diff --git a/lib/providers/collection_providers.dart b/lib/providers/collection_providers.dart
index b5ff9da6..5230e39f 100644
--- a/lib/providers/collection_providers.dart
+++ b/lib/providers/collection_providers.dart
@@ -4,7 +4,8 @@ import 'package:apidash/consts.dart';
 import 'providers.dart';
 import '../models/models.dart';
 import '../services/services.dart' show hiveHandler, HiveHandler, request;
-import '../utils/utils.dart' show getNewUuid, collectionToHAR;
+import '../utils/utils.dart'
+    show getNewUuid, collectionToHAR, substituteHttpRequestModel;
 
 final selectedIdStateProvider = StateProvider<String?>((ref) => null);
 
@@ -205,6 +206,9 @@ class CollectionStateNotifier
       return;
     }
 
+    HttpRequestModel substitutedHttpRequestModel =
+        getSubstitutedHttpRequestModel(requestModel.httpRequestModel!);
+
     // set current model's isWorking to true and update state
     var map = {...state!};
     map[id] = requestModel.copyWith(
@@ -214,7 +218,7 @@ class CollectionStateNotifier
     state = map;
 
     (http.Response?, Duration?, String?)? responseRec = await request(
-      requestModel.httpRequestModel!,
+      substitutedHttpRequestModel,
       defaultUriScheme: defaultUriScheme,
     );
     late final RequestModel newRequestModel;
@@ -311,4 +315,16 @@ class CollectionStateNotifier
     //   "data": state!.map((e) => e.toJson(includeResponse: false)).toList()
     // };
   }
+
+  HttpRequestModel getSubstitutedHttpRequestModel(
+      HttpRequestModel httpRequestModel) {
+    var envMap = ref.read(availableEnvironmentVariablesStateProvider);
+    var activeEnvId = ref.read(activeEnvironmentIdStateProvider);
+
+    return substituteHttpRequestModel(
+      httpRequestModel,
+      envMap,
+      activeEnvId,
+    );
+  }
 }
diff --git a/lib/providers/settings_providers.dart b/lib/providers/settings_providers.dart
index fe49ff8a..69ec4f1a 100644
--- a/lib/providers/settings_providers.dart
+++ b/lib/providers/settings_providers.dart
@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import '../models/models.dart' show SettingsModel;
+import '../models/models.dart';
+import 'environment_provider.dart';
 import '../services/services.dart' show hiveHandler, HiveHandler;
 import '../consts.dart';
 
@@ -10,6 +11,26 @@ final codegenLanguageStateProvider = StateProvider<CodegenLanguage>((ref) =>
 final activeEnvironmentIdStateProvider = StateProvider<String?>((ref) =>
     ref.watch(settingsProvider.select((value) => value.activeEnvironmentId)));
 
+final availableEnvironmentVariablesStateProvider =
+    StateProvider<Map<String, List<EnvironmentVariableModel>>>((ref) {
+  Map<String, List<EnvironmentVariableModel>> result = {};
+  final environments = ref.watch(environmentsStateNotifierProvider);
+  final activeEnviormentId = ref.watch(activeEnvironmentIdStateProvider);
+  if (activeEnviormentId != null) {
+    result[activeEnviormentId] = environments?[activeEnviormentId]
+            ?.values
+            .where((element) => element.enabled)
+            .toList() ??
+        [];
+  }
+  result[kGlobalEnvironmentId] = environments?[kGlobalEnvironmentId]
+          ?.values
+          .where((element) => element.enabled)
+          .toList() ??
+      [];
+  return result;
+});
+
 final StateNotifierProvider<ThemeStateNotifier, SettingsModel>
     settingsProvider =
     StateNotifierProvider((ref) => ThemeStateNotifier(hiveHandler));
diff --git a/lib/screens/common/main_editor_widgets.dart b/lib/screens/common/main_editor_widgets.dart
index 21f71b89..5453d226 100644
--- a/lib/screens/common/main_editor_widgets.dart
+++ b/lib/screens/common/main_editor_widgets.dart
@@ -85,6 +85,7 @@ class EnvironmentDropdown extends ConsumerWidget {
         environments: environmentsList,
         onChanged: (value) {
           ref.read(activeEnvironmentIdStateProvider.notifier).state = value?.id;
+          ref.read(hasUnsavedChangesProvider.notifier).state = true;
         },
       ),
     );
diff --git a/lib/screens/envvar/editor_pane/secrets_pane.dart b/lib/screens/envvar/editor_pane/secrets_pane.dart
index fb990d45..dcbec52e 100644
--- a/lib/screens/envvar/editor_pane/secrets_pane.dart
+++ b/lib/screens/envvar/editor_pane/secrets_pane.dart
@@ -89,8 +89,10 @@ class EditEnvironmentSecretsState
                     ? null
                     : (value) {
                         if (value != null) {
-                          secretRows[index] =
-                              secretRows[index].copyWith(enabled: value);
+                          setState(() {
+                            secretRows[index] =
+                                secretRows[index].copyWith(enabled: value);
+                          });
                         }
                         _onFieldChange(selectedId!);
                       },
diff --git a/lib/screens/envvar/editor_pane/variables_pane.dart b/lib/screens/envvar/editor_pane/variables_pane.dart
index 078be4b2..639fe9f5 100644
--- a/lib/screens/envvar/editor_pane/variables_pane.dart
+++ b/lib/screens/envvar/editor_pane/variables_pane.dart
@@ -89,8 +89,10 @@ class EditEnvironmentVariablesState
                     ? null
                     : (value) {
                         if (value != null) {
-                          variableRows[index] =
-                              variableRows[index].copyWith(enabled: value);
+                          setState(() {
+                            variableRows[index] =
+                                variableRows[index].copyWith(enabled: value);
+                          });
                         }
                         _onFieldChange(selectedId!);
                       },
diff --git a/lib/screens/home_page/editor_pane/details_card/code_pane.dart b/lib/screens/home_page/editor_pane/details_card/code_pane.dart
index 7cc39ef6..f61c10a6 100644
--- a/lib/screens/home_page/editor_pane/details_card/code_pane.dart
+++ b/lib/screens/home_page/editor_pane/details_card/code_pane.dart
@@ -3,6 +3,7 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:apidash/providers/providers.dart';
 import 'package:apidash/widgets/widgets.dart';
 import 'package:apidash/codegen/codegen.dart';
+import 'package:apidash/utils/utils.dart';
 import 'package:apidash/consts.dart';
 
 final Codegen codegen = Codegen();
@@ -19,8 +20,15 @@ class CodePane extends ConsumerWidget {
     final defaultUriScheme =
         ref.watch(settingsProvider.select((value) => value.defaultUriScheme));
 
+    var envMap = ref.watch(availableEnvironmentVariablesStateProvider);
+    var activeEnvId = ref.watch(activeEnvironmentIdStateProvider);
+
+    final substitutedRequestModel = selectedRequestModel?.copyWith(
+        httpRequestModel: substituteHttpRequestModel(
+            selectedRequestModel.httpRequestModel!, envMap, activeEnvId));
+
     final code = codegen.getCode(
-        codegenLanguage, selectedRequestModel!, defaultUriScheme);
+        codegenLanguage, substitutedRequestModel!, defaultUriScheme);
     if (code == null) {
       return const ErrorMessage(
         message: "An error was encountered while generating code. $kRaiseIssue",
diff --git a/lib/utils/envvar_utils.dart b/lib/utils/envvar_utils.dart
index 80d1bb35..7057d7f2 100644
--- a/lib/utils/envvar_utils.dart
+++ b/lib/utils/envvar_utils.dart
@@ -35,3 +35,53 @@ List<EnvironmentVariableModel> getEnvironmentSecrets(
           (removeEmptyModels ? element != kEnvironmentSecretEmptyModel : true))
       .toList();
 }
+
+String? substituteVariables(
+    String? input,
+    Map<String?, List<EnvironmentVariableModel>> envMap,
+    String? activeEnvironmentId) {
+  if (input == null) return null;
+
+  final Map<String, String> combinedMap = {};
+  final activeEnv = envMap[activeEnvironmentId] ?? [];
+  final globalEnv = envMap[kGlobalEnvironmentId] ?? [];
+
+  for (var variable in globalEnv) {
+    combinedMap[variable.key] = variable.value;
+  }
+  for (var variable in activeEnv) {
+    combinedMap[variable.key] = variable.value;
+  }
+
+  final regex = RegExp(r'{{(.*?)}}');
+  String result = input.replaceAllMapped(regex, (match) {
+    final key = match.group(1)?.trim() ?? '';
+    return combinedMap[key] ?? '';
+  });
+
+  return result;
+}
+
+HttpRequestModel substituteHttpRequestModel(
+    HttpRequestModel httpRequestModel,
+    Map<String?, List<EnvironmentVariableModel>> envMap,
+    String? activeEnvironmentId) {
+  var newRequestModel = httpRequestModel.copyWith(
+    url: substituteVariables(
+      httpRequestModel.url,
+      envMap,
+      activeEnvironmentId,
+    )!,
+    headers: httpRequestModel.headers?.map((header) {
+      return header.copyWith(
+        value: substituteVariables(header.value, envMap, activeEnvironmentId),
+      );
+    }).toList(),
+    params: httpRequestModel.params?.map((param) {
+      return param.copyWith(
+        value: substituteVariables(param.value, envMap, activeEnvironmentId),
+      );
+    }).toList(),
+  );
+  return newRequestModel;
+}