diff --git a/.travis.yml b/.travis.yml
index 6503749a81..18de1e947d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,23 +1,35 @@
 language: dart
 
 dart:
-  - dev
-  - 2.4.0
+- dev
 
-dart_task:
-  - test: --platform vm,chrome
-  - dartanalyzer: --fatal-infos --fatal-warnings .
-
-matrix:
+jobs:
   include:
-  # Only validate formatting using the dev release
-  - dart: dev
-    dart_task: dartfmt
+  - stage: analyze_and_format
+    name: "Analyze"
+    os: linux
+    script: dartanalyzer --enable-experiment=non-nullable --fatal-warnings --fatal-infos .
+  - stage: analyze_and_format
+    name: "Format"
+    os: linux
+    script: dartfmt -n --set-exit-if-changed .
+  - stage: test
+    name: "Vm Tests"
+    os: linux
+    script: pub run --enable-experiment=non-nullable test -p vm
+  - stage: test
+    name: "Web Tests"
+    os: linux
+    script: pub run --enable-experiment=non-nullable test -p chrome
+
+stages:
+- analyze_and_format
+- test
 
 # Only building master means that we don't run two builds for each pull request.
 branches:
   only: [master]
 
 cache:
- directories:
-   - $HOME/.pub-cache
+  directories:
+  - $HOME/.pub-cache
diff --git a/CHANGELOG.md b/CHANGELOG.md
index f9cc8654fe..9d294c1f10 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,16 @@
+## 0.13.0-nullsafety-dev
+
+Pre-release for the null safety migration of this package.
+
+Note that 0.12.3 may not be the final stable null safety release version, we
+reserve the right to release it as a 0.13.0 breaking change.
+
+This release will be pinned to only allow pre-release sdk versions starting from
+2.10.0-2.0.dev, which is the first version where this package will appear in the
+null safety allow list.
+
+- Added `const` constructor to `ByteStream`.
+
 ## 0.12.2
 
 * Fix error handler callback type for response stream errors to avoid masking
diff --git a/analysis_options.yaml b/analysis_options.yaml
index 60a8ea8a36..e4a95424f2 100644
--- a/analysis_options.yaml
+++ b/analysis_options.yaml
@@ -1,7 +1,11 @@
 include: package:pedantic/analysis_options.yaml
+
 analyzer:
   strong-mode:
     implicit-casts: false
+  enable-experiment:
+  - non-nullable
+
 linter:
   rules:
   - annotate_overrides
diff --git a/lib/http.dart b/lib/http.dart
index 5539cfa8eb..4f918831a8 100644
--- a/lib/http.dart
+++ b/lib/http.dart
@@ -30,7 +30,7 @@ export 'src/streamed_response.dart';
 /// the same server, you should use a single [Client] for all of those requests.
 ///
 /// For more fine-grained control over the request, use [Request] instead.
-Future<Response> head(url, {Map<String, String> headers}) =>
+Future<Response> head(Object url, {Map<String, String>? headers}) =>
     _withClient((client) => client.head(url, headers: headers));
 
 /// Sends an HTTP GET request with the given headers to the given URL, which can
@@ -41,7 +41,7 @@ Future<Response> head(url, {Map<String, String> headers}) =>
 /// the same server, you should use a single [Client] for all of those requests.
 ///
 /// For more fine-grained control over the request, use [Request] instead.
-Future<Response> get(url, {Map<String, String> headers}) =>
+Future<Response> get(Object url, {Map<String, String>? headers}) =>
     _withClient((client) => client.get(url, headers: headers));
 
 /// Sends an HTTP POST request with the given headers and body to the given URL,
@@ -63,8 +63,8 @@ Future<Response> get(url, {Map<String, String> headers}) =>
 ///
 /// For more fine-grained control over the request, use [Request] or
 /// [StreamedRequest] instead.
-Future<Response> post(url,
-        {Map<String, String> headers, body, Encoding encoding}) =>
+Future<Response> post(Object url,
+        {Map<String, String>? headers, Object? body, Encoding? encoding}) =>
     _withClient((client) =>
         client.post(url, headers: headers, body: body, encoding: encoding));
 
@@ -87,8 +87,8 @@ Future<Response> post(url,
 ///
 /// For more fine-grained control over the request, use [Request] or
 /// [StreamedRequest] instead.
-Future<Response> put(url,
-        {Map<String, String> headers, body, Encoding encoding}) =>
+Future<Response> put(Object url,
+        {Map<String, String>? headers, Object? body, Encoding? encoding}) =>
     _withClient((client) =>
         client.put(url, headers: headers, body: body, encoding: encoding));
 
@@ -111,8 +111,8 @@ Future<Response> put(url,
 ///
 /// For more fine-grained control over the request, use [Request] or
 /// [StreamedRequest] instead.
-Future<Response> patch(url,
-        {Map<String, String> headers, body, Encoding encoding}) =>
+Future<Response> patch(Object url,
+        {Map<String, String>? headers, Object? body, Encoding? encoding}) =>
     _withClient((client) =>
         client.patch(url, headers: headers, body: body, encoding: encoding));
 
@@ -124,7 +124,7 @@ Future<Response> patch(url,
 /// the same server, you should use a single [Client] for all of those requests.
 ///
 /// For more fine-grained control over the request, use [Request] instead.
-Future<Response> delete(url, {Map<String, String> headers}) =>
+Future<Response> delete(Object url, {Map<String, String>? headers}) =>
     _withClient((client) => client.delete(url, headers: headers));
 
 /// Sends an HTTP GET request with the given headers to the given URL, which can
@@ -140,7 +140,7 @@ Future<Response> delete(url, {Map<String, String> headers}) =>
 ///
 /// For more fine-grained control over the request and response, use [Request]
 /// instead.
-Future<String> read(url, {Map<String, String> headers}) =>
+Future<String> read(Object url, {Map<String, String>? headers}) =>
     _withClient((client) => client.read(url, headers: headers));
 
 /// Sends an HTTP GET request with the given headers to the given URL, which can
@@ -156,7 +156,7 @@ Future<String> read(url, {Map<String, String> headers}) =>
 ///
 /// For more fine-grained control over the request and response, use [Request]
 /// instead.
-Future<Uint8List> readBytes(url, {Map<String, String> headers}) =>
+Future<Uint8List> readBytes(Object url, {Map<String, String>? headers}) =>
     _withClient((client) => client.readBytes(url, headers: headers));
 
 Future<T> _withClient<T>(Future<T> Function(Client) fn) async {
diff --git a/lib/src/base_client.dart b/lib/src/base_client.dart
index 640afb869a..c47bb1071a 100644
--- a/lib/src/base_client.dart
+++ b/lib/src/base_client.dart
@@ -18,40 +18,42 @@ import 'streamed_response.dart';
 /// maybe [close], and then they get various convenience methods for free.
 abstract class BaseClient implements Client {
   @override
-  Future<Response> head(url, {Map<String, String> headers}) =>
+  Future<Response> head(Object url, {Map<String, String>? headers}) =>
       _sendUnstreamed('HEAD', url, headers);
 
   @override
-  Future<Response> get(url, {Map<String, String> headers}) =>
+  Future<Response> get(Object url, {Map<String, String>? headers}) =>
       _sendUnstreamed('GET', url, headers);
 
   @override
-  Future<Response> post(url,
-          {Map<String, String> headers, body, Encoding encoding}) =>
+  Future<Response> post(Object url,
+          {Map<String, String>? headers, Object? body, Encoding? encoding}) =>
       _sendUnstreamed('POST', url, headers, body, encoding);
 
   @override
-  Future<Response> put(url,
-          {Map<String, String> headers, body, Encoding encoding}) =>
+  Future<Response> put(Object url,
+          {Map<String, String>? headers, Object? body, Encoding? encoding}) =>
       _sendUnstreamed('PUT', url, headers, body, encoding);
 
   @override
-  Future<Response> patch(url,
-          {Map<String, String> headers, body, Encoding encoding}) =>
+  Future<Response> patch(Object url,
+          {Map<String, String>? headers, Object? body, Encoding? encoding}) =>
       _sendUnstreamed('PATCH', url, headers, body, encoding);
 
   @override
-  Future<Response> delete(url, {Map<String, String> headers}) =>
+  Future<Response> delete(Object url, {Map<String, String>? headers}) =>
       _sendUnstreamed('DELETE', url, headers);
+
   @override
-  Future<String> read(url, {Map<String, String> headers}) async {
+  Future<String> read(Object url, {Map<String, String>? headers}) async {
     final response = await get(url, headers: headers);
     _checkResponseSuccess(url, response);
     return response.body;
   }
 
   @override
-  Future<Uint8List> readBytes(url, {Map<String, String> headers}) async {
+  Future<Uint8List> readBytes(Object url,
+      {Map<String, String>? headers}) async {
     final response = await get(url, headers: headers);
     _checkResponseSuccess(url, response);
     return response.bodyBytes;
@@ -69,8 +71,8 @@ abstract class BaseClient implements Client {
 
   /// Sends a non-streaming [Request] and returns a non-streaming [Response].
   Future<Response> _sendUnstreamed(
-      String method, url, Map<String, String> headers,
-      [body, Encoding encoding]) async {
+      String method, url, Map<String, String>? headers,
+      [body, Encoding? encoding]) async {
     var request = Request(method, _fromUriOrString(url));
 
     if (headers != null) request.headers.addAll(headers);
diff --git a/lib/src/base_request.dart b/lib/src/base_request.dart
index 93c545f634..9d1db4b5b1 100644
--- a/lib/src/base_request.dart
+++ b/lib/src/base_request.dart
@@ -4,6 +4,8 @@
 
 import 'dart:collection';
 
+import 'package:meta/meta.dart';
+
 import 'byte_stream.dart';
 import 'client.dart';
 import 'streamed_response.dart';
@@ -29,10 +31,10 @@ abstract class BaseRequest {
   ///
   /// This defaults to `null`, which indicates that the size of the request is
   /// not known in advance. May not be assigned a negative value.
-  int get contentLength => _contentLength;
-  int _contentLength;
+  int? get contentLength => _contentLength;
+  int? _contentLength;
 
-  set contentLength(int value) {
+  set contentLength(int? value) {
     if (value != null && value < 0) {
       throw ArgumentError('Invalid content length $value.');
     }
@@ -93,16 +95,17 @@ abstract class BaseRequest {
   /// Freezes all mutable fields and returns a single-subscription [ByteStream]
   /// that emits the body of the request.
   ///
-  /// The base implementation of this returns null rather than a [ByteStream];
+  /// The base implementation of this returns an empty [ByteStream];
   /// subclasses are responsible for creating the return value, which should be
   /// single-subscription to ensure that no data is dropped. They should also
   /// freeze any additional mutable fields they add that don't make sense to
   /// change after the request headers are sent.
+  @mustCallSuper
   ByteStream finalize() {
     // TODO(nweiz): freeze headers
     if (finalized) throw StateError("Can't finalize a finalized Request.");
     _finalized = true;
-    return null;
+    return const ByteStream(Stream.empty());
   }
 
   /// Sends this request.
diff --git a/lib/src/base_response.dart b/lib/src/base_response.dart
index 6e2fc13bff..5040245fae 100644
--- a/lib/src/base_response.dart
+++ b/lib/src/base_response.dart
@@ -10,18 +10,18 @@ import 'base_request.dart';
 /// they're returned by [BaseClient.send] or other HTTP client methods.
 abstract class BaseResponse {
   /// The (frozen) request that triggered this response.
-  final BaseRequest request;
+  final BaseRequest? request;
 
   /// The HTTP status code for this response.
   final int statusCode;
 
   /// The reason phrase associated with the status code.
-  final String reasonPhrase;
+  final String? reasonPhrase;
 
   /// The size of the response body, in bytes.
   ///
   /// If the size of the request is not known in advance, this is `null`.
-  final int contentLength;
+  final int? contentLength;
 
   // TODO(nweiz): automatically parse cookies from headers
 
@@ -42,7 +42,7 @@ abstract class BaseResponse {
       this.reasonPhrase}) {
     if (statusCode < 100) {
       throw ArgumentError('Invalid status code $statusCode.');
-    } else if (contentLength != null && contentLength < 0) {
+    } else if (contentLength != null && contentLength! < 0) {
       throw ArgumentError('Invalid content length $contentLength.');
     }
   }
diff --git a/lib/src/browser_client.dart b/lib/src/browser_client.dart
index 1fb25b5a3f..3980bc0e26 100644
--- a/lib/src/browser_client.dart
+++ b/lib/src/browser_client.dart
@@ -52,16 +52,17 @@ class BrowserClient extends BaseClient {
     request.headers.forEach(xhr.setRequestHeader);
 
     var completer = Completer<StreamedResponse>();
+
+    // TODO(kevmoo): Waiting on  https://github.com/dart-lang/linter/issues/2185
+    // ignore: void_checks
     unawaited(xhr.onLoad.first.then((_) {
-      // TODO(nweiz): Set the response type to "arraybuffer" when issue 18542
-      // is fixed.
-      var blob = xhr.response as Blob ?? Blob([]);
+      var blob = xhr.response as Blob;
       var reader = FileReader();
 
       reader.onLoad.first.then((_) {
         var body = reader.result as Uint8List;
         completer.complete(StreamedResponse(
-            ByteStream.fromBytes(body), xhr.status,
+            ByteStream.fromBytes(body), xhr.status!,
             contentLength: body.length,
             request: request,
             headers: xhr.responseHeaders,
@@ -76,6 +77,8 @@ class BrowserClient extends BaseClient {
       reader.readAsArrayBuffer(blob);
     }));
 
+    // TODO(kevmoo): Waiting on  https://github.com/dart-lang/linter/issues/2185
+    // ignore: void_checks
     unawaited(xhr.onError.first.then((_) {
       // Unfortunately, the underlying XMLHttpRequest API doesn't expose any
       // specific information about the error itself.
diff --git a/lib/src/byte_stream.dart b/lib/src/byte_stream.dart
index 0191a05cb9..172db0d6c0 100644
--- a/lib/src/byte_stream.dart
+++ b/lib/src/byte_stream.dart
@@ -8,7 +8,7 @@ import 'dart:typed_data';
 
 /// A stream of chunks of bytes representing a single piece of data.
 class ByteStream extends StreamView<List<int>> {
-  ByteStream(Stream<List<int>> stream) : super(stream);
+  const ByteStream(Stream<List<int>> stream) : super(stream);
 
   /// Returns a single-subscription byte stream that will emit the given bytes
   /// in a single chunk.
diff --git a/lib/src/client.dart b/lib/src/client.dart
index 89b1b10c63..3a1c33efb0 100644
--- a/lib/src/client.dart
+++ b/lib/src/client.dart
@@ -7,11 +7,8 @@ import 'dart:typed_data';
 
 import 'base_client.dart';
 import 'base_request.dart';
-// ignore: uri_does_not_exist
 import 'client_stub.dart'
-    // ignore: uri_does_not_exist
     if (dart.library.html) 'browser_client.dart'
-    // ignore: uri_does_not_exist
     if (dart.library.io) 'io_client.dart';
 import 'response.dart';
 import 'streamed_response.dart';
@@ -37,13 +34,13 @@ abstract class Client {
   /// can be a [Uri] or a [String].
   ///
   /// For more fine-grained control over the request, use [send] instead.
-  Future<Response> head(url, {Map<String, String> headers});
+  Future<Response> head(Object url, {Map<String, String>? headers});
 
   /// Sends an HTTP GET request with the given headers to the given URL, which
   /// can be a [Uri] or a [String].
   ///
   /// For more fine-grained control over the request, use [send] instead.
-  Future<Response> get(url, {Map<String, String> headers});
+  Future<Response> get(Object url, {Map<String, String>? headers});
 
   /// Sends an HTTP POST request with the given headers and body to the given
   /// URL, which can be a [Uri] or a [String].
@@ -63,8 +60,8 @@ abstract class Client {
   /// [encoding] defaults to [utf8].
   ///
   /// For more fine-grained control over the request, use [send] instead.
-  Future<Response> post(url,
-      {Map<String, String> headers, body, Encoding encoding});
+  Future<Response> post(Object url,
+      {Map<String, String>? headers, Object? body, Encoding? encoding});
 
   /// Sends an HTTP PUT request with the given headers and body to the given
   /// URL, which can be a [Uri] or a [String].
@@ -84,8 +81,8 @@ abstract class Client {
   /// [encoding] defaults to [utf8].
   ///
   /// For more fine-grained control over the request, use [send] instead.
-  Future<Response> put(url,
-      {Map<String, String> headers, body, Encoding encoding});
+  Future<Response> put(Object url,
+      {Map<String, String>? headers, Object? body, Encoding? encoding});
 
   /// Sends an HTTP PATCH request with the given headers and body to the given
   /// URL, which can be a [Uri] or a [String].
@@ -105,14 +102,14 @@ abstract class Client {
   /// [encoding] defaults to [utf8].
   ///
   /// For more fine-grained control over the request, use [send] instead.
-  Future<Response> patch(url,
-      {Map<String, String> headers, body, Encoding encoding});
+  Future<Response> patch(Object url,
+      {Map<String, String>? headers, Object? body, Encoding? encoding});
 
   /// Sends an HTTP DELETE request with the given headers to the given URL,
   /// which can be a [Uri] or a [String].
   ///
   /// For more fine-grained control over the request, use [send] instead.
-  Future<Response> delete(url, {Map<String, String> headers});
+  Future<Response> delete(Object url, {Map<String, String>? headers});
 
   /// Sends an HTTP GET request with the given headers to the given URL, which
   /// can be a [Uri] or a [String], and returns a Future that completes to the
@@ -123,7 +120,7 @@ abstract class Client {
   ///
   /// For more fine-grained control over the request and response, use [send] or
   /// [get] instead.
-  Future<String> read(url, {Map<String, String> headers});
+  Future<String> read(Object url, {Map<String, String>? headers});
 
   /// Sends an HTTP GET request with the given headers to the given URL, which
   /// can be a [Uri] or a [String], and returns a Future that completes to the
@@ -134,7 +131,7 @@ abstract class Client {
   ///
   /// For more fine-grained control over the request and response, use [send] or
   /// [get] instead.
-  Future<Uint8List> readBytes(url, {Map<String, String> headers});
+  Future<Uint8List> readBytes(Object url, {Map<String, String>? headers});
 
   /// Sends an HTTP request and asynchronously returns the response.
   Future<StreamedResponse> send(BaseRequest request);
diff --git a/lib/src/exception.dart b/lib/src/exception.dart
index c92a861a5b..5ac1a6441d 100644
--- a/lib/src/exception.dart
+++ b/lib/src/exception.dart
@@ -7,7 +7,7 @@ class ClientException implements Exception {
   final String message;
 
   /// The URL of the HTTP request or response that failed.
-  final Uri uri;
+  final Uri? uri;
 
   ClientException(this.message, [this.uri]);
 
diff --git a/lib/src/io_client.dart b/lib/src/io_client.dart
index d4f166e786..10539ce0a3 100644
--- a/lib/src/io_client.dart
+++ b/lib/src/io_client.dart
@@ -18,9 +18,9 @@ BaseClient createClient() => IOClient();
 /// A `dart:io`-based HTTP client.
 class IOClient extends BaseClient {
   /// The underlying `dart:io` HTTP client.
-  HttpClient _inner;
+  HttpClient? _inner;
 
-  IOClient([HttpClient inner]) : _inner = inner ?? HttpClient();
+  IOClient([HttpClient? inner]) : _inner = inner ?? HttpClient();
 
   /// Sends an HTTP request and asynchronously returns the response.
   @override
@@ -28,10 +28,10 @@ class IOClient extends BaseClient {
     var stream = request.finalize();
 
     try {
-      var ioRequest = (await _inner.openUrl(request.method, request.url))
+      var ioRequest = (await _inner!.openUrl(request.method, request.url))
         ..followRedirects = request.followRedirects
         ..maxRedirects = request.maxRedirects
-        ..contentLength = (request?.contentLength ?? -1)
+        ..contentLength = (request.contentLength ?? -1)
         ..persistentConnection = request.persistentConnection;
       request.headers.forEach((name, value) {
         ioRequest.headers.set(name, value);
@@ -70,7 +70,7 @@ class IOClient extends BaseClient {
   @override
   void close() {
     if (_inner != null) {
-      _inner.close(force: true);
+      _inner!.close(force: true);
       _inner = null;
     }
   }
diff --git a/lib/src/io_streamed_response.dart b/lib/src/io_streamed_response.dart
index fc69837b69..21744858b3 100644
--- a/lib/src/io_streamed_response.dart
+++ b/lib/src/io_streamed_response.dart
@@ -10,19 +10,21 @@ import 'streamed_response.dart';
 /// An HTTP response where the response body is received asynchronously after
 /// the headers have been received.
 class IOStreamedResponse extends StreamedResponse {
-  final HttpClientResponse _inner;
+  final HttpClientResponse? _inner;
 
   /// Creates a new streaming response.
   ///
   /// [stream] should be a single-subscription stream.
+  ///
+  /// If [inner] is not provided, [detachSocket] will throw.
   IOStreamedResponse(Stream<List<int>> stream, int statusCode,
-      {int contentLength,
-      BaseRequest request,
+      {int? contentLength,
+      BaseRequest? request,
       Map<String, String> headers = const {},
       bool isRedirect = false,
       bool persistentConnection = true,
-      String reasonPhrase,
-      HttpClientResponse inner})
+      String? reasonPhrase,
+      HttpClientResponse? inner})
       : _inner = inner,
         super(stream, statusCode,
             contentLength: contentLength,
@@ -33,5 +35,7 @@ class IOStreamedResponse extends StreamedResponse {
             reasonPhrase: reasonPhrase);
 
   /// Detaches the underlying socket from the HTTP server.
-  Future<Socket> detachSocket() async => _inner.detachSocket();
+  ///
+  /// Will throw if `inner` was not set or `null` when `this` was created.
+  Future<Socket> detachSocket() async => _inner!.detachSocket();
 }
diff --git a/lib/src/multipart_file.dart b/lib/src/multipart_file.dart
index 8e6642f001..772493adb0 100644
--- a/lib/src/multipart_file.dart
+++ b/lib/src/multipart_file.dart
@@ -7,10 +7,7 @@ import 'dart:convert';
 import 'package:http_parser/http_parser.dart';
 
 import 'byte_stream.dart';
-// ignore: uri_does_not_exist
-import 'multipart_file_stub.dart'
-    // ignore: uri_does_not_exist
-    if (dart.library.io) 'multipart_file_io.dart';
+import 'multipart_file_stub.dart' if (dart.library.io) 'multipart_file_io.dart';
 import 'utils.dart';
 
 /// A file to be uploaded as part of a [MultipartRequest].
@@ -28,8 +25,8 @@ class MultipartFile {
 
   /// The basename of the file.
   ///
-  /// May be null.
-  final String filename;
+  /// May be `null`.
+  final String? filename;
 
   /// The content-type of the file.
   ///
@@ -51,7 +48,7 @@ class MultipartFile {
   /// [contentType] currently defaults to `application/octet-stream`, but in the
   /// future may be inferred from [filename].
   MultipartFile(this.field, Stream<List<int>> stream, this.length,
-      {this.filename, MediaType contentType})
+      {this.filename, MediaType? contentType})
       : _stream = toByteStream(stream),
         contentType = contentType ?? MediaType('application', 'octet-stream');
 
@@ -60,7 +57,7 @@ class MultipartFile {
   /// [contentType] currently defaults to `application/octet-stream`, but in the
   /// future may be inferred from [filename].
   factory MultipartFile.fromBytes(String field, List<int> value,
-      {String filename, MediaType contentType}) {
+      {String? filename, MediaType? contentType}) {
     var stream = ByteStream.fromBytes(value);
     return MultipartFile(field, stream, value.length,
         filename: filename, contentType: contentType);
@@ -73,7 +70,7 @@ class MultipartFile {
   /// [contentType] currently defaults to `text/plain; charset=utf-8`, but in
   /// the future may be inferred from [filename].
   factory MultipartFile.fromString(String field, String value,
-      {String filename, MediaType contentType}) {
+      {String? filename, MediaType? contentType}) {
     contentType ??= MediaType('text', 'plain');
     var encoding = encodingForCharset(contentType.parameters['charset'], utf8);
     contentType = contentType.change(parameters: {'charset': encoding.name});
@@ -92,7 +89,7 @@ class MultipartFile {
   /// Throws an [UnsupportedError] if `dart:io` isn't supported in this
   /// environment.
   static Future<MultipartFile> fromPath(String field, String filePath,
-          {String filename, MediaType contentType}) =>
+          {String? filename, MediaType? contentType}) =>
       multipartFileFromPath(field, filePath,
           filename: filename, contentType: contentType);
 
diff --git a/lib/src/multipart_file_io.dart b/lib/src/multipart_file_io.dart
index bffc394b6b..1eaa918a2a 100644
--- a/lib/src/multipart_file_io.dart
+++ b/lib/src/multipart_file_io.dart
@@ -11,7 +11,7 @@ import 'byte_stream.dart';
 import 'multipart_file.dart';
 
 Future<MultipartFile> multipartFileFromPath(String field, String filePath,
-    {String filename, MediaType contentType}) async {
+    {String? filename, MediaType? contentType}) async {
   filename ??= p.basename(filePath);
   var file = File(filePath);
   var length = await file.length();
diff --git a/lib/src/multipart_file_stub.dart b/lib/src/multipart_file_stub.dart
index 30ed036c52..326914b50d 100644
--- a/lib/src/multipart_file_stub.dart
+++ b/lib/src/multipart_file_stub.dart
@@ -7,6 +7,6 @@ import 'package:http_parser/http_parser.dart';
 import 'multipart_file.dart';
 
 Future<MultipartFile> multipartFileFromPath(String field, String filePath,
-        {String filename, MediaType contentType}) =>
+        {String? filename, MediaType? contentType}) =>
     throw UnsupportedError(
         'MultipartFile is only supported where dart:io is available.');
diff --git a/lib/src/multipart_request.dart b/lib/src/multipart_request.dart
index 7e5469b29f..faacd0b505 100644
--- a/lib/src/multipart_request.dart
+++ b/lib/src/multipart_request.dart
@@ -76,7 +76,7 @@ class MultipartRequest extends BaseRequest {
   }
 
   @override
-  set contentLength(int value) {
+  set contentLength(int? value) {
     throw UnsupportedError('Cannot set the contentLength property of '
         'multipart requests.');
   }
@@ -135,7 +135,7 @@ class MultipartRequest extends BaseRequest {
         'content-disposition: form-data; name="${_browserEncode(file.field)}"';
 
     if (file.filename != null) {
-      header = '$header; filename="${_browserEncode(file.filename)}"';
+      header = '$header; filename="${_browserEncode(file.filename!)}"';
     }
     return '$header\r\n\r\n';
   }
diff --git a/lib/src/request.dart b/lib/src/request.dart
index d882d88cf1..bbb8448abe 100644
--- a/lib/src/request.dart
+++ b/lib/src/request.dart
@@ -22,7 +22,7 @@ class Request extends BaseRequest {
   int get contentLength => bodyBytes.length;
 
   @override
-  set contentLength(int value) {
+  set contentLength(int? value) {
     throw UnsupportedError('Cannot set the contentLength property of '
         'non-streaming Request objects.');
   }
@@ -50,10 +50,10 @@ class Request extends BaseRequest {
   /// charset parameter on that header.
   Encoding get encoding {
     if (_contentType == null ||
-        !_contentType.parameters.containsKey('charset')) {
+        !_contentType!.parameters.containsKey('charset')) {
       return _defaultEncoding;
     }
-    return requiredEncodingForCharset(_contentType.parameters['charset']);
+    return requiredEncodingForCharset(_contentType!.parameters['charset']!);
   }
 
   set encoding(Encoding value) {
@@ -151,14 +151,18 @@ class Request extends BaseRequest {
   }
 
   /// The `Content-Type` header of the request (if it exists) as a [MediaType].
-  MediaType get _contentType {
+  MediaType? get _contentType {
     var contentType = headers['content-type'];
     if (contentType == null) return null;
     return MediaType.parse(contentType);
   }
 
-  set _contentType(MediaType value) {
-    headers['content-type'] = value.toString();
+  set _contentType(MediaType? value) {
+    if (value == null) {
+      headers.remove('content-type');
+    } else {
+      headers['content-type'] = value.toString();
+    }
   }
 
   /// Throw an error if this request has been finalized.
diff --git a/lib/src/response.dart b/lib/src/response.dart
index a88669eca2..01899887a7 100644
--- a/lib/src/response.dart
+++ b/lib/src/response.dart
@@ -29,11 +29,11 @@ class Response extends BaseResponse {
 
   /// Creates a new HTTP response with a string body.
   Response(String body, int statusCode,
-      {BaseRequest request,
+      {BaseRequest? request,
       Map<String, String> headers = const {},
       bool isRedirect = false,
       bool persistentConnection = true,
-      String reasonPhrase})
+      String? reasonPhrase})
       : this.bytes(_encodingForHeaders(headers).encode(body), statusCode,
             request: request,
             headers: headers,
@@ -43,11 +43,11 @@ class Response extends BaseResponse {
 
   /// Create a new HTTP response with a byte array body.
   Response.bytes(List<int> bodyBytes, int statusCode,
-      {BaseRequest request,
+      {BaseRequest? request,
       Map<String, String> headers = const {},
       bool isRedirect = false,
       bool persistentConnection = true,
-      String reasonPhrase})
+      String? reasonPhrase})
       : bodyBytes = toUint8List(bodyBytes),
         super(statusCode,
             contentLength: bodyBytes.length,
diff --git a/lib/src/streamed_response.dart b/lib/src/streamed_response.dart
index a11386e8cb..e082dced0e 100644
--- a/lib/src/streamed_response.dart
+++ b/lib/src/streamed_response.dart
@@ -19,12 +19,12 @@ class StreamedResponse extends BaseResponse {
   ///
   /// [stream] should be a single-subscription stream.
   StreamedResponse(Stream<List<int>> stream, int statusCode,
-      {int contentLength,
-      BaseRequest request,
+      {int? contentLength,
+      BaseRequest? request,
       Map<String, String> headers = const {},
       bool isRedirect = false,
       bool persistentConnection = true,
-      String reasonPhrase})
+      String? reasonPhrase})
       : stream = toByteStream(stream),
         super(statusCode,
             contentLength: contentLength,
diff --git a/lib/src/utils.dart b/lib/src/utils.dart
index 9d0648e359..e79108e88a 100644
--- a/lib/src/utils.dart
+++ b/lib/src/utils.dart
@@ -12,11 +12,11 @@ import 'byte_stream.dart';
 ///
 ///     mapToQuery({"foo": "bar", "baz": "bang"});
 ///     //=> "foo=bar&baz=bang"
-String mapToQuery(Map<String, String> map, {Encoding encoding}) {
+String mapToQuery(Map<String, String> map, {Encoding? encoding}) {
   var pairs = <List<String>>[];
   map.forEach((key, value) => pairs.add([
-        Uri.encodeQueryComponent(key, encoding: encoding),
-        Uri.encodeQueryComponent(value, encoding: encoding)
+        Uri.encodeQueryComponent(key, encoding: encoding ?? utf8),
+        Uri.encodeQueryComponent(value, encoding: encoding ?? utf8)
       ]));
   return pairs.map((pair) => '${pair[0]}=${pair[1]}').join('&');
 }
@@ -25,7 +25,7 @@ String mapToQuery(Map<String, String> map, {Encoding encoding}) {
 ///
 /// Returns [fallback] if [charset] is null or if no [Encoding] was found that
 /// corresponds to [charset].
-Encoding encodingForCharset(String charset, [Encoding fallback = latin1]) {
+Encoding encodingForCharset(String? charset, [Encoding fallback = latin1]) {
   if (charset == null) return fallback;
   return Encoding.getByName(charset) ?? fallback;
 }
diff --git a/pubspec.yaml b/pubspec.yaml
index 07fffd3ca4..ec72d6e8c8 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,15 +1,22 @@
 name: http
-version: 0.12.2
+version: 0.13.0-nullsafety-dev
 homepage: https://github.com/dart-lang/http
 description: A composable, multi-platform, Future-based API for HTTP requests.
 
 environment:
-  sdk: ">=2.4.0 <3.0.0"
+  sdk: '>=2.10.0-2.0.dev <2.11.0'
 
+# Cannot be published until null safety ships
+publish_to: none
 dependencies:
-  http_parser: ">=0.0.1 <4.0.0"
-  path: ">=0.9.0 <2.0.0"
-  pedantic: "^1.0.0"
+  http_parser: ^3.2.0-nullsafety
+  meta: ^1.3.0-nullsafety.3
+  path: ^1.8.0-nullsafety.1
+  pedantic: ^1.10.0-nullsafety
 
 dev_dependencies:
-  test: ^1.3.0
+  test: ^1.16.0-nullsafety.4
+
+dependency_overrides:
+  http_parser:
+    git: https://github.com/dart-lang/http_parser
diff --git a/test/io/multipart_test.dart b/test/io/multipart_test.dart
index 9128b2e4b9..f2333f5322 100644
--- a/test/io/multipart_test.dart
+++ b/test/io/multipart_test.dart
@@ -13,7 +13,7 @@ import 'package:test/test.dart';
 import 'utils.dart';
 
 void main() {
-  Directory tempDir;
+  late Directory tempDir;
   setUp(() {
     tempDir = Directory.systemTemp.createTempSync('http_test_');
   });
diff --git a/test/io/utils.dart b/test/io/utils.dart
index d057fa4c28..7ad3325f8c 100644
--- a/test/io/utils.dart
+++ b/test/io/utils.dart
@@ -14,10 +14,10 @@ import 'package:test/test.dart';
 export '../utils.dart';
 
 /// The current server instance.
-HttpServer _server;
+HttpServer? _server;
 
 /// The URL for the current server instance.
-Uri get serverUrl => Uri.parse('http://localhost:${_server.port}');
+Uri get serverUrl => Uri.parse('http://localhost:${_server!.port}');
 
 /// Starts a new HTTP server.
 Future<void> startServer() async {
@@ -78,7 +78,7 @@ Future<void> startServer() async {
         requestBody = null;
       } else if (request.headers.contentType?.charset != null) {
         var encoding =
-            requiredEncodingForCharset(request.headers.contentType.charset);
+            requiredEncodingForCharset(request.headers.contentType!.charset!);
         requestBody = encoding.decode(requestBodyBytes);
       } else {
         requestBody = requestBodyBytes;
@@ -109,7 +109,7 @@ Future<void> startServer() async {
 /// Stops the current HTTP server.
 void stopServer() {
   if (_server != null) {
-    _server.close();
+    _server!.close();
     _server = null;
   }
 }
diff --git a/test/utils.dart b/test/utils.dart
index 290678f081..ea7cbeb676 100644
--- a/test/utils.dart
+++ b/test/utils.dart
@@ -48,7 +48,7 @@ class _Parse extends Matcher {
   _Parse(this._matcher);
 
   @override
-  bool matches(item, Map matchState) {
+  bool matches(Object? item, Map matchState) {
     if (item is String) {
       dynamic parsed;
       try {
@@ -83,7 +83,7 @@ class _BodyMatches extends Matcher {
   _BodyMatches(this._pattern);
 
   @override
-  bool matches(item, Map matchState) {
+  bool matches(Object? item, Map matchState) {
     if (item is http.MultipartRequest) {
       return completes.matches(_checks(item), matchState);
     }
@@ -94,8 +94,8 @@ class _BodyMatches extends Matcher {
   Future<void> _checks(http.MultipartRequest item) async {
     var bodyBytes = await item.finalize().toBytes();
     var body = utf8.decode(bodyBytes);
-    var contentType = MediaType.parse(item.headers['content-type']);
-    var boundary = contentType.parameters['boundary'];
+    var contentType = MediaType.parse(item.headers['content-type']!);
+    var boundary = contentType.parameters['boundary']!;
     var expected = cleanUpLiteral(_pattern)
         .replaceAll('\n', '\r\n')
         .replaceAll('{{boundary}}', boundary);