diff --git a/src/Bag.php b/src/Bag.php
index b6943fc..4a4e3db 100644
--- a/src/Bag.php
+++ b/src/Bag.php
@@ -8,6 +8,9 @@
 use Normalizer;
 use whikloj\BagItTools\Exceptions\BagItException;
 use whikloj\BagItTools\Exceptions\FilesystemException;
+use whikloj\BagItTools\Exceptions\ProfileException;
+use whikloj\BagItTools\Profiles\BagItProfile;
+use whikloj\BagItTools\Profiles\ProfileFactory;
 use ZipArchive;
 
 /**
@@ -134,14 +137,14 @@ class Bag
     /**
      * All the extensions in one array.
      *
-     * @var array
+     * @var array<string>
      */
     private array $packageExtensions;
 
     /**
      * Array of current bag version with keys 'major' and 'minor'.
      *
-     * @var array
+     * @var array<string, int>
      */
     private array $currentVersion = self::DEFAULT_BAGIT_VERSION;
 
@@ -155,21 +158,21 @@ class Bag
     /**
      * Array of payload manifests.
      *
-     * @var array
+     * @var array<string, PayloadManifest>
      */
     private array $payloadManifests;
 
     /**
      * Array of tag manifests.
      *
-     * @var array
+     * @var array<string, TagManifest>
      */
     private array $tagManifests;
 
     /**
      * List of relative file paths for all files.
      *
-     * @var array
+     * @var array<string>
      */
     private array $payloadFiles;
 
@@ -201,21 +204,21 @@ class Bag
      * supported by the BagIt specification. Stored to avoid extraneous calls
      * to hash_algos().
      *
-     * @var array
+     * @var array<string>
      */
     private array $validHashAlgorithms;
 
     /**
      * Errors when validating a bag.
      *
-     * @var array
+     * @var array<int, array<string, string>>
      */
     private array $bagErrors;
 
     /**
      * Warnings when validating a bag.
      *
-     * @var array
+     * @var array<int, array<string, string>>
      */
     private array $bagWarnings;
 
@@ -229,7 +232,7 @@ class Bag
     /**
      * Bag Info data.
      *
-     * @var array
+     * @var array<int, array<string, string>>
      */
     private array $bagInfoData = [];
 
@@ -237,7 +240,7 @@ class Bag
      * Unique array of all Bag info tags/values. Tags are stored once in lower case with an array of all instances
      * of values. This index does not save order.
      *
-     * @var array
+     * @var array<string, array<string>>
      */
     private array $bagInfoTagIndex = [];
 
@@ -254,6 +257,12 @@ class Bag
      */
     private ?string $serialization = null;
 
+    /**
+     * Array of BagIt profiles.
+     * @var array<int, BagItProfile>
+     */
+    private array $profiles = [];
+
     /**
      * Bag constructor.
      *
@@ -361,6 +370,16 @@ public function isValid(): bool
             $this->mergeErrors($manifest->getErrors());
             $this->mergeWarnings($manifest->getWarnings());
         }
+        foreach ($this->profiles as $profile) {
+            try {
+                $profile->validateBag($this);
+            } catch (ProfileException $e) {
+                $this->addBagError(
+                    $profile->getProfileIdentifier(),
+                    $e->getMessage()
+                );
+            }
+        }
         return (count($this->bagErrors) == 0);
     }
 
@@ -1276,10 +1295,74 @@ public function getSerializationMimeType(): ?string
         return $this->serialization;
     }
 
+    /**
+     * @return array The profiles that have been added to the bag.
+     */
+    public function getBagProfiles(): array
+    {
+        return $this->profiles;
+    }
+
+    /**
+     * Add a profile to the bag.
+     * @param string $url The URL to the profile.
+     * @throws Exceptions\ProfileException If the profile cannot be loaded or parsed.
+     */
+    public function addBagProfileByURL(string $url): void
+    {
+        $this->addBagProfileInternal(ProfileFactory::generateProfileFromUri($url));
+    }
+
+    /**
+     * Add a profile to the bag.
+     * @param string $json The JSON representation of the profile.
+     * @throws Exceptions\ProfileException If the profile cannot be parsed.
+     */
+    public function addBagProfileByJson(string $json): void
+    {
+        $this->addBagProfileInternal(BagItProfile::fromJson($json));
+    }
+
+    /**
+     * Remove a profile from the bag.
+     * @param string $profileId The identifier of the profile to remove.
+     */
+    public function removeBagProfile(string $profileId): void
+    {
+        if (array_key_exists($profileId, $this->profiles)) {
+            unset($this->profiles[$profileId]);
+            $this->changed = true;
+        }
+    }
+
+    /**
+     * Clear all profiles from the bag.
+     */
+    public function clearAllProfiles(): void
+    {
+        if (count($this->profiles) > 0) {
+            $this->profiles = [];
+            $this->changed = true;
+        }
+    }
+
     /*
      *  XXX: Private functions
      */
 
+    /**
+     * Add a profile to the bag if it doesn't already exist.
+     * @param BagItProfile $profile The profile to add.
+     */
+    private function addBagProfileInternal(BagItProfile $profile): void
+    {
+        if (!array_key_exists($profile->getProfileIdentifier(), $this->profiles)) {
+            $this->setExtended(true);
+            $this->profiles[$profile->getProfileIdentifier()] = $profile;
+            $this->changed = true;
+        }
+    }
+
     /**
      * Common checks for interactions with custom tag files.
      * @param string $tagFilePath The relative path to the tag file.
@@ -1963,8 +2046,8 @@ function (&$item) {
             );
         } else {
             $this->currentVersion = [
-                'major' => $match[1],
-                'minor' => $match[2],
+                'major' => (int)$match[1],
+                'minor' => (int)$match[2],
             ];
         }
         if (
@@ -2188,7 +2271,12 @@ private static function untarBag(string $filename): string
     private static function extensionTarCompression(string $filename): ?string
     {
         $filename = strtolower(basename($filename));
-        return (str_ends_with($filename, '.bz2') ? 'bz2' : (str_ends_with($filename, 'gz') ? 'gz' : null));
+        if (str_ends_with($filename, '.bz2')) {
+            return 'bz2';
+        } elseif (str_ends_with($filename, '.gz') || str_ends_with($filename, '.tgz')) {
+            return 'gz';
+        }
+        return null;
     }
 
     /**
diff --git a/src/Profiles/BagItProfile.php b/src/Profiles/BagItProfile.php
index 3c6ea7c..a6991b1 100644
--- a/src/Profiles/BagItProfile.php
+++ b/src/Profiles/BagItProfile.php
@@ -923,8 +923,7 @@ public function validateBag(Bag $bag): bool
         }
         if ($this->getManifestsRequired() !== []) {
             $manifests = array_keys($bag->getPayloadManifests());
-            $diff = array_diff($manifests, $this->getManifestsRequired()) +
-                array_diff($this->getManifestsRequired(), $manifests);
+            $diff = array_diff($this->getManifestsRequired(), $manifests);
             if ($diff !== []) {
                 $errors[] = "Profile requires payload manifest(s) which are missing from the bag (" .
                     implode(", ", $diff) . ")";
@@ -940,8 +939,7 @@ public function validateBag(Bag $bag): bool
         }
         if ($this->getTagManifestsRequired() !== []) {
             $manifests = array_keys($bag->getTagManifests());
-            $diff = array_diff($manifests, $this->getTagManifestsRequired()) +
-                array_diff($this->getTagManifestsRequired(), $manifests);
+            $diff = array_diff($this->getTagManifestsRequired(), $manifests);
             if ($diff !== []) {
                 $errors[] = "Profile requires tag manifest(s) which are missing from the bag (" .
                     implode(", ", $diff) . ")";
@@ -959,8 +957,7 @@ public function validateBag(Bag $bag): bool
             // Grab the first tag manifest, they should all be the same
             $manifests = $bag->getTagManifests()[0];
             $tag_files = array_keys($manifests->getHashes());
-            $diff = array_diff($this->getTagFilesRequired(), $tag_files) +
-                array_diff($tag_files, $this->getTagFilesRequired());
+            $diff = array_diff($this->getTagFilesRequired(), $tag_files);
             if ($diff !== []) {
                 $errors[] = "Profile requires tag files(s) which are missing from the bag (" .
                     implode(", ", $diff) . ")";
@@ -980,8 +977,7 @@ public function validateBag(Bag $bag): bool
             // Grab the first tag manifest, they should all be the same
             $manifests = $bag->getPayloadManifests()[0];
             $payload_files = array_keys($manifests->getHashes());
-            $diff = array_diff($this->getPayloadFilesRequired(), $payload_files) +
-                array_diff($payload_files, $this->getPayloadFilesRequired());
+            $diff = array_diff($this->getPayloadFilesRequired(), $payload_files);
             if ($diff !== []) {
                 $errors[] = "Profile requires payload file(s) which are missing from the bag (" .
                     implode(", ", $diff) . ")";
diff --git a/tests/BagItWebserverFramework.php b/tests/BagItWebserverFramework.php
index 56ad14f..4532047 100644
--- a/tests/BagItWebserverFramework.php
+++ b/tests/BagItWebserverFramework.php
@@ -5,10 +5,25 @@
 use donatj\MockWebServer\MockWebServer;
 use donatj\MockWebServer\Response;
 
+/**
+ * Class to setup a mock webserver for testing remote file downloads.
+ * @package whikloj\BagItTools\Test
+ * @since 5.0.0
+ *
+ * To use this abstract class, extend it and then implement the setupBeforeClass methods, define the webserver_files
+ * variable and then call the parent::setUpBeforeClass() method.
+ */
 abstract class BagItWebserverFramework extends BagItTestFramework
 {
     /**
      * Array of remote files defined in mock webserver.
+     * Outside key is a unique identifier, keys for the inside array are:
+     *  filename (string) - path to file with response contents
+     *  headers (array) - headers to return in response
+     *  status_code (int) - status code
+     *  content (string) - string to return, used instead of filename
+     *  path (path) - the path of the URL, used if filename not defined. Otherwise is basename(filename)
+     * @var array<string, array<string, mixed>>
      */
     protected static array $webserver_files = [];
 
@@ -22,19 +37,20 @@ abstract class BagItWebserverFramework extends BagItTestFramework
     /**
      * Array of file contents for use with comparing against requests against the same index in self::$remote_urls
      *
-     * @var string|array|false
+     * @var array<int, mixed>
      */
-    protected static string|array|false $response_content = [];
+    protected static array $response_content = [];
 
     /**
      * Array of mock urls to get responses from. Match response bodies against matching key in self::$response_content
      *
-     * @var string|array
+     * @var array<int, string>
      */
-    protected static string|array $remote_urls = [];
+    protected static array $remote_urls = [];
 
     /**
      * {@inheritdoc}
+     * NOTE: You should override this in your class, define self::$webserver_files, then call parent::setUpBeforeClass
      */
     public static function setUpBeforeClass(): void
     {
@@ -42,14 +58,17 @@ public static function setUpBeforeClass(): void
         self::$webserver->start();
         $counter = 0;
         foreach (self::$webserver_files as $file) {
-            self::$response_content[$counter] = file_get_contents($file['filename']);
+            self::$response_content[$counter] = $file['content'] ?? file_get_contents($file['filename']);
             // Add custom headers if defined.
-            $response_headers = [ 'Cache-Control' => 'no-cache', 'Content-Length' => stat($file['filename'])['size']] +
-                ($file['headers'] ?? []);
+            $response_headers = [
+                'Cache-Control' => 'no-cache',
+                'Content-Length' => isset($file['content']) ? strlen($file['content']) :
+                    stat($file['filename'])['size']
+            ] + ($file['headers'] ?? []);
             // Use custom status code if defined.
             $status_code = $file['status_code'] ?? 200;
             self::$remote_urls[$counter] = self::$webserver->setResponseOfPath(
-                "/example/" . basename($file['filename']),
+                "/" . ($file['path'] ?? "example/" . basename($file['filename'])),
                 new Response(
                     self::$response_content[$counter],
                     $response_headers,
diff --git a/tests/Profiles/BagProfileTest.php b/tests/Profiles/BagProfileTest.php
index 80018e9..639fca5 100644
--- a/tests/Profiles/BagProfileTest.php
+++ b/tests/Profiles/BagProfileTest.php
@@ -365,6 +365,11 @@ public function testTagManifestAllowed(): void
         $this->assertArrayEquals(["md5"], $profile->getTagManifestsAllowed());
     }
 
+    /**
+     * @group Profiles
+     * @covers ::setTagFilesAllowed
+     * @covers ::getTagFilesRequired
+     */
     public function testTagFilesMissingFromAllowed(): void
     {
         $profileJson = <<< JSON
@@ -393,4 +398,92 @@ public function testTagFilesMissingFromAllowed(): void
         $profile = BagItProfile::fromJson($profileJson);
         $this->assertTrue($profile->isValid());
     }
+
+    /**
+     * @group Profiles
+     * @covers \whikloj\BagItTools\Bag::isValid
+     * @covers \whikloj\BagItTools\Bag::addBagProfileByJson
+     * @covers ::validateBag
+     */
+    public function testAddProfileToBag(): void
+    {
+        $profileJson = <<<JSON
+{
+  "BagIt-Profile-Info":{
+    "BagIt-Profile-Identifier":"http://example.profile.org/bagit-test-profile.json",
+    "BagIt-Profile-Version": "1.1.0",
+    "Source-Organization":"Example Organization",
+    "Contact-Name":"John D Smith",
+    "External-Description":"BagIt Profile for testing bag profiles",
+    "Version":"0.3"
+  },
+  "Bag-Info":{
+    "Bagging-Date":{
+      "required":true
+    },
+    "Source-Organization":{
+      "required":true,
+      "values":[
+        "Simon Fraser University",
+        "York University"
+      ]
+    },
+    "Contact-Phone":{
+      "required":true
+    }
+  },
+  "Manifests-Required":[
+    "md5"
+  ],
+  "Accept-Serialization":[
+    "application/zip"
+  ],
+  "Allow-Fetch.txt":false,
+  "Accept-BagIt-Version":[
+    "1.0",
+    "0.97"
+  ]
+}
+JSON;
+        $profile = BagItProfile::fromJson($profileJson);
+        $this->assertTrue($profile->isValid());
+        $bag = Bag::create($this->tmpdir);
+        $bag->addBagProfileByJson($profileJson);
+        $this->assertFalse($bag->isValid());
+        $bag->addBagInfoTag("Source-Organization", "Simon Fraser University");
+        $bag->addBagInfoTag("Contact-Phone", "555-555-5555");
+        $this->assertFalse($bag->isValid());
+        $this->assertCount(1, $bag->getErrors());
+        $error = $bag->getErrors()[0];
+        $this->assertEquals(
+            [
+                "file" => "http://example.profile.org/bagit-test-profile.json",
+                "message" => "Profile requires payload manifest(s) which are missing from the bag (md5)"
+            ],
+            $error
+        );
+        $bag->setAlgorithm("md5");
+        $this->assertTrue($bag->isValid());
+    }
+
+    /**
+     * @group Profiles
+     * @covers \whikloj\BagItTools\Bag::addBagProfileByJson
+     * @covers \whikloj\BagItTools\Bag::addBagProfileInternal
+     * @covers \whikloj\BagItTools\Bag::removeBagProfile
+     */
+    public function testAddSameProfileTwice(): void
+    {
+        $profileJson = file_get_contents(self::$profiles . "/bagProfileFoo.json");
+        $bag = Bag::create($this->tmpdir);
+        $this->assertCount(0, $bag->getBagProfiles());
+        $bag->addBagProfileByJson($profileJson);
+        $this->assertCount(1, $bag->getBagProfiles());
+        $bag->addBagProfileByJson($profileJson);
+        $this->assertCount(1, $bag->getBagProfiles());
+        $bag->removeBagProfile("http://some.incorrect.identifier");
+        $this->assertCount(1, $bag->getBagProfiles());
+        $bag->removeBagProfile("http://www.library.yale.edu/mssa/bagitprofiles/disk_images.json");
+        $this->assertCount(0, $bag->getBagProfiles());
+    }
 }
diff --git a/tests/Profiles/ProfileWebTests.php b/tests/Profiles/ProfileWebTests.php
new file mode 100644
index 0000000..6167207
--- /dev/null
+++ b/tests/Profiles/ProfileWebTests.php
@@ -0,0 +1,103 @@
+<?php
+
+namespace whikloj\BagItTools\Test\Profiles;
+
+use whikloj\BagItTools\Bag;
+use whikloj\BagItTools\Profiles\BagItProfile;
+use whikloj\BagItTools\Profiles\ProfileFactory;
+use whikloj\BagItTools\Test\BagItWebserverFramework;
+
+class ProfileWebTests extends BagItWebserverFramework
+{
+    public static function setUpBeforeClass(): void
+    {
+        $profileJson = <<<JSON
+{
+  "BagIt-Profile-Info":{
+    "BagIt-Profile-Identifier":"http://example.profile.org/bagit-test-profile.json",
+    "BagIt-Profile-Version": "1.1.0",
+    "Source-Organization":"Example Organization",
+    "Contact-Name":"John D Smith",
+    "External-Description":"BagIt Profile for testing bag profiles",
+    "Version":"0.3"
+  },
+  "Bag-Info":{
+    "Bagging-Date":{
+      "required":true
+    },
+    "Source-Organization":{
+      "required":true,
+      "values":[
+        "Simon Fraser University",
+        "York University"
+      ]
+    },
+    "Contact-Phone":{
+      "required":true
+    }
+  },
+  "Manifests-Required":[
+    "md5"
+  ],
+  "Accept-Serialization":[
+    "application/zip"
+  ],
+  "Allow-Fetch.txt":false,
+  "Accept-BagIt-Version":[
+    "1.0",
+    "0.97"
+  ]
+}
+JSON;
+        self::$webserver_files = [
+            'profile1.json' => [
+                'content' => $profileJson,
+                'path' => 'bagit-test-profile.json',
+            ],
+        ];
+        parent::setUpBeforeClass();
+    }
+
+    public function testAddProfileToBagUri(): void
+    {
+        $profile = ProfileFactory::generateProfileFromUri(self::$remote_urls[0]);
+        $this->assertTrue($profile->isValid());
+        $bag = Bag::create($this->tmpdir);
+        $bag->addBagProfileByURL(self::$remote_urls[0]);
+        $this->assertFalse($bag->isValid());
+        $bag->addBagInfoTag("Source-Organization", "Simon Fraser University");
+        $bag->addBagInfoTag("Contact-Phone", "555-555-5555");
+        $this->assertFalse($bag->isValid());
+        $this->assertCount(1, $bag->getErrors());
+        $error = $bag->getErrors()[0];
+        $this->assertEquals(
+            [
+                "file" => "http://example.profile.org/bagit-test-profile.json",
+                "message" => "Profile requires payload manifest(s) which are missing from the bag (md5)"
+            ],
+            $error
+        );
+        $bag->setAlgorithm("md5");
+        $this->assertTrue($bag->isValid());
+    }
+
+    /**
+     * @group Profiles
+     * @covers \whikloj\BagItTools\Bag::addBagProfileByJson
+     * @covers \whikloj\BagItTools\Bag::addBagProfileInternal
+     * @covers \whikloj\BagItTools\Bag::removeBagProfile
+     */
+    public function testAddSameProfileTwiceByUri(): void
+    {
+        $bag = Bag::create($this->tmpdir);
+        $this->assertCount(0, $bag->getBagProfiles());
+        $bag->addBagProfileByURL(self::$remote_urls[0]);
+        $this->assertCount(1, $bag->getBagProfiles());
+        $bag->addBagProfileByURL(self::$remote_urls[0]);
+        $this->assertCount(1, $bag->getBagProfiles());
+        $bag->removeBagProfile("http://some.incorrect.identifier");
+        $this->assertCount(1, $bag->getBagProfiles());
+        $bag->removeBagProfile("http://www.library.yale.edu/mssa/bagitprofiles/disk_images.json");
+        $this->assertCount(0, $bag->getBagProfiles());
+    }
+}