diff --git a/lib/src/butter.dart b/lib/src/butter.dart
index 5ed821b..3247143 100644
--- a/lib/src/butter.dart
+++ b/lib/src/butter.dart
@@ -9,12 +9,12 @@ class Butter {
   /// The API token for Butter user
   final String _apiKey;
 
-  Pages page;
-  Content content;
-  Posts post;
-  Authors author;
-  Categories category;
-  Tags tag;
+  Pages? page;
+  Content? content;
+  Posts? post;
+  Authors? author;
+  Categories? category;
+  Tags? tag;
 
   Butter(this._apiKey) {
     if (_apiKey == "") {
diff --git a/lib/src/files/authors.dart b/lib/src/files/authors.dart
index 95bfb1b..e7e3a6e 100644
--- a/lib/src/files/authors.dart
+++ b/lib/src/files/authors.dart
@@ -10,7 +10,7 @@ class Authors {
   /// Retrieves a single author using slug
   /// [params] is a Map used to add additional parameters to the query
   Future<Response> retrieve([
-    Map<String, String> params,
+    Map<String, String>? params,
   ]) {
     if (params != null)
       params["auth_token"] = _apiKey;
@@ -22,7 +22,7 @@ class Authors {
   /// Lists all authors
   /// [params] is a Map used to add additional parameters to the query
   Future<Response> list([
-    Map<String, String> params,
+    Map<String, String>? params,
   ]) {
     if (params != null)
       params["auth_token"] = _apiKey;
diff --git a/lib/src/files/categories.dart b/lib/src/files/categories.dart
index 33ea390..41cd23b 100644
--- a/lib/src/files/categories.dart
+++ b/lib/src/files/categories.dart
@@ -10,7 +10,7 @@ class Categories {
   /// Retrieves a single category using slug
   /// [params] is a Map used to add additional parameters to the query
   Future<Response> retrieve([
-    Map<String, String> params,
+    Map<String, String>? params,
   ]) {
     if (params != null)
       params["auth_token"] = _apiKey;
@@ -22,7 +22,7 @@ class Categories {
   /// Lists all categories
   /// [params] is a Map used to add additional parameters to the query
   Future<Response> list([
-    Map<String, String> params,
+    Map<String, String>? params,
   ]) {
     if (params != null)
       params["auth_token"] = _apiKey;
diff --git a/lib/src/files/content.dart b/lib/src/files/content.dart
index 0e659a7..ff01113 100644
--- a/lib/src/files/content.dart
+++ b/lib/src/files/content.dart
@@ -12,7 +12,7 @@ class Content {
   /// [params] is a Map used to add additional parameters to the query
   Future<Response> retrieve(
     List<String> keys, [
-    Map<String, String> params,
+    Map<String, String>? params,
   ]) {
     if (params != null)
       params["auth_token"] = _apiKey;
diff --git a/lib/src/files/pages.dart b/lib/src/files/pages.dart
index 3b818e0..ff48300 100644
--- a/lib/src/files/pages.dart
+++ b/lib/src/files/pages.dart
@@ -14,7 +14,7 @@ class Pages {
   Future<Response> retrieve(
     String pageType,
     String pageSlug, [
-    Map<String, String> params,
+    Map<String, String>? params,
   ]) {
     if (params != null)
       params["auth_token"] = _apiKey;
@@ -30,7 +30,7 @@ class Pages {
   /// [params] is a Map used to add additional parameters to the query
   Future<Response> list(
     String pageType, [
-    Map<String, String> params,
+    Map<String, String>? params,
   ]) {
     if (params != null)
       params["auth_token"] = _apiKey;
diff --git a/lib/src/files/posts.dart b/lib/src/files/posts.dart
index e26b836..3d24d11 100644
--- a/lib/src/files/posts.dart
+++ b/lib/src/files/posts.dart
@@ -11,7 +11,7 @@ class Posts {
   /// [params] is a Map used to add additional parameters to the query
   Future<Response> retrieve(
     String slug, [
-    Map<String, String> params,
+    Map<String, String>? params,
   ]) {
     if (params != null) {
       params["auth_token"] = _apiKey;
@@ -25,7 +25,7 @@ class Posts {
   /// Lists multiple posts according to page size
   /// [params] is a Map used to add additional parameters to the query
   Future<Response> list([
-    Map<String, String> params,
+    Map<String, String>? params,
   ]) {
     if (params != null)
       params["auth_token"] = _apiKey;
@@ -39,7 +39,7 @@ class Posts {
   /// [params] is a Map used to add additional parameters to the query
   Future<Response> search(
     String query, [
-    Map<String, String> params,
+    Map<String, String>? params,
   ]) {
     if (params != null) {
       params["auth_token"] = _apiKey;
diff --git a/lib/src/files/tags.dart b/lib/src/files/tags.dart
index 873f955..31b58b2 100644
--- a/lib/src/files/tags.dart
+++ b/lib/src/files/tags.dart
@@ -10,7 +10,7 @@ class Tags {
   /// Retrieves a single page from Pages
   /// [params] is a Map used to add additional parameters to the query
   Future<Response> retrieve([
-    Map<String, String> params,
+    Map<String, String>? params,
   ]) {
     if (params != null)
       params["auth_token"] = _apiKey;
@@ -22,7 +22,7 @@ class Tags {
   /// Retrieves multiple pages from a pageType of Pages
   /// [params] is a Map used to add additional parameters to the query
   Future<Response> list([
-    Map<String, String> params,
+    Map<String, String>? params,
   ]) {
     if (params != null)
       params["auth_token"] = _apiKey;
diff --git a/pubspec.lock b/pubspec.lock
index 5091f9b..066d95f 100644
--- a/pubspec.lock
+++ b/pubspec.lock
@@ -7,342 +7,342 @@ packages:
       name: _fe_analyzer_shared
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "11.0.0"
+    version: "21.0.0"
   analyzer:
     dependency: transitive
     description:
       name: analyzer
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.40.4"
+    version: "1.5.0"
   args:
     dependency: transitive
     description:
       name: args
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.6.0"
+    version: "2.1.0"
   async:
     dependency: transitive
     description:
       name: async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.5.0-nullsafety.1"
+    version: "2.6.1"
   boolean_selector:
     dependency: transitive
     description:
       name: boolean_selector
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.0-nullsafety.1"
+    version: "2.1.0"
   charcode:
     dependency: transitive
     description:
       name: charcode
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.2.0-nullsafety.1"
+    version: "1.2.0"
   cli_util:
     dependency: transitive
     description:
       name: cli_util
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.0"
+    version: "0.3.0"
   collection:
     dependency: transitive
     description:
       name: collection
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.15.0-nullsafety.3"
+    version: "1.15.0"
   convert:
     dependency: transitive
     description:
       name: convert
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.1"
+    version: "3.0.0"
   coverage:
     dependency: transitive
     description:
       name: coverage
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.14.1"
+    version: "1.0.2"
   crypto:
     dependency: transitive
     description:
       name: crypto
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.5"
+    version: "3.0.1"
+  file:
+    dependency: transitive
+    description:
+      name: file
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "6.1.0"
+  frontend_server_client:
+    dependency: transitive
+    description:
+      name: frontend_server_client
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.1.0"
   glob:
     dependency: transitive
     description:
       name: glob
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.2.0"
+    version: "2.0.1"
   http:
     dependency: "direct main"
     description:
       name: http
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.12.2"
+    version: "0.13.3"
   http_multi_server:
     dependency: transitive
     description:
       name: http_multi_server
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.2.0"
+    version: "3.0.1"
   http_parser:
     dependency: transitive
     description:
       name: http_parser
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "3.1.3"
+    version: "4.0.0"
   io:
     dependency: transitive
     description:
       name: io
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.3.4"
+    version: "1.0.0"
   js:
     dependency: transitive
     description:
       name: js
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.6.2"
+    version: "0.6.3"
   logging:
     dependency: transitive
     description:
       name: logging
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.11.4"
+    version: "1.0.1"
   matcher:
     dependency: transitive
     description:
       name: matcher
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.12.9"
+    version: "0.12.10"
   meta:
     dependency: transitive
     description:
       name: meta
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.3.0-nullsafety.3"
+    version: "1.3.0"
   mime:
     dependency: transitive
     description:
       name: mime
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.9.7"
-  node_interop:
-    dependency: transitive
-    description:
-      name: node_interop
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "1.1.1"
-  node_io:
-    dependency: transitive
-    description:
-      name: node_io
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "1.1.1"
+    version: "1.0.0"
   node_preamble:
     dependency: transitive
     description:
       name: node_preamble
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.4.12"
+    version: "2.0.0"
   package_config:
     dependency: transitive
     description:
       name: package_config
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.9.3"
+    version: "2.0.0"
   path:
     dependency: transitive
     description:
       name: path
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.8.0-nullsafety.1"
+    version: "1.8.0"
   pedantic:
     dependency: transitive
     description:
       name: pedantic
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.7.0"
+    version: "1.11.0"
   pool:
     dependency: transitive
     description:
       name: pool
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.4.0"
+    version: "1.5.0"
   pub_semver:
     dependency: transitive
     description:
       name: pub_semver
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.4.4"
+    version: "2.0.0"
   shelf:
     dependency: transitive
     description:
       name: shelf
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.7.9"
+    version: "1.1.2"
   shelf_packages_handler:
     dependency: transitive
     description:
       name: shelf_packages_handler
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.0.0"
+    version: "3.0.0"
   shelf_static:
     dependency: transitive
     description:
       name: shelf_static
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.8"
+    version: "1.0.0"
   shelf_web_socket:
     dependency: transitive
     description:
       name: shelf_web_socket
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.3"
+    version: "1.0.1"
   source_map_stack_trace:
     dependency: transitive
     description:
       name: source_map_stack_trace
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.0.0"
+    version: "2.1.0"
   source_maps:
     dependency: transitive
     description:
       name: source_maps
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.10.9"
+    version: "0.10.10"
   source_span:
     dependency: transitive
     description:
       name: source_span
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.8.0-nullsafety.2"
+    version: "1.8.1"
   stack_trace:
     dependency: transitive
     description:
       name: stack_trace
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.10.0-nullsafety.1"
+    version: "1.10.0"
   stream_channel:
     dependency: transitive
     description:
       name: stream_channel
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.1.0-nullsafety.1"
+    version: "2.1.0"
   string_scanner:
     dependency: transitive
     description:
       name: string_scanner
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.0-nullsafety.1"
+    version: "1.1.0"
   term_glyph:
     dependency: transitive
     description:
       name: term_glyph
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.2.0-nullsafety.1"
+    version: "1.2.0"
   test:
     dependency: "direct dev"
     description:
       name: test
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.15.4"
+    version: "1.17.3"
   test_api:
     dependency: transitive
     description:
       name: test_api
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.18"
+    version: "0.4.0"
   test_core:
     dependency: transitive
     description:
       name: test_core
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.3.11+1"
+    version: "0.3.23"
   typed_data:
     dependency: transitive
     description:
       name: typed_data
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.3.0-nullsafety.3"
+    version: "1.3.0"
   vm_service:
     dependency: transitive
     description:
       name: vm_service
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "4.2.0"
+    version: "6.2.0"
   watcher:
     dependency: transitive
     description:
       name: watcher
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.9.7+15"
+    version: "1.0.0"
   web_socket_channel:
     dependency: transitive
     description:
       name: web_socket_channel
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.1.0"
+    version: "2.1.0"
   webkit_inspection_protocol:
     dependency: transitive
     description:
       name: webkit_inspection_protocol
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.7.3"
+    version: "1.0.0"
   yaml:
     dependency: transitive
     description:
       name: yaml
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.2.1"
+    version: "3.1.0"
 sdks:
-  dart: ">=2.10.0-78 <=2.11.0-161.0.dev"
+  dart: ">=2.12.0 <3.0.0"
diff --git a/pubspec.yaml b/pubspec.yaml
index 5a800ad..1e04775 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,19 +1,19 @@
 name: buttercms_dart
 description: The official ButterCMS package for Flutter. Use the full feature set Butter offers, now available on Flutter.
-version: 0.2.0
+version: 0.3.0
 authors:
   - ButterCMS Team <support@buttercms.com>
   - Deven Joshi <deven9852@gmail.com>
 homepage: https://github.com/ButterCMS/buttercms-dart
 
 environment:
-  sdk: ">=2.1.0 <3.0.0"
+  sdk: '>=2.12.0 <3.0.0'
 
 dependencies:
-  http: ^0.12.2
+  http: ^0.13.3
 
 dev_dependencies:
-  test: 1.15.4
+  test: 1.17.3
 
 # For information on the generic Dart part of this file, see the
 # following page: https://dart.dev/tools/pub/pubspec