---
name: "curl_mime_type"
section: "3"
platform: "linux"
package: "curl"
version: "8.23.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux", "macos"]
url: "https://new.carta.tech/curl_mime_type"
---

# curl\_mime\_type(3)

set a mime part's content type

## NAME

curl\_mime\_type - set a mime part's content type

## SYNOPSIS

```
#include <curl/curl.h>
CURLcode curl_mime_type(curl_mimepart *part, const char *mimetype);
```

## DESCRIPTION

*[curl\_mime\_type(3)](/curl_mime_type/3.md)* sets a mime part's content type.

*part* is the part's handle to assign the content type to.

*mimetype* points to the null-terminated file mime type string; it may be set to NULL to remove a previously attached mime type.

The mime type string is copied into the part, thus the associated storage may safely be released or reused after call. Setting a part's type multiple times is valid: only the value set by the last call is retained.

In the absence of a mime type and if needed by the protocol specifications, a default mime type is determined by the context:

\- If set as a custom header, use this value.

\- application/form-data for an HTTP form post.

\- If a remote filename is set, the mime type is taken from the filename extension, or application/octet-stream by default.

\- For a multipart part, multipart/mixed.

\- text/plain in other cases.

## PROTOCOLS

This functionality affects http, imap and smtp

## EXAMPLE

```
int main(void)
{
  curl_mime *mime;
  curl_mimepart *part;
  CURL *curl = curl_easy_init();
  if(curl) {
    /* create a mime handle */
    mime = curl_mime_init(curl);
    /* add a part */
    part = curl_mime_addpart(mime);
    /* get data from this file */
    curl_mime_filedata(part, "image.png");
    /* content-type for this part */
    curl_mime_type(part, "image/png");
    /* set name */
    curl_mime_name(part, "image");
}
}
```

## AVAILABILITY

Added in curl 7.56.0

## RETURN VALUE

This function returns a CURLcode indicating success or error.

CURLE\_OK (0) means everything was OK, non-zero means an error occurred, see *[libcurl-errors(3)](/libcurl-errors/3.md)*. If *[CURLOPT\_ERRORBUFFER(3)](/CURLOPT_ERRORBUFFER/3.md)* was set with *[curl\_easy\_setopt(3)](/curl_easy_setopt/3.md)* there can be an error message stored in the error buffer when non-zero is returned.

## SEE ALSO

[**curl\_mime\_addpart**(3)](/curl_mime_addpart/3.md), [**curl\_mime\_data**(3)](/curl_mime_data/3.md), [**curl\_mime\_name**(3)](/curl_mime_name/3.md)