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Is there a maximum size for an HTTP POST? And if there is a max size, is it determined by the protocol or is it at the discretion of the server?

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4 Answers 4

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The HTTP specification doesn't impose a specific size limit for posts. They will usually be limited by either the web server or the programming technology used to process the form submission.

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No limit by specification. The limit is MIN(browser_limit,server_limit).

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  • Is it possible to increase the brower_limit using some flags?
    – rbansal
    Nov 25, 2022 at 9:02
  • @rbansal that depends on the browser!
    – Gwyneth Llewelyn
    Nov 9 at 18:33
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The specifications of the POST method do not impose any limit on the size of data, but both the web servers and the browsers will set their own limits.

For example:

Internet Explorer: 2 GB
Firefox: 2 GB
Chrome: 4 GB
Opera: 4 GB

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    Is motobit Spam-link?
    – Per G
    Oct 5, 2018 at 11:04
  • It would be nice to find a good reference for the above limits; I searched a bit but couldn't find any. Also, it would be nice to add examples for web servers as well!
    – Gwyneth Llewelyn
    Nov 9 at 18:59
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I don't think that there is a specific limit in the protocol, BUT there are cases where things get squirrelly if you're transferring huge files. It depends on the size of the file as to what may work a little better for your specific case. There's not any support for checking that the file wasn't corrupted in transfer, for example, unlike using something like a torrent for the transfer.

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    If TCP does its job, the file should be intact.
    – Justin Scott
    Jun 14, 2010 at 17:24
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    If TCP does its job, we wouldn't need md5 sums to verify ISO images and other large files :-)
    – Bart Silverstrim
    Jun 14, 2010 at 18:08
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    The md5 sums are used to check if source file matches the publisher content file to avoid fakes. TCP does have a package check and chance of error pass without detections is minimum.
    – cavila
    Aug 20, 2014 at 19:22
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    Note: md5 is not collision resistant anymore. Don't trust md5sums to verify the creator of a file.
    – Florian Wendelborn
    Aug 30, 2016 at 17:31
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    @cavila: The TCP check is a 32 bits checksum, so we can quantify that chance: it's 1 in 2^32 per packet. Of course, most packets aren't faulty to begin with.
    – MSalters
    Apr 6, 2017 at 8:33

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