Shape API Reference

Get Shape Security headers for one protected request.

The Captcha.fun Shape API accepts kind, url, challengeHtml, protectedUrl and returns Shape request headers. 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
challengeHtml — Captured HTML of the page that loads Shape’s sensor
protectedUrl — Endpoint the headers are for. Replay them on a request to exactly this URL
A proxy, if the result must come from your own IP (shape_proxy)

Use kind

Good to Know

The Shape product replays the page that loads Shape's sensor (ssx.mod.js or an inline equivalent), lets the sensor arm, then fires a request against your protected endpoint from the browser and harvests the Shape headers off the wire.

Shape headers are URL-bound — they encode the request URL into their telemetry — so one solve produces one replayable header set for exactly the endpoint you pass in protectedUrl. Mint a fresh header set per protected endpoint.

A few gateways reject synthetic captures at the app layer; the solver detects those protected URLs and drives the site's real sign-in UI to mint the set instead.

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": "shape",
  "url": "https://your-domain.example/login",
  "challengeHtml": "<CAPTURED_LOGIN_PAGE_HTML>",
  "protectedUrl": "https://your-domain.example/api/login"
}'

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": "shape", "url": "https://your-domain.example/login", "challengeHtml": "<CAPTURED_LOGIN_PAGE_HTML>", "protectedUrl": "https://your-domain.example/api/login"},
)

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": "shape",
  "url": "https://your-domain.example/login",
  "challengeHtml": "<CAPTURED_LOGIN_PAGE_HTML>",
  "protectedUrl": "https://your-domain.example/api/login"
})
});

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 fields6 body fields · 4 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 `shape`, `shape_proxy`
url	string	Yes	Page URL where the challenge appears
challengeHtml	string	Yes	Captured HTML of the page that loads Shape’s sensor
protectedUrl	string	Yes	Endpoint the headers are for. Replay them on a request to exactly this URL
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": "",
  "headers": {
    "x-6a7b8c-a": "0:0:0:0:1:2:3:...",
    "x-6a7b8c-b": "1:1:1:...",
    "x-6a7b8c-f": "abc123..."
  }
}

{
  "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": "",
  "headers": {
    "x-6a7b8c-a": "0:0:0:0:1:2:3:...",
    "x-6a7b8c-b": "1:1:1:...",
    "x-6a7b8c-f": "abc123..."
  }
}

{
  "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
headers	object	—	Shape headers to replay as-is: the `x-<customer-id>-a` / `a0` / `b` / `c` / `d` / `f` / `z` family plus extras like `x-application-mouse-tool-key`
message	string	—	Failure reason. Omitted on success

Replay the Request

Shape request headers

Send one outbound request to exactly protectedUrl with every returned header set verbatim, and the returned userAgent as your User-Agent header.
Replay the set from the same egress IP as the solve, with the returned userAgent as your User-Agent header — the headers are bound to the solving browser's identity.

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.