multipart/form-data

What is multipart/form-data?

multipart/form-data is a content type used in HTTP requests for sending binary data like files alongside regular form fields.

For example, submitting the following HTML form:

Can result in the following HTTP request:

POST /submit.php HTTP/1.1
Host: sajad.local:8000
Connection: keep-alive
Content-Length: 417374
Origin: http://sajad.local:8000
Content-Type: multipart/form-data; boundary=----WebKitFormBoundary3hPnbQmTWdhIF3aw
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/136.0.0.0 Safari/537.36

------WebKitFormBoundary3hPnbQmTWdhIF3aw
Content-Disposition: form-data; name="name"

Sajad
------WebKitFormBoundary3hPnbQmTWdhIF3aw
Content-Disposition: form-data; name="age"

31
------WebKitFormBoundary3hPnbQmTWdhIF3aw
Content-Disposition: form-data; name="photo"; filename="My picture.png"
Content-Type: image/png

�PNG

   
IHDR         {C�    cHRM  z&  ��  �   ��  u0  �`  :�  p��Q<   bKGD � � �����   	pHYs  !7  !8����   tIME� ($w  � IDATxڄ�G�%Y��b�Rw���_�M�6�
��Loz~�L7�̯ò[�"�z�@�*�fVU�Ȍ�����,���s�z��D���5;Dϧ\��������HDD$���CD�_�����zz'?)^ADD@ A!� A!���sRI!$��CQ ���-��(P
� <�?"��x������O<�p����l������1ĵ����r	!��{/����G����!��_'�{ty�_?!! yo�@�!��!�(�6&]���
	�6�o$�te�u������gƯ�Hb����z�z�.�����t�!�Hrq�⊥S�����>,����!�9I���<rH�����u@D^>� ���(����d* k�B)����{�WJ!��>� 
------WebKitFormBoundary3hPnbQmTWdhIF3aw--

Note that I have removed over two thousand lines of the actual HTTP request from above to shorten the example. In reality, a HTTP multipart/form-data request that contains a file will send the file as binary data in the request so the actual request can be thousands of lines.

Here’s the format of a multipart/form-data request:

Links

• Returning Values from Forms: multipart/form-data – RFC 7578