diff --git a/inc/version-check/namespace.php b/inc/version-check/namespace.php
index f8379f35..090a53c9 100644
--- a/inc/version-check/namespace.php
+++ b/inc/version-check/namespace.php
@@ -87,23 +87,27 @@ function get_browser_check_response( string $agent ) {
 	// Switch delimiter to avoid conflicts.
 	$regex = '#' . trim( BROWSER_REGEX, '/' ) . '#';
 	$supported = preg_match( $regex, $agent, $matches );
+	$data = parse_user_agent( $agent );
+
+	$default_data = [
+		'platform'        => _x( 'your platform', 'operating system check', 'fair' ),
+		'name'            => _x( 'your browser', 'browser version check', 'fair' ),
+		'version'         => '',
+		'current_version' => '',
+		'upgrade'         => ! $supported,
+		'insecure'        => ! $supported,
+		'update_url'      => 'https://browsehappy.com/',
+		'img_src'         => '',
+		'img_src_ssl'     => '',
+	];
+	$data = array_merge( $default_data, $data );
 
 	return [
 		'response' => [
 			'code' => 200,
 			'message' => 'OK',
 		],
-		'body' => json_encode( [
-			'platform' => _x( 'your platform', 'operating system check', 'fair' ),
-			'name' => _x( 'your browser', 'browser version check', 'fair' ),
-			'version' => '',
-			'current_version' => '',
-			'upgrade' => ! $supported,
-			'insecure' => ! $supported,
-			'update_url' => 'https://browsehappy.com/',
-			'img_src' => '',
-			'img_src_ssl' => '',
-		] ),
+		'body' => json_encode( $data ),
 		'headers' => [],
 		'cookies' => [],
 		'http_response_code' => 200,
@@ -262,3 +266,447 @@ function get_server_check_response( string $version ) {
 		'http_response_code' => 200,
 	];
 }
+
+/**
+ * Returns current version numbers for all browsers.
+ *
+ * These are for major release branches, not full build numbers.
+ * Firefox 3.6, 4, etc., not Chrome 11.0.696.65.
+ *
+ * @return array Associative array of browser names with their respective
+ *               current (or somewhat current) version number.
+ */
+function get_browser_current_versions() {
+	return [
+		'Chrome'            => '18', // Lowest version at the moment (mobile).
+		'Firefox'           => '56',
+		'Microsoft Edge'    => '15.15063',
+		'Opera'             => '12.18',
+		'Safari'            => '11',
+		'Internet Explorer' => '11',
+	];
+}
+
+/**
+ * Returns browser data for a given browser.
+ *
+ * @param string|false $browser The name of the browser. Default false.
+ * @return false|array|object {
+ *     Array of data objects about browsers. False if the browser is unknown.
+ *
+ *     @type string    $name        Name of the browser.
+ *     @type string    $url         The home URL for the browser.
+ *     @type string    $img_src     The non-HTTPs URL for the browser's logo image.
+ *     @type string    $img_src_ssl The HTTPS URL for the browser's logo image.
+ * }
+ */
+function get_browser_data( $browser = false ) {
+
+	$data = [
+		'Internet Explorer' => (object) [
+			'name'        => 'Internet Explorer',
+			'url'         => 'https://support.microsoft.com/help/17621/internet-explorer-downloads',
+		],
+		'Edge' => (object) [
+			'name'        => 'Microsoft Edge',
+			'url'         => 'https://www.microsoft.com/edge',
+		],
+		'Firefox' => (object) [
+			'name'        => 'Mozilla Firefox',
+			'url'         => 'https://www.mozilla.org/firefox/',
+		],
+		'Safari' => (object) [
+			'name'        => 'Safari',
+			'url'         => 'https://www.apple.com/safari/',
+		],
+		'Opera' => (object) [
+			'name'        => 'Opera',
+			'url'         => 'https://www.opera.com/',
+		],
+		'Chrome' => (object) [
+			'name'        => 'Google Chrome',
+			'url'         => 'https://www.google.com/chrome',
+		],
+	];
+
+	if ( false === $browser ) {
+		return $data;
+	}
+
+	if ( ! isset( $data[ $browser ] ) ) {
+		return false;
+	}
+
+	return $data[ $browser ];
+}
+
+/**
+ * Returns an associative array of explicit browser token names and their
+ * associated info.
+ *
+ * Explicit tokens are tokens that, if present, indicate a specific browser.
+ *
+ * If a browser is not identified by an explicit token, or s special
+ * handling not supported by the default handler, then a new conditional block
+ * for the browser instead needs to be added in parse_user_agent().
+ *
+ * In any case, the browser token name also needs to be added to the regex for
+ * browser tokens in parse_user_agent().
+ *
+ * @return array {
+ *     Associative array of browser tokens and their associated data.
+ *
+ *     @type array $data {
+ *         Associative array of browser data. All are optional.
+ *
+ *         @type string $name        Name of browser, if it differs from the
+ *                                   token name. Default is token name.
+ *         @type bool   $use_version Should the 'Version' token, if present,
+ *                                   supercede the version associated with the
+ *                                   browser token? Default false.
+ *         @type bool   $mobile      Does the browser signify the platform is
+ *                                   mobile (for situations where it may no
+ *                                   already be apparent)? Default false.
+ *         @type string $platform    The name of the platform, to supercede
+ *                                   whatever platform may have been detected.
+ *                                   Default empty string.
+ *     }
+ * }
+ */
+function get_explicit_browser_tokens() {
+	return [
+		'Camino'         => [],
+		'Chromium'       => [],
+		'Edge'           => [
+			'name' => 'Microsoft Edge',
+		],
+		'Kindle'         => [
+			'name'        => 'Kindle Browser',
+			'use_version' => true,
+		],
+		'Konqueror'      => [],
+		'konqueror'      => [
+			'name' => 'Konqueror',
+		],
+		'NokiaBrowser'   => [
+			'name'   => 'Nokia Browser',
+			'mobile' => true,
+		],
+		'Opera Mini'     => [ // Must be before 'Opera'.
+			'mobile'      => true,
+			'use_version' => true,
+		],
+		'Opera'          => [
+			'use_version' => true,
+		],
+		'OPR'            => [
+			'name'        => 'Opera',
+			'use_version' => true,
+		],
+		'PaleMoon'       => [
+			'name' => 'Pale Moon',
+		],
+		'QQBrowser'      => [
+			'name' => 'QQ Browser',
+		],
+		'RockMelt'       => [],
+		'SamsungBrowser' => [
+			'name' => 'Samsung Browser',
+		],
+		'SeaMonkey'      => [],
+		'Silk'           => [
+			'name' => 'Amazon Silk',
+		],
+		'S40OviBrowser'  => [
+			'name'     => 'Ovi Browser',
+			'mobile'   => true,
+			'platform' => 'Symbian',
+		],
+		'UCBrowser'      => [ // Must be before 'UCWEB'.
+			'name' => 'UC Browser',
+		],
+		'UCWEB'          => [
+			'name' => 'UC Browser',
+		],
+		'Vivaldi'        => [],
+		'IEMobile'       => [ // Keep last just in case.
+			'name' => 'Internet Explorer Mobile',
+		],
+	];
+}
+
+/**
+ * Parses a user agent string into its important parts.
+ *
+ * @param string $user_agent The user agent string for a browser.
+ * @return array {
+ *     Array containing data based on the parsing of the user agent.
+ *
+ *     @type string $platform        The platform running the browser.
+ *     @type string $name            The name of the browser.
+ *     @type string $version         The reported version of the browser.
+ *     @type string $update_url      The URL to obtain the update for the browser.
+ *     @type string $img_src         The non-HTTPS URL for the browser's logo image.
+ *     @type string $img_src_ssl     The HTTPS URL for the browser's logo image.
+ *     @type string $current_version The current latest version of the browser.
+ *     @type bool   $upgrade         Is there an update available for the browser?
+ *     @type bool   $insecure        Is the browser insecure?
+ *     @type bool   $mobile          Is the browser on a mobile platform?
+ * }
+ */
+function parse_user_agent( $user_agent ) {
+	$data = [
+		'name'            => '',
+		'version'         => '',
+		'platform'        => '',
+		'update_url'      => '',
+		'img_src'         => '',
+		'img_src_ssl'     => '',
+		'current_version' => '',
+		'upgrade'         => false,
+		'insecure'        => false,
+		'mobile'          => false,
+	];
+	$mobile_device = '';
+
+	/**
+	 * Identify platform/OS in user-agent string.
+	 * '/(?P<platform>'                                      // Capture subpattern matches into 'platform' array.
+	 * . 'Windows Phone( OS)?|Symbian|SymbOS|Android|iPhone' // Platform tokens.
+	 * . '|iPad|Windows|Linux|Macintosh|FreeBSD|OpenBSD'     // More platform tokens.
+	 * . '|SunOS|RIM Tablet OS|PlayBook'                     // More platform tokens.
+	 * . ')'
+	 * . '(?:'
+	 * . ' (NT|amd64|armv7l|zvav)'                           // Possibly followed by specific modifiers/specifiers.
+	 * . ')*'
+	 * . '(?:'
+	 * . ' [ix]?[0-9._]+'                                    // Possibly followed by architecture modifier (e.g. x86_64).
+	 * . '(\-[0-9a-z\.\-]+)?'                                // Possibly followed by a hypenated version number.
+	 * . ')*'
+	 * . '(;|\))'                                            // Ending in a semi-colon or close parenthesis.
+	 * . '/im',                                              // Case insensitive, multiline.
+	 */
+	if ( preg_match(
+		'/(?P<platform>Windows Phone( OS)?|Symbian|SymbOS|Android|iPhone|iPad|Windows|Linux|Macintosh|FreeBSD|OpenBSD|SunOS|RIM Tablet OS|PlayBook)(?: (NT|amd64|armv7l|zvav))*(?: [ix]?[0-9._]+(\-[0-9a-z\.\-]+)?)*(;|\))/im',
+		$user_agent,
+		$regs
+	) ) {
+		$data['platform'] = $regs['platform'];
+	}
+
+	/**
+	 * Find tokens of interest in user-agent string.
+	 *
+	 * '%(?P<name>'                                              // Capture subpattern matches into the 'name' array.
+	 * .     'Opera Mini|Opera|OPR|Edge|UCBrowser|UCWEB'         // Browser tokens.
+	 * .     '|QQBrowser|SymbianOS|Symbian|S40OviBrowser'        // More browser tokens.
+	 * .     '|Trident|Silk|Konqueror|PaleMoon|Puffin'           // More browser tokens.
+	 * .     '|SeaMonkey|Vivaldi|Camino|Chromium|Kindle|Firefox' // More browser tokens.
+	 * .     '|SamsungBrowser|(?:Mobile )?Safari|NokiaBrowser'   // More browser tokens.
+	 * .     '|MSIE|RockMelt|AppleWebKit|Chrome|IEMobile'        // More browser tokens.
+	 * .     '|Version'                                          // Version token.
+	 * . ')'
+	 * . '(?:'
+	 * .     '[/ ]'                                              // Forward slash or space.
+	 * . ')'
+	 * . '(?P<version>'                                          // Capture subpattern matches into 'version' array.
+	 * .     '[0-9.]+'                                           // One or more numbers and/or decimal points.
+	 * . ')'
+	 * . '%im',                                                  // Case insensitive, multiline.
+	 */
+	preg_match_all(
+		'%(?P<name>Opera Mini|Opera|OPR|Edge|UCBrowser|UCWEB|QQBrowser|SymbianOS|Symbian|S40OviBrowser|Trident|Silk|Konqueror|PaleMoon|Puffin|SeaMonkey|Vivaldi|Camino|Chromium|Kindle|Firefox|SamsungBrowser|(?:Mobile )?Safari|NokiaBrowser|MSIE|RockMelt|AppleWebKit|Chrome|IEMobile|Version)(?:[/ ])(?P<version>[0-9.]+)%im',
+		$user_agent,
+		$result,
+		PREG_PATTERN_ORDER
+	);
+
+	// Create associative array with tokens as keys and versions as values.
+	$tokens = array_combine( array_reverse( $result['name'] ), array_reverse( $result['version'] ) );
+
+	// Properly set platform if Android is actually being reported.
+	if ( 'Linux' === $data['platform'] && false !== strpos( $user_agent, 'Android' ) ) {
+		if ( strpos( $user_agent, 'Kindle' ) ) {
+			$data['platform'] = 'Fire OS';
+		} else {
+			$data['platform'] = 'Android';
+		}
+	} elseif ( 'Windows Phone' === $data['platform'] ) {
+		// Normalize Windows Phone OS name when "OS" is omitted.
+		$data['platform'] = 'Windows Phone OS';
+	} elseif ( in_array( $data['platform'], [ 'Symbian', 'SymbOS' ] ) || ! empty( $tokens['SymbianOS'] ) || ! empty( $tokens['Symbian'] ) ) {
+		// Standardize Symbian OS name.
+		if ( ! in_array( $data['platform'], [ 'Symbian', 'SymbOS' ] ) ) {
+			unset( $tokens['SymbianOS'] );
+			unset( $tokens['Symbian'] );
+		}
+		$data['platform'] = 'Symbian';
+	} elseif ( ! $data['platform'] && preg_match( '/BlackBerry|Nokia|SonyEricsson/', $user_agent, $matches ) ) {
+		// Generically detect some mobile devices.
+		$data['platform'] = 'Mobile';
+		$mobile_device    = $matches[0];
+	}
+
+	// Flag known mobile platforms as mobile.
+	if ( in_array( $data['platform'], [ 'Android', 'Fire OS', 'iPad', 'iPhone', 'Mobile', 'PlayBook', 'RIM Tablet OS', 'Symbian', 'Windows Phone OS' ] ) ) {
+		$data['mobile'] = true;
+	}
+
+	// If Version/x.x.x was specified in UA string store it and ignore it.
+	if ( ! empty( $tokens['Version'] ) ) {
+		$version = $tokens['Version'];
+		unset( $tokens['Version'] );
+	}
+
+	$explicit_tokens = get_explicit_browser_tokens();
+
+	// No indentifiers provided.
+	if ( ! $tokens ) {
+		if ( 'BlackBerry' === $mobile_device ) {
+			$data['name'] = 'BlackBerry Browser';
+		} else {
+			$data['name'] = 'unknown';
+		}
+	} elseif ( $found = array_intersect( array_keys( $explicit_tokens ), array_keys( $tokens ) ) ) { // phpcs:ignore Squiz.PHP.DisallowMultipleAssignments.FoundInControlStructure
+		// Explicitly identified browser (info defined above in $explicit_tokens).
+		$token = reset( $found );
+
+		$data['name']    = $explicit_tokens[ $token ]['name'] ?? $token;
+		$data['version'] = $tokens[ $token ];
+		if ( empty( $explicit_tokens[ $token ]['use_version'] ) ) {
+			$version = '';
+		}
+		if ( ! empty( $explicit_tokens[ $token ]['mobile'] ) ) {
+			$data['mobile'] = true;
+		}
+		if ( ! empty( $explicit_tokens[ $token ]['platform'] ) ) {
+			$data['platform'] = $explicit_tokens[ $token ]['platform'];
+		}
+	} elseif ( ! empty( $tokens['Puffin'] ) ) {
+		// Puffin.
+		$data['name']     = 'Puffin';
+		$data['version']  = $tokens['Puffin'];
+		$version          = '';
+		// If not an already-identified mobile platform, set it as such.
+		if ( ! $data['mobile'] ) {
+			$data['mobile']   = true;
+			$data['platform'] = '';
+		}
+	} elseif ( ! empty( $tokens['Trident'] ) ) {
+		// Trident (Internet Explorer).
+		// IE 8-10 more reliably report version via Trident token than MSIE token.
+		// IE 11 uses Trident token without an MSIE token.
+		// https://msdn.microsoft.com/library/hh869301(v=vs.85).aspx.
+		$data['name'] = 'Internet Explorer';
+		$trident_ie_mapping = [
+			'4.0' => '8.0',
+			'5.0' => '9.0',
+			'6.0' => '10.0',
+			'7.0' => '11.0',
+		];
+		$ver = $tokens['Trident'];
+		$data['version'] = $trident_ie_mapping[ $ver ] ?? $ver;
+	} elseif ( ! empty( $tokens['MSIE'] ) ) {
+		// Internet Explorer (pre v8.0).
+		$data['name'] = 'Internet Explorer';
+		$data['version'] = $tokens['MSIE'];
+	} elseif ( ! empty( $tokens['AppleWebKit'] ) ) {
+		// AppleWebKit-emulating browsers.
+		if ( ! empty( $tokens['Mobile Safari'] ) ) {
+			if ( ! empty( $tokens['Chrome'] ) ) {
+				$data['name'] = 'Chrome';
+				$version = $tokens['Chrome'];
+			} elseif ( 'Android' === $data['platform'] ) {
+				$data['name'] = 'Android Browser';
+			} elseif ( 'Fire OS' === $data['platform'] ) {
+				$data['name'] = 'Kindle Browser';
+			} elseif ( false !== strpos( $user_agent, 'BlackBerry' ) || false !== strpos( $user_agent, 'BB10' ) ) {
+				$data['name']   = 'BlackBerry Browser';
+				$data['mobile'] = true;
+
+				if ( false !== stripos( $user_agent, 'BB10' ) ) {
+					$tokens['Mobile Safari'] = '';
+					$version = '';
+				}
+			} else {
+				$data['name'] = 'Mobile Safari';
+			}
+		} elseif ( ! empty( $tokens['Chrome'] ) ) {
+			$data['name'] = 'Chrome';
+			$version = '';
+		} elseif ( ! empty( $data['platform'] ) && 'PlayBook' == $data['platform'] ) {
+			$data['name'] = 'PlayBook';
+		} elseif ( ! empty( $tokens['Safari'] ) ) {
+			if ( 'Android' === $data['platform'] ) {
+				$data['name'] = 'Android Browser';
+			} elseif ( 'Symbian' === $data['platform'] ) {
+				$data['name'] = 'Nokia Browser';
+				$tokens['Safari'] = '';
+			} else {
+				$data['name'] = 'Safari';
+			}
+		} else {
+			$data['name'] = 'unknown';
+			$tokens['AppleWebKit'] = '';
+			$version = '';
+		}
+		$data['version'] = $tokens[ $data['name'] ] ?? '';
+	} else {
+		// Fall back to whatever is being reported.
+		$ordered_tokens = array_reverse( $tokens );
+		$data['version'] = reset( $ordered_tokens );
+		$data['name'] = key( $ordered_tokens );
+	}
+
+	// Set the platform for Amazon-related browsers.
+	if ( in_array( $data['name'], [ 'Amazon Silk', 'Kindle Browser' ] ) ) {
+		$data['platform'] = 'Fire OS';
+		$data['mobile']   = true;
+	}
+
+	// If Version/x.x.x was specified in UA string.
+	if ( ! empty( $version ) ) {
+		$data['version'] = $version;
+	}
+
+	if ( $data['mobile'] ) {
+		// Generically set "Mobile" as the platform if a platform hasn't been set.
+		if ( ! $data['platform'] ) {
+			$data['platform'] = 'Mobile';
+		}
+
+		// Don't fetch additional browser data for mobile platform browsers at this time.
+		return $data;
+	}
+
+	$browser_data            = get_browser_data( $data['name'] );
+	$data['update_url']      = $browser_data ? $browser_data->url : '';
+	$data['current_version'] = get_browser_version_from_name( $data['name'] );
+	$data['upgrade']         = ( ! empty( $data['current_version'] ) && version_compare( $data['version'], $data['current_version'], '<' ) );
+
+	if ( 'Internet Explorer' === $data['name'] ) {
+		$data['insecure'] = true;
+		$data['upgrade']  = true;
+	} elseif ( 'Firefox' === $data['name'] && version_compare( $data['version'], '52', '<' ) ) {
+		$data['insecure'] = true;
+	} elseif ( 'Opera' === $data['name'] && version_compare( $data['version'], '12.18', '<' ) ) {
+		$data['insecure'] = true;
+	} elseif ( 'Safari' === $data['name'] && version_compare( $data['version'], '10', '<' ) ) {
+		$data['insecure'] = true;
+	}
+
+	return $data;
+}
+
+/**
+ * Returns the current version for the given browser.
+ *
+ * @param string $name The name of the browser.
+ * @return string      The version for the browser or an empty string if an
+ *                     unknown browser.
+ */
+function get_browser_version_from_name( $name ) {
+	$versions = get_browser_current_versions();
+
+	return isset( $versions[ $name ] ) ? $versions[ $name ] : '';
+}