How to Reduce PDF File Size in C/C++

1 min readApr 5, 2021


While large PDF files are an inevitability for certain types of business documents, processing and loading times between programs and computers can run rather long. Utilizing the following API in C/C++ will allow you to reduce the file size of a PDF by optimizing its content.

To use the API, we first need to install libcurl into the project:


Next, we simply need to input the target file and the API key into the example code below:

CURL *curl;
CURLcode res;
curl = curl_easy_init();
if(curl) {
curl_easy_setopt(curl, CURLOPT_CUSTOMREQUEST, "POST");
curl_easy_setopt(curl, CURLOPT_URL, "");
curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
curl_easy_setopt(curl, CURLOPT_DEFAULT_PROTOCOL, "https");
struct curl_slist *headers = NULL;
headers = curl_slist_append(headers, "Content-Type: multipart/form-data");
headers = curl_slist_append(headers, "Apikey: YOUR-API-KEY-HERE");
curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
curl_mime *mime;
curl_mimepart *part;
mime = curl_mime_init(curl);
part = curl_mime_addpart(mime);
curl_mime_name(part, "inputFile");
curl_mime_filedata(part, "/path/to/file");
curl_easy_setopt(curl, CURLOPT_MIMEPOST, mime);
res = curl_easy_perform(curl);

At the end of this quick process, you’ll receive a condensed PDF file for download. Visit the Cloudmersive website to retrieve your free API key and gain access to 800 monthly calls across our library of APIs.




There’s an API for that. Cloudmersive is a leader in Highly Scalable Cloud APIs.