diff --git a/lib/core/controllers/colored_text_editing_controller.dart b/lib/core/controllers/colored_text_editing_controller.dart
new file mode 100644
index 0000000..9aec67e
--- /dev/null
+++ b/lib/core/controllers/colored_text_editing_controller.dart
@@ -0,0 +1,107 @@
+import 'dart:developer';
+
+import 'package:flutter/gestures.dart';
+import 'package:flutter/material.dart';
+import 'package:languagetool_textfield/domain/mistake.dart';
+
+/// A TextEditingController with overrides buildTextSpan for building
+/// marked TextSpans with tap recognizer
+class ColoredTextEditingController extends TextEditingController {
+  /// List which contains Mistake objects spans are built from
+  List<Mistake> _mistakes = [];
+
+  final double _backGroundOpacity =
+  0.2; // background opacity for mistake TextSpan
+
+  final double _mistakeLineThickness =
+  1.5; // mistake TextSpan underline thickness
+
+  /// A method sets new list of Mistake and triggers buildTextSpan
+  void setMistakes(List<Mistake> list) {
+    _mistakes = list;
+    notifyListeners();
+  }
+
+  /// builds TextSpan from Mistake list
+  @override
+  TextSpan buildTextSpan({
+    required BuildContext context,
+    TextStyle? style,
+    required bool withComposing,
+  }) {
+    int currentOffset = 0; // enter index
+    final List<TextSpan> spans = []; // List of TextSpan
+    final int textLength = text.length; // Length of text to be built
+
+    /// Iterates _mistakes and adds TextSpans from Mistake offset and length
+    for (final Mistake mistake in _mistakes) {
+      /// Breaks the loop if iterated Mistake offset is bigger than text length.
+      if (mistake.offset > textLength ||
+          mistake.offset + mistake.length > textLength) {
+        break;
+      }
+
+      /// TextSpan before mistake
+      spans.add(
+        TextSpan(
+          text: text.substring(
+            currentOffset,
+            mistake.offset,
+          ),
+          style: style,
+        ),
+      );
+
+      /// Setting color of the mistake by its type
+      final Color mistakeColor = _getMistakeColor(mistake.type);
+
+      /// The mistake TextSpan
+      spans.add(
+        TextSpan(
+          text: text.substring(mistake.offset, mistake.offset + mistake.length),
+          mouseCursor: MaterialStateMouseCursor.clickable,
+          recognizer: TapGestureRecognizer()
+            ..onTapDown = _callOverlay, // calls overlay with mistakes details
+          style: style?.copyWith(
+            backgroundColor: mistakeColor.withOpacity(_backGroundOpacity),
+            decoration: TextDecoration.underline,
+            decorationColor: mistakeColor,
+            decorationThickness: _mistakeLineThickness,
+          ),
+        ),
+      );
+
+      /// Changing enter index position for the next iteration
+      currentOffset = mistake.offset + mistake.length;
+    }
+
+    /// TextSpan after mistake
+    spans.add(
+      TextSpan(
+        text: text.substring(currentOffset),
+        style: style,
+      ),
+    );
+
+    /// Returns TextSpan
+    return TextSpan(children: spans);
+  }
+
+  void _callOverlay(TapDownDetails details) {
+    log(details.globalPosition.toString());
+  }
+
+  /// Returns color for mistake TextSpan style
+  Color _getMistakeColor(String type) {
+    switch (type) {
+      case 'misspelling':
+        return Colors.red;
+      case 'style':
+        return Colors.blue;
+      case 'uncategorized':
+        return Colors.amber;
+      default:
+        return Colors.green;
+    }
+  }
+}
diff --git a/lib/domain/mistake.dart b/lib/domain/mistake.dart
index ecbd3a8..9433887 100644
--- a/lib/domain/mistake.dart
+++ b/lib/domain/mistake.dart
@@ -25,4 +25,10 @@ class Mistake {
     required this.length,
     this.replacements = const [],
   });
+
+  @override
+  String toString() {
+    return 'Mistake{message: $message, type: $type, offset: $offset, '
+        'length: $length, replacements: $replacements}';
+  }
 }
diff --git a/lib/implementations/debounce_lang_tool_service.dart b/lib/implementations/debounce_lang_tool_service.dart
index ed14755..7aabc2d 100644
--- a/lib/implementations/debounce_lang_tool_service.dart
+++ b/lib/implementations/debounce_lang_tool_service.dart
@@ -17,7 +17,11 @@ class DebounceLangToolService extends LanguageCheckService {
   ) : debouncing = Debouncing(duration: debouncingDuration);
 
   @override
-  Future<List<Mistake>> findMistakes(String text) =>
-      debouncing.debounce(() => baseService.findMistakes(text))
-          as Future<List<Mistake>>;
+  Future<List<Mistake>> findMistakes(String text) async {
+    final value = await debouncing.debounce(() {
+      return baseService.findMistakes(text);
+    }) as List<Mistake>?;
+
+    return value ?? [];
+  }
 }
diff --git a/lib/languagetool_textfield.dart b/lib/languagetool_textfield.dart
index abe7c4c..d3178aa 100644
--- a/lib/languagetool_textfield.dart
+++ b/lib/languagetool_textfield.dart
@@ -1 +1,10 @@
 library languagetool_textfield;
+
+export 'package:language_tool/language_tool.dart';
+
+export 'domain/language_check_service.dart';
+export 'domain/mistake.dart';
+export 'implementations/debounce_lang_tool_service.dart';
+export 'implementations/lang_tool_service.dart';
+export 'implementations/throttling_lang_tool_service.dart';
+export "presentation/language_tool_text_field.dart";
diff --git a/lib/presentation/language_tool_text_field.dart b/lib/presentation/language_tool_text_field.dart
index 0652baf..23e75df 100644
--- a/lib/presentation/language_tool_text_field.dart
+++ b/lib/presentation/language_tool_text_field.dart
@@ -1,4 +1,6 @@
+
 import 'package:flutter/material.dart';
+import 'package:languagetool_textfield/core/controllers/colored_text_editing_controller.dart';
 import 'package:languagetool_textfield/domain/language_check_service.dart';
 
 /// A TextField widget that checks the grammar using the given [langService]
@@ -29,8 +31,37 @@ class LanguageToolTextField extends StatefulWidget {
 }
 
 class _LanguageToolTextFieldState extends State<LanguageToolTextField> {
+  final ColoredTextEditingController _controller =
+      ColoredTextEditingController();
+  final int _maxLines = 8; // max lines of the TextFiled
+
+  /// Sends API request to get a list of Mistake
+  Future<void> _check(String text) async {
+    final list = await widget.langService.findMistakes(text);
+    if (list.isNotEmpty) {
+      _controller.setMistakes(list);
+    }
+  }
+
+  @override
+  void dispose() {
+    super.dispose();
+    _controller.dispose(); // disposes controller
+  }
+
   @override
   Widget build(BuildContext context) {
-    return const Placeholder();
+    return Padding(
+      padding: const EdgeInsets.all(24.0),
+      child: Center(
+        child: TextField(
+          controller: _controller,
+          maxLines: _maxLines,
+          onChanged: _check,
+          style: widget.style,
+          decoration: widget.decoration,
+        ),
+      ),
+    );
   }
 }