Quickstart

This guide will help you integrate CaptchaLa CAPTCHA in 5 minutes.

See it work in 30 seconds

demo-v1.captcha.la — pure HTML + PHP, MIT-licensed, view-source on every page.

• popup.html — popup mode
• float.html — floating widget
• bind.html — bind to button
• inline.html — inline embed
• server-token.html — server-issued token (anti-replay)

1. Create Account

Sign up for a free account in the dashboard

Sign Up Now →

2. Create Application

Create an app in the dashboard to get your App Key

3. Install SDK

Choose your preferred installation method

<!-- CDN loader (recommended): auto-fallback CDN, ~6 KB gzip -->
<script src="https://cdn.captcha-cdn.net/captchala-loader.js"></script>

# or via npm
npm install captchala

4. Initialize CAPTCHA

Initialize the CAPTCHA component in your page

<button id="login-btn">Sign in</button>

<script>
loadCaptchala(function () {
  Captchala.init({
    appKey: 'YOUR_APP_KEY',
    product: 'bind',          // popup | float | bind | embed
    action: 'login',
    lang: 'auto',
  })
  .onSuccess(function (res) {
    // res.token starts with pt_ — POST it to your backend
    submitLogin(res.token);
  })
  .onError(function (err) { console.error(err.message); })
  .bindTo('#login-btn');     // popup/bind use bindTo; float/embed use appendTo
});
</script>

5. Server Verification

Verify the token on your server

POST https://apiv1.captcha.la/v1/validate
X-App-Key: YOUR_APP_KEY
X-App-Secret: YOUR_APP_SECRET
Content-Type: application/json

{ "pass_token": "<from onSuccess>", "client_ip": "<end-user IP>" }

{
  "code": 0,
  "data": {
    "valid": true,
    "action": "login",
    "challenge_id": "ch_xxx",
    "uid": null,
    "client_ip": "1.2.3.4",
    "risk_score": 12
  }
}

WARNING

Always check data.valid === true and data.action matches the scene you expected. Pass tokens are single-use; the same pt_xxx cannot be validated twice.

Server-issued Token Mode (recommended for production)

For sensitive actions (login, register, payment) we recommend the server-issued token flow: your backend first requests a short-lived server_token, which the browser then uses to initialize the CAPTCHA. This prevents abuse from a leaked app_key.

When to use

• Recommended: register, login, password reset, payment, points redemption, and any endpoint an attacker can script.
• Optional: casual public forms, search boxes, and low-value interactions where convenience matters more.

1. Backend issues server_token

Call /v1/server/challenge/issue from your own server, using the X-App-Key and X-App-Secret headers. Never expose these headers to the browser.

# Server-side only — never call this from a browser
curl -X POST https://apiv1.captcha.la/v1/server/challenge/issue \
  -H "X-App-Key: YOUR_APP_KEY" \
  -H "X-App-Secret: YOUR_APP_SECRET" \
  -d "action=login&ttl=300&max_uses=1&bind_ip=1.2.3.4"

# → { "code": 0, "data": { "server_token": "sct_...", "expires_in": 300 } }

2. Frontend renders CaptchaLa with the server_token

Pass the token to your CaptchaLa component. The SDK forwards it to the challenge initialization when initializing the challenge.

// Browser fetches the token from YOUR backend, not from CaptchaLa directly
const { serverToken } = await fetch('/api/captcha/issue').then(r => r.json());

Captchala.init({
  appKey: 'YOUR_APP_KEY',
  serverToken,             // single-use, short-lived
  product: 'popup',
  action: 'login',
})
.appendTo('#captcha-container')
.onSuccess(res => submitForm(res.token));

Security notes

• Never put app_secret in frontend code, mobile apps, or public repositories. It must stay server-side.
• Enable "Require server-issued challenge token" in the dashboard to reject any challenge attempted without a server_token.
• Keep ttl short (300s default, 900s max) and prefer max_uses=1 to reduce the impact of token leakage.

Next steps

• Web SDK
• API Reference