C with libcurl: POST /v1/images on Sume and read the status code

libcurl is the right tool when you embed an image call in a native program or a build step.

The request is the same in every language: POST https://api.sume.com/v1/images with a bearer key from SUME_API_KEY, a JSON body with model, prompt and aspect_ratio, and a client timeout above the route's 30-second wait. The route defaults to mode: "sync", so the status code decides what you do next (docs read 2026-10-07):

Status codes to branch on

C code

Compile with cc gen.c -lcurl -o gen and run SUME_API_KEY=... ./gen. The body goes to stdout by default; the status line goes to stderr.

#include <curl/curl.h>
#include <stdio.h>
#include <stdlib.h>

int main(void) {
  const char *key = getenv("SUME_API_KEY");
  if (!key || !*key) { fprintf(stderr, "SUME_API_KEY missing\n"); return 1; }
  char auth[512];
  snprintf(auth, sizeof auth, "Authorization: Bearer %s", key);
  const char *body = "{\"model\":\"bytedance-seed/seedream-5-lite\","
      "\"prompt\":\"matte ceramic mug on a white sweep, soft shadow\","
      "\"aspect_ratio\":\"16:9\"}";
  curl_global_init(CURL_GLOBAL_DEFAULT);
  CURL *c = curl_easy_init();
  struct curl_slist *h = curl_slist_append(NULL, auth);
  h = curl_slist_append(h, "Content-Type: application/json");
  curl_easy_setopt(c, CURLOPT_URL, "https://api.sume.com/v1/images");
  curl_easy_setopt(c, CURLOPT_HTTPHEADER, h);
  curl_easy_setopt(c, CURLOPT_POSTFIELDS, body);
  curl_easy_setopt(c, CURLOPT_TIMEOUT, 40L);
  CURLcode rc = curl_easy_perform(c);
  long status = 0;
  curl_easy_getinfo(c, CURLINFO_RESPONSE_CODE, &status);
  fprintf(stderr, "\nstatus %ld (200 = done, 202 = follow status_url)\n", status);
  curl_slist_free_all(h);
  curl_easy_cleanup(c);
  curl_global_cleanup();
  return rc == CURLE_OK && (status == 200 || status == 202) ? 0 : 1;
}

Notes

libcurl writes the response body to stdout when no write callback is set, so ./gen > out.json captures the JSON. The status is read after curl_easy_perform with CURLINFO_RESPONSE_CODE.

CURLOPT_TIMEOUT is 40 seconds, above Sume's 30-second sync wait. The exit code is 0 for 200 and 202 and 1 otherwise, so a Makefile or CI step can check it.

One bytedance-seed/seedream-5-lite image is $0.04375 billed (list $0.035 x 1.25). Prices here are Sume's list-times-1.25 figures. The catalog states the billable formula as "list × 1.25 → ceil usd cents", so treat the dollar amounts as the pre-rounding value and read the exact charge from billable_amount_usd_micros in the submit envelope. Failed or cancelled generations are not billed.

Sources: Sume Image API docs and Jobs and results (read 2026-10-07).