
+        yield [
+            ["\x6e\xcc\x83" => 1, 'b' => 2, 'c' => 3, 'n' => 4],
+            ["\x6e\xcc\x83", 'c'],
+            ["\x6e\xcc\x83" => '[FILTERED]', 'b' => 2, 'c' => '[FILTERED]', 'n' => 4],
+        ];
+
+        // 4e cc 83 is equivalent to "\u{004E}\u{0303}", which is the capital
+        // version of the above ("N" + a combining tilde)
+        yield [
+            ["\x6e\xcc\x83" => 1, 'b' => 2, 'c' => 3, 'n' => 4],
+            ["\x4e\xcc\x83", 'c'],
+            ["\x6e\xcc\x83" => '[FILTERED]', 'b' => 2, 'c' => '[FILTERED]', 'n' => 4],
+        ];
+
+        // This is "ñ" both as a single character and with the combining tilde
+        yield [
+            ["\x6e\xcc\x83" => 1, 'b' => 2, 'c' => 3, 'n' => 4],
+            ["\xc3\xb1", 'c'],
+            ["\x6e\xcc\x83" => '[FILTERED]', 'b' => 2, 'c' => '[FILTERED]', 'n' => 4],
+        ];
+
+        // This is "Ñ" as a single character and "ñ" with the combining tilde
+        yield [
+            ["\x6e\xcc\x83" => 1, 'b' => 2, 'c' => 3, 'n' => 4],
+            ["\xc3\x91", 'c'],
+            ["\x6e\xcc\x83" => '[FILTERED]', 'b' => 2, 'c' => '[FILTERED]', 'n' => 4],
+        ];
+
+        // This is "Ñ" as a single character and "ñ" with the combining tilde
+        yield [
+            ["\xc3\x91" => 1, 'b' => 2, 'c' => 3, 'n' => 4],
+            ["\x6e\xcc\x83", 'c'],
+            ["\xc3\x91" => '[FILTERED]', 'b' => 2, 'c' => '[FILTERED]', 'n' => 4],
+        ];
+
+        yield [
+            ['abc' => 1, 'xyz' => 2],
+            ['/^.b.$/'],
+            ['abc' => '[FILTERED]', 'xyz' => 2],
+        ];
+
+        yield [
+            ['abc' => 1, 'xyz' => 2, 'oOo' => 3],
+            ['/^[a-z]{3}$/'],
+            ['abc' => '[FILTERED]', 'xyz' => '[FILTERED]', 'oOo' => 3],
+        ];
+
+        yield [
+            ['abc' => 1, 'xyz' => 2, 'oOo' => 3, 'oOoOo' => 4],
+            ['/^[A-z]{3}$/'],
+            ['abc' => '[FILTERED]', 'xyz' => '[FILTERED]', 'oOo' => '[FILTERED]', 'oOoOo' => 4],
+        ];
+
+        yield [
+            ['abc' => 1, 'xyz' => 2, 'yyy' => 3],
+            ['/(c|y)$/'],
+            ['abc' => '[FILTERED]', 'xyz' => 2, 'yyy' => '[FILTERED]'],
+        ];
+
+        yield [
+            ['abc' => 1, 'xyz' => 2, 'yyy' => 3],
+            ['/c$/', '/y$/'],
+            ['abc' => '[FILTERED]', 'xyz' => 2, 'yyy' => '[FILTERED]'],
+        ];
+
+        // This doesn't match the regex but does match as a string comparison
+        yield [
+            ['/^abc$/' => 1, 'xyz' => 2, 'oOo' => 3],
+            ['/^abc$/'],
+            ['/^abc$/' => '[FILTERED]', 'xyz' => 2, 'oOo' => 3],
+        ];
+
+        yield [
+            ['/abc/' => 1, 'xyz' => 2, 'oOo' => 3],
+            ['/abc/'],
+            ['/abc/' => '[FILTERED]', 'xyz' => 2, 'oOo' => 3],
+        ];
+    }
+
     public function testCanGetStacktrace()
     {
         $beginningOfTest = __LINE__;
diff --git a/tests/UtilsTest.php b/tests/UtilsTest.php
new file mode 100644
index 00000000..162bba47
--- /dev/null
+++ b/tests/UtilsTest.php
@@ -0,0 +1,111 @@
+<?php
+
+namespace Bugsnag\Tests;
+
+use Bugsnag\Utils;
+
+class UtilsTest extends TestCase
+{
+    /**
+     * @dataProvider stringCaseEqualsProvider
+     *
+     * @param string $a
+     * @param string $b
+     * @param bool $expected
+     * @param string|null $requiredVersion
+     *
+     * @return void
+     */
+    public function testStringCaseEquals($a, $b, $expected, $requiredVersion = null)
+    {
+        if ($requiredVersion !== null) {
+            if (version_compare(PHP_VERSION, $requiredVersion, '<')) {
+                $this->markTestSkipped("This test requires at least PHP {$requiredVersion} to run");
+            }
+        }
+
+        $this->assertSame(
+            $expected,
+            Utils::stringCaseEquals($a, $b),
+            sprintf(
+                'Expected "%s" %s "%s"',
+                $a,
+                $expected ? 'to equal' : 'not to equal',
+                $b
+            )
+        );
+
+        $this->assertSame(
+            $expected,
+            Utils::stringCaseEquals($b, $a),
+            sprintf(
+                'Expected "%s" %s "%s"',
+                $b,
+                $expected ? 'to equal' : 'not to equal',
+                $a
+            )
+        );
+    }
+
+    public function stringCaseEqualsProvider()
+    {
+        yield ['a', 'a', true];
+        yield ['a', 'A', true];
+        yield ['A', 'A', true];
+
+        yield ['a', 'b', false];
+        yield ['c', 'b', false];
+
+        yield ['jalapeño', 'jalapeño', true];
+        yield ['JALAPEÑO', 'jalapeño', true];
+        yield ['JaLaPeÑo', 'jAlApEñO', true];
+        yield ['jalapeño', 'jalapeno', false];
+
+        // 6e cc 83 is equivalent to "\u{006E}\u{0303}" but in a way PHP 5 can
+        // understand. This is the character "ñ" built out of "n" and a
+        // combining tilde
+        yield ["jalape\x6e\xcc\x83o", "jalape\x6e\xcc\x83o", true];
+        yield ["jalape\x6e\xcc\x83o", 'jalapeño', true];
+
+        // 4e cc 83 is equivalent to "\u{004E}\u{0303}", which is the capital
+        // version of the above ("N" + a combining tilde)
+        yield ["jalape\x6e\xcc\x83o", "jalape\x4e\xcc\x83o", true];
+
+        // This is "ñ" both as a single character and with the combining tilde
+        yield ["jalape\x6e\xcc\x83o", "jalape\xc3\xb1o", true];
+
+        // This is "Ñ" as a single character and "ñ" with the combining tilde
+        yield ["jalape\x6e\xcc\x83o", "jalape\xc3\x91o", true];
+
+        yield ["jalape\x6e\xcc\x83o", 'jalapeno', false];
+
+        // This test fails with a simple strcasecmp, proving that the MB string
+        // functions are necessary in some cases
+        // This requires PHP 7.3, which contains many MB String improvements:
+        // https://www.php.net/manual/en/migration73.new-features.php#migration73.new-features.mbstring
+        yield ['größer', 'gröẞer', true, '7.3.0'];
+        yield ['größer', 'GRÖẞER', true, '7.3.0'];
+
+        // Tests with characters from various unicode planes
+
+        yield ['Iñtërnâtiônàližætiøn', 'Iñtërnâtiônàližætiøn', true];
+        yield ['iñtërnâtiônàližætiøn', 'IÑTËRNÂTIÔNÀLIŽÆTIØN', true, '5.6.0'];
+
+        yield ['обичам те', 'обичам те', true];
+        yield ['обичам те', 'ОБИЧАМ ТЕ', true, '5.6.0'];
+        yield ['ОбИчАм Те', 'оБиЧаМ тЕ', true, '5.6.0'];
+        yield ['обичам те', 'oбичam te', false];
+
+        yield ['大好きだよ', '大好きだよ', true];
+        yield ['أحبك', 'أحبك', true];
+
+        yield ['😀😀', '😀😀', true];
+
+        yield ['👨‍👩‍👧‍👦🇬🇧', '👨‍👩‍👧‍👦🇬🇧', true];
+        yield ['🇬🇧👨‍👩‍👧‍👦', '👨‍👩‍👧‍👦🇬🇧', false];
+
+        $ukFlag = "\xf0\x9f\x87\xac\xf0\x9f\x87\xa7";
+        yield ['👨‍👩‍👧‍👦'.$ukFlag, '👨‍👩‍👧‍👦🇬🇧', true];
+        yield [$ukFlag.'👨‍👩‍👧‍👦', '👨‍👩‍👧‍👦🇬🇧', false];
+    }
+}
diff --git a/tests/phpt/handler_should_increase_memory_limit_by_configured_amount_on_oom.phpt b/tests/phpt/handler_should_increase_memory_limit_by_configured_amount_on_oom.phpt
index 46ac7442..dc551117 100644
--- a/tests/phpt/handler_should_increase_memory_limit_by_configured_amount_on_oom.phpt
+++ b/tests/phpt/handler_should_increase_memory_limit_by_configured_amount_on_oom.phpt
@@ -5,24 +5,24 @@ Bugsnag\Handler should increase the memory limit by the configured amount when a
 $client = require __DIR__ . '/_prelude.php';
 $client->setMemoryLimitIncrease(1024 * 1024 * 10);
 
-ini_set('memory_limit', '2M');
+Bugsnag\Handler::register($client);
+
+ini_set('memory_limit', 1024 * 1024 * 5);
 var_dump(ini_get('memory_limit'));
 
 $client->registerCallback(function () {
     var_dump(ini_get('memory_limit'));
 });
 
-Bugsnag\Handler::register($client);
-
 $a = str_repeat('a', 2147483647);
 
 echo "No OOM!\n";
 ?>
 --EXPECTF--
-string(2) "2M"
+string(7) "5242880"
 
 Fatal error: Allowed memory size of %d bytes exhausted (tried to allocate %d bytes) in %s on line 14
-string(8) "12582912"
+string(8) "15728640"
 Guzzle request made (1 event)!
 * Method: 'POST'
 * URI: 'http://localhost/notify'