Friendly Captcha API Reference

Solve Friendly Captcha proof-of-work widgets and submit the solution with the protected form.

The Captcha.fun Friendly Captcha API accepts kind, url, siteKey and returns frc-captcha-solution value. Send the API_KEY header, create a solve with POST /v1/request, then poll GET /v2/response/{id} until ready is true.

What you’ll need

Your API key
The URL of the page where the challenge appears
The site key from the page
Optional: friendlyVersion, friendlyCdnOrigin
A proxy, if the result must come from your own IP (friendly_captcha_proxy)

Use kind

Good to Know

Returns frc-captcha-solution for v1 widgets and frc-captcha-response for v2. Set friendlyVersion to the site’s widget line; add -eu for EU-region keys.

Pass friendlyCdnOrigin if the site serves the widget from its own origin instead of the public CDN.

Send the Challenge

Create Solve · POST /v1/request

Send the page details with your API key. You get a solve id back right away.

POSThttps://api.captcha.fun/v1/request

curl -X POST https://api.captcha.fun/v1/request \
  -H "API_KEY: CAPFUN-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX" \
  -H "Content-Type: application/json" \
  -H "Accept: application/json" \
  -d '{
  "kind": "friendly_captcha",
  "url": "https://your-domain.example/login",
  "siteKey": "YOUR_FRIENDLY_CAPTCHA_SITE_KEY"
}'

import requests

response = requests.post(
    "https://api.captcha.fun/v1/request",
    headers={
        "API_KEY": "CAPFUN-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX",
        "Content-Type": "application/json",
        "Accept": "application/json",
    },
    json={"kind": "friendly_captcha", "url": "https://your-domain.example/login", "siteKey": "YOUR_FRIENDLY_CAPTCHA_SITE_KEY"},
)

print(response.status_code, response.json())

const response = await fetch("https://api.captcha.fun/v1/request", {
  method: "POST",
  headers: {
    "API_KEY": "CAPFUN-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX",
    "Content-Type": "application/json",
    "Accept": "application/json"
  },
  body: JSON.stringify({
  "kind": "friendly_captcha",
  "url": "https://your-domain.example/login",
  "siteKey": "YOUR_FRIENDLY_CAPTCHA_SITE_KEY"
})
});

console.log(response.status, await response.json());

Response

Returns the solve id. Use it to get the result.

{
  "id": "550e8400-e29b-41d4-a716-446655440000",
  "message": "Started Solving"
}

{
  "message": "invalid kind"
}

Request fields7 body fields · 3 required

Headers

Name	Type	Required	Description
API_KEY	string	Yes	Your API key
Content-Type	string	Yes	`application/json`
APP_ID	string	No	Optional app ID for request tracking

Body

Name	Type	Required	Description
kind	string	Yes	One of `friendly_captcha`, `friendly_captcha_proxy`
url	string	Yes	Page URL where the challenge appears
siteKey	string	Yes	Site key of the challenge
friendlyVersion	string	No	Widget line: `v1` (default), `v2`, `v1-eu`, or `v2-eu`. Must match the site
friendlyCdnOrigin	string	No	Widget script origin for self-hosted or EU sites. Omit for the public CDN
proxy	string	No	For `_proxy` kinds: `host:port` or `host:port:username:password`
platform	string	No	Requested platform label: `windows` (default) or `mac`

Wait for the Result

Get Solve · GET /v2/response/{id}

Use the solve id to fetch the result.

GEThttps://api.captcha.fun/v2/response/{id}

Poll every second until ready is true.

GEThttps://api.captcha.fun/v1/response/{id}

Long polling: the request stays open until the solve finishes or times out. Send it once and wait.

Example

curl -X GET https://api.captcha.fun/v2/response/550e8400-e29b-41d4-a716-446655440000 \
  -H "API_KEY: CAPFUN-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX" \
  -H "Accept: application/json"

import requests

response = requests.get(
    "https://api.captcha.fun/v2/response/550e8400-e29b-41d4-a716-446655440000",
    headers={
        "API_KEY": "CAPFUN-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX",
        "Accept": "application/json"
    }
)

print(response.status_code, response.json())

const response = await fetch(
  "https://api.captcha.fun/v2/response/550e8400-e29b-41d4-a716-446655440000",
  {
    method: "GET",
    headers: {
      "API_KEY": "CAPFUN-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX",
      "Accept": "application/json"
    }
  }
);

const data = await response.json();
console.log(response.status, data);

package main

import (
    "encoding/json"
    "fmt"
    "net/http"
)

func main() {
    req, _ := http.NewRequest("GET", "https://api.captcha.fun/v2/response/550e8400-e29b-41d4-a716-446655440000", nil)
    req.Header.Set("API_KEY", "CAPFUN-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX")
    req.Header.Set("Accept", "application/json")

    client := &http.Client{}
    resp, _ := client.Do(req)
    defer resp.Body.Close()

    var result map[string]interface{}
    json.NewDecoder(resp.Body).Decode(&result)
    fmt.Println(resp.StatusCode, result)
}

import java.net.http.*;
import java.net.URI;

public class Main {
    public static void main(String[] args) throws Exception {
        HttpClient client = HttpClient.newHttpClient();
        HttpRequest request = HttpRequest.newBuilder()
            .uri(URI.create("https://api.captcha.fun/v2/response/550e8400-e29b-41d4-a716-446655440000"))
            .header("API_KEY", "CAPFUN-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX")
            .header("Accept", "application/json")
            .GET()
            .build();

        HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
        System.out.println(response.statusCode() + " " + response.body());
    }
}

using System.Net.Http;

var client = new HttpClient();
client.DefaultRequestHeaders.Add("API_KEY", "CAPFUN-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX");
client.DefaultRequestHeaders.Add("Accept", "application/json");

var response = await client.GetAsync("https://api.captcha.fun/v2/response/550e8400-e29b-41d4-a716-446655440000");
var result = await response.Content.ReadAsStringAsync();

Console.WriteLine($"{(int)response.StatusCode} {result}");

Response

{
  "ready": true,
  "status": "SUCCESS",
  "success": true,
  "userAgent": "RETURNED_USER_AGENT",
  "secUa": "RETURNED_SEC_CH_UA",
  "token": "e8e1a897de2ea1fa5db0d2fd8.ABCdEF.1735689600"
}

{
  "message": "API_KEY Header Missing"
}

Example

curl -X GET https://api.captcha.fun/v1/response/550e8400-e29b-41d4-a716-446655440000 \
  -H "API_KEY: CAPFUN-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX" \
  -H "Accept: application/json"

import requests

response = requests.get(
    "https://api.captcha.fun/v1/response/550e8400-e29b-41d4-a716-446655440000",
    headers={
        "API_KEY": "CAPFUN-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX",
        "Accept": "application/json"
    }
)

print(response.status_code, response.json())

const response = await fetch(
  "https://api.captcha.fun/v1/response/550e8400-e29b-41d4-a716-446655440000",
  {
    method: "GET",
    headers: {
      "API_KEY": "CAPFUN-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX",
      "Accept": "application/json"
    }
  }
);

const data = await response.json();
console.log(response.status, data);

package main

import (
    "encoding/json"
    "fmt"
    "net/http"
)

func main() {
    req, _ := http.NewRequest("GET", "https://api.captcha.fun/v1/response/550e8400-e29b-41d4-a716-446655440000", nil)
    req.Header.Set("API_KEY", "CAPFUN-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX")
    req.Header.Set("Accept", "application/json")

    client := &http.Client{}
    resp, _ := client.Do(req)
    defer resp.Body.Close()

    var result map[string]interface{}
    json.NewDecoder(resp.Body).Decode(&result)
    fmt.Println(resp.StatusCode, result)
}

import java.net.http.*;
import java.net.URI;

public class Main {
    public static void main(String[] args) throws Exception {
        HttpClient client = HttpClient.newHttpClient();
        HttpRequest request = HttpRequest.newBuilder()
            .uri(URI.create("https://api.captcha.fun/v1/response/550e8400-e29b-41d4-a716-446655440000"))
            .header("API_KEY", "CAPFUN-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX")
            .header("Accept", "application/json")
            .GET()
            .build();

        HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
        System.out.println(response.statusCode() + " " + response.body());
    }
}

using System.Net.Http;

var client = new HttpClient();
client.DefaultRequestHeaders.Add("API_KEY", "CAPFUN-XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX");
client.DefaultRequestHeaders.Add("Accept", "application/json");

var response = await client.GetAsync("https://api.captcha.fun/v1/response/550e8400-e29b-41d4-a716-446655440000");
var result = await response.Content.ReadAsStringAsync();

Console.WriteLine($"{(int)response.StatusCode} {result}");

Response

{
  "status": "SUCCESS",
  "success": true,
  "userAgent": "RETURNED_USER_AGENT",
  "secUa": "RETURNED_SEC_CH_UA",
  "token": "e8e1a897de2ea1fa5db0d2fd8.ABCdEF.1735689600"
}

{
  "message": "API_KEY Header Missing"
}

Request and response fields7 response fields

Request

Name	Type	Required	Description
id	string (UUID)	Yes	Path parameter. The `id` from Create Solve
API_KEY	string	Yes	Header. Your API key

Response Fields

Name	Type	Required	Description
ready	boolean	—	`true` when the solve is finished (v2 only)
status	string	—	`PENDING` while solving, then `SUCCESS` or `FAILURE`
success	boolean	—	Whether the solve succeeded
userAgent	string	—	Value to send as `User-Agent` when using the result. Preserve it exactly
secUa	string	—	Value to send as `Sec-CH-UA` when using the result
token	string	—	Solved value: `frc-captcha-solution` (v1) or `frc-captcha-response` (v2)
message	string	—	Failure reason. Omitted on success

Submit the Token

frc-captcha-solution value

Submit the value under the field name the site expects (frc-captcha-solution for v1, frc-captcha-response for v2), then verify it server-side with your Friendly Captcha API key.
Solutions are single-use and expire roughly five minutes after minting — submit them immediately.

When using a successful result, preserve the returned userAgent as User-Agent and secUa as Sec-CH-UA.

Wrong or rejected result? Report the failed solve.