diff --git a/ParserKrokiTag.php b/ParserKrokiTag.php
new file mode 100644
index 0000000..4405464
--- /dev/null
+++ b/ParserKrokiTag.php
@@ -0,0 +1,366 @@
+<?php
+namespace MediaWiki\Kroki;
+
+use LocalRepo;
+use MediaWiki\Html\Html;
+use MediaWiki\MediaWikiServices;
+use MediaWiki\Page\PageReference;
+use OutputPage;
+use Parser;
+use ParserOptions;
+use ParserOutput;
+use PPFrame;
+use Status;
+
+/**
+ * Class ParserKrokiTag
+ *
+ * This class represents a parser tag for handling Kroki tags.
+ */
+class ParserKrokiTag {
+	/**
+	 * The CSS class used for styling Kroki diagrams in the application.
+	 *
+	 * @var string KROKI_CSS_CLASS
+	 */
+	private const KROKI_CSS_CLASS = 'mw-kroki';
+	private \ParserOptions $parserOptions;
+	private \ParserOutput $parserOutput;
+	private \Language $language;
+
+	/** @var string[] Diagram types */
+	public const DIAGRAM_TYPES = [
+		'blockdiag',
+		'bpmn',
+		'bytefield',
+		'seqdiag',
+		'actdiag',
+		'nwdiag',
+		'packetdiag',
+		'rackdiag',
+		'c4plantuml',
+		'd2',
+		'dbml',
+		'ditaa',
+		'erd',
+		'excalidraw',
+		'graphviz',
+		'mermaid',
+		'nomnoml',
+		'pikchr',
+		'plantuml',
+		'structurizr',
+		'svgbob',
+		'symbolator',
+		'tikz',
+		'vega',
+		'vegalite',
+		'wavedrom',
+		'wireviz'
+	];
+
+	/**
+	 * Constructor method for MyClass.
+	 *
+	 * @param Parser $parser The parser object.
+	 * @param ParserOptions $parserOptions The parser options object.
+	 * @param ParserOutput $parserOutput The parser output object.
+	 * @return void
+	 */
+	public function __construct( Parser $parser, \ParserOptions $parserOptions, \ParserOutput $parserOutput ) {
+		$this->parserOptions = $parserOptions;
+		$this->parserOutput = $parserOutput;
+		$this->language = $parser->getTargetLanguage();
+	}
+
+	/**
+	 * Check if $string is one of the available diagram types.
+	 *
+	 * @param string $string
+	 * @return bool
+	 */
+	private static function validDiagrammType( string $string ): bool {
+		return in_array( strtolower( $string ), array_map( 'strtolower', self::DIAGRAM_TYPES ), true );
+	}
+
+	/**
+	 * - Add tracking categories
+	 * - Split parser cache for preview, where Graph uses different HTML
+	 * @param ParserOutput $parserOutput
+	 * @param ?PageReference $pageRef
+	 * @param bool $isPreview
+	 */
+	public static function addTagMetadata(
+		ParserOutput $parserOutput, ?PageReference $pageRef, bool $isPreview
+	): void {
+		$tc = MediaWikiServices::getInstance()->getTrackingCategories();
+		if ( $parserOutput->getExtensionData( 'kroki_diagram_broken' ) ) {
+			$tc->addTrackingCategory( $parserOutput, 'kroki-diagram-broken-category', $pageRef );
+		}
+		$tc->addTrackingCategory( $parserOutput, 'kroki-diagram-tracking-category', $pageRef );
+
+		if ( $isPreview ) {
+			$parserOutput->updateCacheExpiry( 0 );
+		}
+	}
+
+	/**
+	 * Handles the onKrokiTag hook.
+	 *
+	 * @param string|null $input The input string for the tag.
+	 * @param array $args An array of arguments passed to the tag.
+	 * @param Parser $parser The Parser object for the current page.
+	 * @param PPFrame $frame The PPFrame object for the current page.
+	 * @return Status|string The generated HTML or a Status object if there was an error.
+	 */
+	public static function onKrokiTag( $input, $args, $parser, $frame ) {
+		$tag = new self( $parser, $parser->getOptions(), $parser->getOutput() );
+
+		$input = $parser->getStripState()->unstripNoWiki( $input ?? '' );
+
+		$html = $tag->buildHtmlInline( (string)$input, $args );
+		self::addTagMetadata( $parser->getOutput(), $parser->getPage(), $parser->getOptions()->getIsPreview() );
+		return $html;
+	}
+
+	/**
+	 * Returns the kroki.io server url
+	 *
+	 * @return string
+	 */
+	private static function getKrokiUrl(): string {
+		return MediaWikiServices::getInstance()->getMainConfig()->get( 'KrokiServerEndpoint' );
+	}
+
+	/**
+	 * Formats the HTML for displaying an error message.
+	 *
+	 * @param \Message $wfMessage The error message to be displayed.
+	 * @param string $data_string The data string associated with the error (optional).
+	 * @param string $response_string The response string associated with the error (optional).
+	 * @return string The formatted HTML code for the error message.
+	 */
+	private function formatError( \Message $wfMessage, string $data_string = '', string $response_string = '' ): string {
+		$this->parserOutput->setExtensionData( 'kroki_diagram_broken', true );
+		$error = $wfMessage->inLanguage( $this->language )->parse();
+
+		if ( !empty( $response_string ) ) {
+			$contents = ( '<strong>HTTP-Response:</strong> ' . PHP_EOL .
+					$response_string . PHP_EOL . PHP_EOL )
+				. '<strong>Diagram-Code:</strong>' . $data_string;
+		} else {
+			$contents = '<strong>Diagram-Code:</strong>' . $data_string;
+		}
+
+		return Html::rawElement(
+			'div',
+			[ 'class' => self::KROKI_CSS_CLASS ],
+			Html::rawElement(
+				'pre',
+				[
+					'data-title' => $error,
+				],
+				$contents
+			)
+		);
+	}
+
+	/**
+	 * Generates the HTML for the 'buildHtml_inline' method.
+	 *
+	 * @param string $input The input string for the tag.
+	 * @param null $args An array of arguments passed to the tag.
+	 * @return string The generated HTML or a Status object if there was an error.
+	 */
+	public function buildHtmlInline( string $input, $args = null ): string {
+		if ( $input === '' ) {
+			return $this->formatError( wfMessage( 'kroki-error-empty-input' ) );
+		}
+
+		$lang = $args['lang'] ?? '';
+
+		// For invalid diagram type, output nothing instead of broken img.
+		if ( !self::validDiagrammType( $lang ) ) {
+			return $this->formatError( wfMessage( 'kroki-error-unknown-language' ) );
+		}
+		
+		$output_format = $args['output_format'] ?? 'svg';
+		
+		//TODO: add check for format onlt png or svg
+		
+		//DEBUG
+		echo $output_format;
+
+		// set post fields
+		$requestParams = [
+			'method' => 'POST',
+			'postData' => json_encode( [
+				'diagram_source' => $input,
+				'diagram_type' => $lang,
+				'output_format' => $output_format,
+				'diagram_options' => [
+					'no-doctype' => 'TRUE'
+				] ] ),
+		];
+
+		$url = self::getKrokiUrl();
+
+		// Create HttpRequest
+		$request = MediaWikiServices::getInstance()->getHttpRequestFactory()->create( $url, $requestParams, __METHOD__ );
+
+		// Send the request
+		$status = $request->execute();
+
+		if ( !$status->isOK() ) {
+			return $this->formatError( wfMessage( 'kroki-error-diagram-render-failed' ), $input, $request->getContent() );
+		}
+
+		if ( $request->getContent() === '' ) {
+			return $this->formatError( wfMessage( 'kroki-error-diagram-render-failed' ), $input );
+		}
+
+		$width = $args['width'] ?? '';
+		$height = $args['height'] ?? '';
+
+		return self::formatHtml( "data:image/" . $output_format . "+xml;base64," . base64_encode( $request->getContent() ), $width, $height, $lang );
+	}
+
+	/**
+	 * Builds the HTML for a local file diagram.
+	 *
+	 * @param string $input The input string for the diagram.
+	 * @param null $args An array of additional arguments passed to the diagram.
+	 * @return Status|string The generated HTML or a Status object if there was an error.
+	 * @throws \MWException
+	 */
+	public function buildHtmlLocalfile( string $input, $args = null ) {
+		if ( $input === '' ) {
+			return $this->formatError( wfMessage( 'kroki-error-empty-input' ) );
+		}
+
+		$lang = $args['lang'] ?? '';
+
+		// For invalid diagram type, output nothing instead of broken img.
+		if ( !self::validDiagrammType( $lang ) ) {
+			return $this->formatError( wfMessage( 'kroki-error-unknown-language' ) );
+		}
+		
+		$output_format = $args['output_format'] ?? 'svg';
+		
+		//TODO: add check for format onlt png or svg
+		
+		//DEBUG
+		echo $output_format;
+
+		// set post fields
+		$requestParams = [
+			'method' => 'POST',
+			'postData' => json_encode( [
+				'diagram_source' => $input,
+				'diagram_type' => $lang,
+				'output_format' => $output_format,
+				'diagram_options' => [
+					'no-doctype' => 'TRUE'
+				] ], JSON_FORCE_OBJECT ),
+		];
+
+		$url = self::getKrokiUrl();
+
+		// Create HttpRequest
+		$request = MediaWikiServices::getInstance()->getHttpRequestFactory()->create( $url, $requestParams, __METHOD__ );
+
+		// Send the request
+		$status = $request->execute();
+
+		if ( !$status->isOK() ) {
+			return $this->formatError( wfMessage( 'kroki-error-diagram-render-failed' ), $input, $request->getContent() );
+		}
+
+		if ( $request->getContent() === '' ) {
+			return $this->formatError( wfMessage( 'kroki-error-diagram-render-failed' ), $input );
+		}
+
+		$result = $request->getContent();
+
+		$localRepo = MediaWikiServices::getInstance()->getRepoGroup()->getLocalRepo();
+		$diagramsRepo = new LocalRepo( [
+			'class' => 'LocalRepo',
+			'name' => 'local',
+			'backend' => $localRepo->getBackend(),
+			'directory' => $localRepo->getZonePath( 'public' ) . '/kroki_diagrams',
+			'url' => $localRepo->getZoneUrl( 'public' ) . '/kroki_diagrams',
+			'hashLevels' => 0,
+			'thumbUrl' => '',
+			'transformVia404' => false,
+			'deletedDir' => '',
+			'deletedHashLevels' => 0,
+			'zones' => [
+				'public' => [
+					'directory' => '/kroki_diagrams',
+				],
+			],
+		] );
+
+		$sha1Input = sha1( $input );
+		$fileName = implode( '_', [ 'Kroki', $lang, $sha1Input ] ) . '.' . $output_format;
+		$graphFile = $diagramsRepo->findFile( $fileName );
+
+		if ( !$graphFile ) {
+			$graphFile = $diagramsRepo->newFile( $fileName );
+		}
+
+		if ( $graphFile->exists() ) {
+			$width = $args['width'] ?? '';
+			$height = $args['height'] ?? '';
+		
+			return self::formatHtml( $graphFile->getUrl(), $width, $height, $lang );
+		}
+
+		$tmpFactory = MediaWikiServices::getInstance()->getTempFSFileFactory();
+		$tmpGraphSourceFile = $tmpFactory->newTempFSFile( 'diagrams_out', $sha1Input );
+		file_put_contents( $tmpGraphSourceFile->getPath(), $result );
+
+		if ( $this->parserOptions->getIsPreview() ) {
+			$check = $diagramsRepo->storeTemp( $fileName, $tmpGraphSourceFile );
+		} else {
+			$check = $graphFile->publish( $tmpGraphSourceFile );
+		}
+
+		if ( !$check->isGood() ) {
+			$status->value = $this->formatError( $check->getHtml() );
+			return $status;
+		}
+
+		$width = $args['width'] ?? '';
+		$height = $args['height'] ?? '';
+		
+		return self::formatHtml( $graphFile->getUrl(), $width, $height, $lang );
+	}
+
+	/**
+	 * Formats the HTML for displaying an image.
+	 *
+	 * @param string $imgUrl The URL of the image.
+	 * @return string The formatted HTML code.
+	 */
+	private static function formatHtml( string $imgUrl, string $width, string $height, string $lang ): string {
+		return Html::rawElement(
+			'div',
+			[ 'class' => self::KROKI_CSS_CLASS ],
+			Html::element( 'img', [ 'src' => $imgUrl, 'width' => $width, 'height' => $height, 'style' => 'background-color: rgba(150, 150, 150, 0.5);' ] )
+		);
+	}
+
+	/**
+	 * Finalizes the parser output for the Kroki extension.
+	 *
+	 * @param OutputPage $outputPage The OutputPage object representing the rendered page.
+	 * @param ParserOutput $parserOutput The ParserOutput object for the current page.
+	 * @return void
+	 */
+	public static function finalizeParserOutput(
+		OutputPage $outputPage, ParserOutput $parserOutput
+	): void {
+		$outputPage->addModuleStyles( [ 'ext.kroki.styles' ] );
+	}
+}
\ No newline at end of file