curl\_easy\_unescape(3) Library Functions Manual curl\_easy\_unescape(3)

# [NAME](#NAME)

curl\_easy\_unescape - URL decode a string

# [SYNOPSIS](#SYNOPSIS)

```
#include <curl/curl.h>
char *curl_easy_unescape(CURL *curl, const char *input,


                         int inlength, int *outlength);
```

# [DESCRIPTION](#DESCRIPTION)

This function converts the URL encoded string **input** to a "plain string" and returns that in an allocated memory area. All input characters that are URL encoded (%XX where XX is a two-digit hexadecimal number) are converted to their binary versions. Although not constrained by its type, the returned data may not be altered.

If the **length** argument is set to 0 (zero), [*curl\_easy\_unescape(3)*](/man/os/curl/curl_easy_unescape.3) uses strlen() on **input** to find out the size.

If **outlength** is non-NULL, the function writes the length of the returned string in the integer it points to. This allows proper handling even for strings containing %00. Since this is a pointer to an *int* type, it can only return a value up to *INT\_MAX* so no longer string can be returned in this parameter.

Since 7.82.0, the **curl** parameter is ignored. Prior to that there was per-handle character conversion support for some old operating systems such as TPF, but it was otherwise ignored.

You must [*curl\_free(3)*](/man/os/curl/curl_free.3) the returned string when you are done with it.

# [PROTOCOLS](#PROTOCOLS)

This functionality affects all supported protocols

# [EXAMPLE](#EXAMPLE)

```
int main(void)
{


  CURL *curl = curl_easy_init();


  if(curl) {


    int decodelen;


    char *decoded = curl_easy_unescape(curl, "%63%75%72%6c", 12, &decodelen);


    if(decoded) {


      /* do not assume printf() works on the decoded data */


      printf("Decoded: ");


      /* ... */


      curl_free(decoded);


    }


    curl_easy_cleanup(curl);


  }
}
```

# [AVAILABILITY](#AVAILABILITY)

Added in curl 7.15.4

# [RETURN VALUE](#RETURN_VALUE)

A pointer to a null-terminated string or NULL if it failed.

# [SEE ALSO](#SEE_ALSO)

[**curl\_easy\_escape**(3)](/man/os/curl/curl_easy_escape.3), [**curl\_url\_get**(3)](/man/os/curl/curl_url_get.3)

2026-09-24 libcurl

---

Document: curl_easy_unescape(3) from curl 8.22.0-r3 (Chainguard OS)
Source: https://github.com/curl/curl.git