diff --git a/seed/php-sdk/file-upload/src/Core/MultipartApiRequest.php b/seed/php-sdk/file-upload/src/Core/MultipartApiRequest.php
new file mode 100644
index 00000000000..38df42ad366
--- /dev/null
+++ b/seed/php-sdk/file-upload/src/Core/MultipartApiRequest.php
@@ -0,0 +1,27 @@
+<?php
+
+
+namespace Seed\Core;
+
+class MultipartApiRequest extends BaseApiRequest
+{
+    /**
+     * @param string $baseUrl The base URL for the request
+     * @param string $path The path for the request
+     * @param HttpMethod $method The HTTP method for the request
+     * @param array<string, string> $headers Additional headers for the request (optional)
+     * @param array<string, mixed> $query Query parameters for the request (optional)
+     * @param ?MultipartFormData $body The multipart form data for the request (optional)
+     */
+    public function __construct(
+        string $baseUrl,
+        string $path,
+        HttpMethod $method,
+        array $headers = [],
+        array $query = [],
+        public readonly ?MultipartFormData $body = null
+    )
+    {
+        parent::__construct($baseUrl, $path, $method, $headers, $query);
+    }
+}
diff --git a/seed/php-sdk/file-upload/src/Core/MultipartFormData.php b/seed/php-sdk/file-upload/src/Core/MultipartFormData.php
new file mode 100644
index 00000000000..24542346bd1
--- /dev/null
+++ b/seed/php-sdk/file-upload/src/Core/MultipartFormData.php
@@ -0,0 +1,62 @@
+<?php
+
+namespace Seed\Core;
+
+use Psr\Http\Message\StreamInterface;
+
+class MultipartFormData
+{
+    /**
+     * @var array<MultipartFormDataPart>
+     */
+    private array $parts = [];
+
+    /**
+     * Adds a new part to the multipart form data.
+     *
+     * @param string $name
+     * @param string|int|bool|float|StreamInterface $value
+     * @param ?string $contentType
+     */
+    public function add(
+        string $name,
+        string|int|bool|float|StreamInterface $value,
+        ?string $contentType = null,
+    ): void
+    {
+        $headers = $contentType != null ? ['Content-Type' => $contentType] : null;
+        self::addPart(
+            new MultipartFormDataPart(
+                name: $name,
+                contents: $value,
+                headers: $headers,
+            )
+        );
+    }
+
+    /**
+     * Adds a new part to the multipart form data.
+     *
+     * @param MultipartFormDataPart $part
+     */
+    public function addPart(MultipartFormDataPart $part): void
+    {
+        $this->parts[] = $part;
+    }
+
+    /**
+     * Converts the multipart form data into an array suitable
+     * for Guzzle's multipart form data.
+     *
+     * @return array<array{
+     *     name: string,
+     *     contents: StreamInterface,
+     *     filename?: string,
+     *     headers?: array<string, string>
+     * }>
+     */
+    public function toArray(): array
+    {
+        return array_map(fn($part) => $part->toArray(), $this->parts);
+    }
+}
diff --git a/seed/php-sdk/file-upload/src/Core/MultipartFormDataPart.php b/seed/php-sdk/file-upload/src/Core/MultipartFormDataPart.php
new file mode 100644
index 00000000000..5af660590c0
--- /dev/null
+++ b/seed/php-sdk/file-upload/src/Core/MultipartFormDataPart.php
@@ -0,0 +1,76 @@
+<?php
+
+namespace Seed\Core;
+
+use GuzzleHttp\Psr7\Utils;
+use Psr\Http\Message\StreamInterface;
+
+class MultipartFormDataPart
+{
+    /**
+     * @var string
+     */
+    private string $name;
+
+    /**
+     * @var StreamInterface
+     */
+    private StreamInterface $contents;
+
+    /**
+     * @var ?string
+     */
+    private ?string $filename;
+
+    /**
+     * @var ?array<string, string>
+     */
+    private ?array $headers;
+
+    /**
+     * @param string $name
+     * @param string|bool|float|int|StreamInterface $contents
+     * @param ?string $filename
+     * @param ?array<string, string> $headers
+     */
+    public function __construct(
+        string $name,
+        string|bool|float|int|StreamInterface $contents,
+        ?string $filename = null,
+        ?array $headers = null
+    ) {
+        $this->name = $name;
+        $this->contents = Utils::streamFor($contents);
+        $this->filename = $filename;
+        $this->headers = $headers;
+    }
+
+    /**
+     * Converts the multipart form data part into an array suitable
+     * for Guzzle's multipart form data.
+     *
+     * @return array{
+     *     name: string,
+     *     contents: StreamInterface,
+     *     filename?: string,
+     *     headers?: array<string, string>
+     * }
+     */
+    public function toArray(): array
+    {
+        $formData = [
+            'name' => $this->name,
+            'contents' => $this->contents,
+        ];
+
+        if ($this->filename != null) {
+            $formData['filename'] = $this->filename;
+        }
+
+        if ($this->headers != null) {
+            $formData['headers'] = $this->headers;
+        }
+
+        return $formData;
+    }
+}
\ No newline at end of file
diff --git a/seed/php-sdk/file-upload/src/Core/RawClient.php b/seed/php-sdk/file-upload/src/Core/RawClient.php
index 1c0e42bf650..ea9ffad01b8 100644
--- a/seed/php-sdk/file-upload/src/Core/RawClient.php
+++ b/seed/php-sdk/file-upload/src/Core/RawClient.php
@@ -4,6 +4,7 @@
 
 use GuzzleHttp\Client;
 use GuzzleHttp\ClientInterface;
+use GuzzleHttp\Psr7\MultipartStream;
 use GuzzleHttp\Psr7\Request;
 use GuzzleHttp\Psr7\Utils;
 use InvalidArgumentException;
@@ -73,6 +74,11 @@ private function encodeHeaders(
                 $this->headers,
                 $request->headers
             ),
+            MultipartApiRequest::class => array_merge(
+                ["Content-Type" => "multipart/form-data"],
+                $this->headers,
+                $request->headers
+            ),
             default => throw new InvalidArgumentException('Unsupported request type: ' . get_class($request)),
         };
     }
@@ -82,6 +88,7 @@ private function encodeRequestBody(
     ): ?StreamInterface {
         return match (get_class($request)) {
             JsonApiRequest::class => $request->body != null ? Utils::streamFor(json_encode($request->body)) : null,
+            MultipartApiRequest::class => $request->body != null ? new MultipartStream($request->body->toArray()) : null,
             default => throw new InvalidArgumentException('Unsupported request type: '.get_class($request)),
         };
     }
diff --git a/seed/php-sdk/file-upload/src/Service/Requests/JustFileRequet.php b/seed/php-sdk/file-upload/src/Service/Requests/JustFileRequet.php
index e5aa46978ba..2baf4548714 100644
--- a/seed/php-sdk/file-upload/src/Service/Requests/JustFileRequet.php
+++ b/seed/php-sdk/file-upload/src/Service/Requests/JustFileRequet.php
@@ -2,6 +2,23 @@
 
 namespace Seed\Service\Requests;
 
+use Seed\Utils\File;
+
 class JustFileRequet
 {
+    /**
+     * @var File $foo
+     */
+    public File $file;
+
+    /**
+     * @param array{
+     *   file: File,
+     * } $values
+     */
+    public function __construct(
+        array $values,
+    ) {
+        $this->file = $values['file'];
+    }
 }
diff --git a/seed/php-sdk/file-upload/src/Service/Requests/JustFileWithQueryParamsRequet.php b/seed/php-sdk/file-upload/src/Service/Requests/JustFileWithQueryParamsRequet.php
index 0f84cbed492..77fa7b6317e 100644
--- a/seed/php-sdk/file-upload/src/Service/Requests/JustFileWithQueryParamsRequet.php
+++ b/seed/php-sdk/file-upload/src/Service/Requests/JustFileWithQueryParamsRequet.php
@@ -2,6 +2,8 @@
 
 namespace Seed\Service\Requests;
 
+use Seed\Utils\File;
+
 class JustFileWithQueryParamsRequet
 {
     /**
@@ -29,6 +31,11 @@ class JustFileWithQueryParamsRequet
      */
     public array $optionalListOfStrings;
 
+    /**
+     * @var File $file
+     */
+    public File $file;
+
     /**
      * @param array{
      *   maybeString?: ?string,
@@ -36,6 +43,7 @@ class JustFileWithQueryParamsRequet
      *   maybeInteger?: ?int,
      *   listOfStrings: array<string>,
      *   optionalListOfStrings: array<?string>,
+     *   file: File,
      * } $values
      */
     public function __construct(
@@ -46,5 +54,6 @@ public function __construct(
         $this->maybeInteger = $values['maybeInteger'] ?? null;
         $this->listOfStrings = $values['listOfStrings'];
         $this->optionalListOfStrings = $values['optionalListOfStrings'];
+        $this->file = $values['file'];
     }
 }
diff --git a/seed/php-sdk/file-upload/src/Service/Requests/MyRequest.php b/seed/php-sdk/file-upload/src/Service/Requests/MyRequest.php
index b0ac95c364b..e4fc64e1cbc 100644
--- a/seed/php-sdk/file-upload/src/Service/Requests/MyRequest.php
+++ b/seed/php-sdk/file-upload/src/Service/Requests/MyRequest.php
@@ -2,6 +2,102 @@
 
 namespace Seed\Service\Requests;
 
+use Seed\Utils\File;
+use Seed\Service\Types\MyObject;
+use Seed\Service\Types\ObjectType;
+
 class MyRequest
 {
-}
+    /**
+     * @var ?string $maybeString
+     */
+    public ?string $maybeString;
+
+    /**
+     * @var int $integer
+     */
+    public int $integer;
+
+    /**
+     * @var File $file
+     */
+    public File $file;
+
+    /**
+     * @var array<File> $fileList
+     */
+    public array $fileList;
+
+    /**
+     * @var ?File $maybeFile
+     */
+    public ?File $maybeFile;
+
+    /**
+     * @var ?array<File> $maybeFileList
+     */
+    public ?array $maybeFileList;
+
+    /**
+     * @var ?int $maybeInteger
+     */
+    public ?int $maybeInteger;
+
+    /**
+     * @var ?array<string> $optionalListOfStrings
+     */
+    public ?array $optionalListOfStrings;
+
+    /**
+     * @var array<MyObject> $listOfObjects
+     */
+    public array $listOfObjects;
+
+    /**
+     * @var mixed $optionalMetadata
+     */
+    public $optionalMetadata;
+
+    /**
+     * @var ?ObjectType $optionalObjectType
+     */
+    public ?ObjectType $optionalObjectType;
+
+    /**
+     * @var ?string $optionalId
+     */
+    public ?string $optionalId;
+
+    /**
+     * @param array{
+     *   maybeString?: ?string,
+     *   integer: int,
+     *   file: File,
+     *   fileList: array<File>,
+     *   maybeFile?: ?File,
+     *   maybeFileList?: ?array<File>,
+     *   maybeInteger?: ?int,
+     *   optionalListOfStrings?: ?array<string>,
+     *   listOfObjects: array<MyObject>,
+     *   optionalMetadata?: mixed,
+     *   optionalObjectType?: ?ObjectType,
+     *   optionalId?: ?string,
+     * } $values
+     */
+    public function __construct(
+        array $values,
+    ) {
+        $this->maybeString = $values['maybeString'] ?? null;
+        $this->integer = $values['integer'];
+        $this->file = $values['file'];
+        $this->fileList = $values['fileList'];
+        $this->maybeFile = $values['maybeFile'] ?? null;
+        $this->maybeFileList = $values['maybeFileList'] ?? null;
+        $this->maybeInteger = $values['maybeInteger'] ?? null;
+        $this->optionalListOfStrings = $values['optionalListOfStrings'] ?? null;
+        $this->listOfObjects = $values['listOfObjects'];
+        $this->optionalMetadata = $values['optionalMetadata'] ?? null;
+        $this->optionalObjectType = $values['optionalObjectType'] ?? null;
+        $this->optionalId = $values['optionalId'] ?? null;
+    }
+}
\ No newline at end of file
diff --git a/seed/php-sdk/file-upload/src/Service/Requests/WithContentTypeRequest.php b/seed/php-sdk/file-upload/src/Service/Requests/WithContentTypeRequest.php
index f59b677f4f2..60bd616f822 100644
--- a/seed/php-sdk/file-upload/src/Service/Requests/WithContentTypeRequest.php
+++ b/seed/php-sdk/file-upload/src/Service/Requests/WithContentTypeRequest.php
@@ -2,6 +2,38 @@
 
 namespace Seed\Service\Requests;
 
+use Seed\Utils\File;
+use Seed\Service\Types\MyObject;
+
 class WithContentTypeRequest
 {
+    /**
+     * @var File $file
+     */
+    public File $file;
+
+    /**
+     * @var string $foo
+     */
+    public string $foo;
+
+    /**
+     * @var MyObject $bar
+     */
+    public MyObject $bar;
+
+    /**
+     * @param array{
+     *   file: File,
+     *   foo: string,
+     *   bar: MyObject,
+     * } $values
+     */
+    public function __construct(
+        array $values,
+    ) {
+        $this->file = $values['file'];
+        $this->foo = $values['foo'];
+        $this->bar = $values['bar'];
+    }
 }
diff --git a/seed/php-sdk/file-upload/src/Service/ServiceClient.php b/seed/php-sdk/file-upload/src/Service/ServiceClient.php
index e9fa9a8e081..cf1c0d7135e 100644
--- a/seed/php-sdk/file-upload/src/Service/ServiceClient.php
+++ b/seed/php-sdk/file-upload/src/Service/ServiceClient.php
@@ -2,6 +2,10 @@
 
 namespace Seed\Service;
 
+use Exception;
+use Seed\Core\MultipartApiRequest;
+use Seed\Core\MultipartFormData;
+use Seed\Core\MultipartFormDataPart;
 use Seed\Core\RawClient;
 use Seed\Service\Requests\MyRequest;
 use Seed\Exceptions\SeedException;
@@ -39,12 +43,31 @@ public function __construct(
      */
     public function post(MyRequest $request, ?array $options = null): void
     {
+        $body = new MultipartFormData();
+        if ($request->maybeString != null) {
+            $body->add(name: 'maybeString', value: $request->maybeString);
+        }
+        $body->add(name: 'integer', value: $request->integer);
+        $body->addPart($request->file->toMultipartFormDataPart('file'));
+        foreach ($request->fileList as $file) {
+            $body->addPart($file->toMultipartFormDataPart('fileList'));
+        }
+        if ($request->maybeFile != null) {
+            $body->addPart($request->maybeFile->toMultipartFormDataPart('maybeFile'));
+        }
+        if ($request->maybeFileList != null) {
+            foreach ($request->fileList as $file) {
+                $body->addPart($file->toMultipartFormDataPart('maybeFileList'));
+            }
+        }
+
         try {
             $response = $this->client->sendRequest(
-                new JsonApiRequest(
+                new MultipartApiRequest(
                     baseUrl: $this->options['baseUrl'] ?? $this->client->options['baseUrl'] ?? '',
                     path: "",
                     method: HttpMethod::POST,
+                    body: $body,
                 ),
             );
             $statusCode = $response->getStatusCode();
@@ -71,12 +94,16 @@ public function post(MyRequest $request, ?array $options = null): void
      */
     public function justFile(JustFileRequet $request, ?array $options = null): void
     {
+        $body = new MultipartFormData();
+        $body->addPart($request->file->toMultipartFormDataPart('file'));
+
         try {
             $response = $this->client->sendRequest(
                 new JsonApiRequest(
                     baseUrl: $this->options['baseUrl'] ?? $this->client->options['baseUrl'] ?? '',
                     path: "/just-file",
                     method: HttpMethod::POST,
+                    body: $body,
                 ),
             );
             $statusCode = $response->getStatusCode();
@@ -115,6 +142,10 @@ public function justFileWithQueryParams(JustFileWithQueryParamsRequet $request,
         if ($request->optionalListOfStrings != null) {
             $query['optionalListOfStrings'] = $request->optionalListOfStrings;
         }
+
+        $body = new MultipartFormData();
+        $body->addPart($request->file->toMultipartFormDataPart('file'));
+
         try {
             $response = $this->client->sendRequest(
                 new JsonApiRequest(
@@ -122,6 +153,7 @@ public function justFileWithQueryParams(JustFileWithQueryParamsRequet $request,
                     path: "/just-file-with-query-params",
                     method: HttpMethod::POST,
                     query: $query,
+                    body: $body,
                 ),
             );
             $statusCode = $response->getStatusCode();
@@ -148,12 +180,27 @@ public function justFileWithQueryParams(JustFileWithQueryParamsRequet $request,
      */
     public function withContentType(WithContentTypeRequest $request, ?array $options = null): void
     {
+        try {
+            $body = new MultipartFormData();
+            $body->addPart(
+                $request->file->toMultipartFormDataPart(
+                    name: 'file',
+                    contentType:'application/octet-stream',
+                ),
+            );
+            $body->add('foo', $request->foo);
+            $body->add('bar', $request->bar->toJson());
+        } catch (Exception $e) {
+            throw new SeedException(message: $e->getMessage(), previous: $e);
+        }
+
         try {
             $response = $this->client->sendRequest(
                 new JsonApiRequest(
                     baseUrl: $this->options['baseUrl'] ?? $this->client->options['baseUrl'] ?? '',
                     path: "/with-content-type",
                     method: HttpMethod::POST,
+                    body: $body,
                 ),
             );
             $statusCode = $response->getStatusCode();
diff --git a/seed/php-sdk/file-upload/src/Utils/File.php b/seed/php-sdk/file-upload/src/Utils/File.php
new file mode 100644
index 00000000000..098702d0a62
--- /dev/null
+++ b/seed/php-sdk/file-upload/src/Utils/File.php
@@ -0,0 +1,125 @@
+<?php
+
+namespace Seed\Utils;
+
+use Exception;
+use GuzzleHttp\Psr7\Utils;
+use Psr\Http\Message\StreamInterface;
+use Seed\Core\MultipartFormDataPart;
+
+/**
+ * File is a utility class used to transfer files as multipart form data.
+ */
+class File
+{
+    /** @var StreamInterface */
+    private StreamInterface $stream;
+
+    /** @var ?string */
+    private ?string $filename;
+
+    /** @var ?string */
+    private ?string $contentType;
+
+    /**
+     * @param StreamInterface $stream
+     * @param ?string $filename
+     * @param ?string $contentType
+     */
+    public function __construct(
+        StreamInterface $stream,
+        ?string $filename = null,
+        ?string $contentType = null,
+    ) {
+        $this->filename = $filename;
+        $this->contentType = $contentType;
+        $this->stream = $stream;
+    }
+
+    /**
+     * Creates a File instance from a filepath.
+     *
+     * @param string $filepath
+     * @param ?string $filename
+     * @param ?string $contentType
+     * @return File
+     * @throws Exception
+     */
+    public static function createFromFilepath(
+        string $filepath,
+        ?string $filename = null,
+        ?string $contentType = null,
+    ): File {
+        $resource = fopen($filepath, 'r');
+        if (!$resource) {
+            throw new Exception("Unable to open file $filepath");
+        }
+        $stream = Utils::streamFor($resource);
+        if (!$stream->isReadable()) {
+            throw new Exception("File $filepath is not readable");
+        }
+        return new self(
+            stream: $stream,
+            filename: $filename ?? basename($filepath),
+            contentType: $contentType,
+        );
+    }
+
+    /**
+     * Creates a File instance from a string.
+     *
+     * @param string $content
+     * @param ?string $filename
+     * @param ?string $contentType
+     * @return File
+     */
+    public static function createFromString(
+        string $content,
+        ?string $filename,
+        ?string $contentType = null,
+    ): File {
+        return new self(
+            stream: Utils::streamFor($content),
+            filename: $filename,
+            contentType: $contentType,
+        );
+    }
+
+    /**
+     * Maps this File into a multipart form data part.
+     *
+     * @param string $name The name of the mutlipart form data part.
+     * @param ?string $contentType Overrides the Content-Type associated with the file, if any.
+     * @return MultipartFormDataPart
+     */
+    public function toMultipartFormDataPart(string $name, ?string $contentType = null): MultipartFormDataPart
+    {
+        $contentType ??= $this->contentType;
+        $headers = $contentType != null
+            ? ['Content-Type' => $contentType]
+            : null;
+
+        return new MultipartFormDataPart(
+            name: $name,
+            contents: $this->stream,
+            filename: $this->filename,
+            headers: $headers,
+        );
+    }
+
+    /**
+     * Closes the file stream.
+     */
+    public function close(): void
+    {
+        $this->stream->close();
+    }
+
+    /**
+     * Destructor to ensure stream is closed.
+     */
+    public function __destruct()
+    {
+        $this->close();
+    }
+}