How to integrate the captcha

<div id="captcha"></div>

<script>
  function onCaptchaSolved(token) {
    // send the token to your server for verification
    fetch('/my-backend/verify', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ token })
    });
  }
</script>

<script src="http://jkcaptcha.we4.online/js/captcha/widget.js"
        data-key='jcv4w_WIDGET_KEY'
        data-target="#captcha"
        data-callback="onCaptchaSolved"></script>

Attributes: data-key — the public widget key (from the panel), data-target — the container selector, data-callback — the name of the global function that receives the token. If the callback is omitted, a jvc4-solved event with detail.token is dispatched on the container.

C# / ASP.NET

using var http = new HttpClient();
http.DefaultRequestHeaders.Add("X-Api-Key", "jcv4_YOUR_SECRET_KEY");
var r = await http.GetFromJsonAsync<VerifyResponse>(
    "http://jkcaptcha.we4.online/api/v1/verify?token=" + Uri.EscapeDataString(token));
if (r is { valid: true }) { /* human */ }

record VerifyResponse(bool valid);

Node.js

const r = await fetch(
  "http://jkcaptcha.we4.online/api/v1/verify?token=" + encodeURIComponent(token),
  { headers: { "X-Api-Key": "jcv4_YOUR_SECRET_KEY" } }
);
const { valid } = await r.json();
if (valid) { /* human */ }

PHP

$ch = curl_init("http://jkcaptcha.we4.online/api/v1/verify?token=" . urlencode($token));
curl_setopt($ch, CURLOPT_HTTPHEADER, ["X-Api-Key: jcv4_YOUR_SECRET_KEY"]);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$res = json_decode(curl_exec($ch), true);
if (!empty($res["valid"])) { /* human */ }

If you do not want to show the captcha to everyone, ask the service for a verdict based on passive page signals:

POST http://jkcaptcha.we4.online/api/v1/risk
X-Api-Key: jcv4_YOUR_SECRET_KEY
{ "webDriver": false, "hw": 8, "screenW": 1920, "lang": "ru", "elapsedMs": 4000, "moves": 120 }

→ { "score": 0, "verdict": "human", "flags": [] }

Verdicts: human (the captcha may be skipped), suspicious, bot. See the API reference for details.

• Frames: up to 40 requests/sec (the client polls ~30/sec; 204 is returned when nothing changed).
• Input: up to 40/sec; solve attempt (release) — at most once per second.
• Captcha = session: you have 30 to 60 seconds to solve it, then the session ends and the client creates a new one automatically.
• A page keeps the same captcha until it is solved. When the wait timeout expires (300 seconds) the server forcibly closes the page sessions and responds with 410 — the client shows “The session was forcibly terminated, please try again” and stops.
• The token after solving is valid for 300 seconds.