Solve Image CAPTCHA with Node.js and CaptchaAI

Image CAPTCHAs display distorted text that users must type. They appear on government sites, legacy forms, and registration pages. CaptchaAI reads the image and returns the text. This guide shows how to do it from Node.js.

Prerequisites

Item	Value
CaptchaAI API key	From captchaai.com
Node.js	14+
Libraries	`axios`, `fs`
Image format	JPG, PNG, or GIF (100 bytes – 100 KB)

Method A: Base64 submission

const axios = require('axios');
const fs = require('fs');

const API_KEY = 'YOUR_API_KEY';
const sleep = (ms) => new Promise((r) => setTimeout(r, ms));

// Read and encode the image
const imageB64 = fs.readFileSync('captcha.png').toString('base64');

// Submit to CaptchaAI
const { data: submitData } = await axios.post('https://ocr.captchaai.com/in.php', null, {
  params: {
    key: API_KEY,
    method: 'base64',
    body: imageB64,
    json: 1,
  },
});

if (submitData.status !== 1) throw new Error(submitData.request);
const taskId = submitData.request;
console.log(`Task submitted: ${taskId}`);

Method B: File upload

const FormData = require('form-data');

const form = new FormData();
form.append('key', API_KEY);
form.append('method', 'post');
form.append('json', '1');
form.append('file', fs.createReadStream('captcha.png'));

const { data: submitData } = await axios.post('https://ocr.captchaai.com/in.php', form, {
  headers: form.getHeaders(),
});

const taskId = submitData.request;

Poll for the text result

await sleep(5000);

let captchaText;
for (let i = 0; i < 30; i++) {
  const { data: pollData } = await axios.get('https://ocr.captchaai.com/res.php', {
    params: { key: API_KEY, action: 'get', id: taskId, json: 1 },
  });

  if (pollData.status === 1) {
    captchaText = pollData.request;
    console.log(`CAPTCHA text: ${captchaText}`);
    break;
  }
  if (pollData.request !== 'CAPCHA_NOT_READY') {
    throw new Error(pollData.request);
  }
  await sleep(5000);
}

Accuracy parameters

// Digits only, 4-6 characters
const { data } = await axios.post('https://ocr.captchaai.com/in.php', null, {
  params: {
    key: API_KEY,
    method: 'base64',
    body: imageB64,
    numeric: 1,      // digits only
    min_len: 4,       // minimum length
    max_len: 6,       // maximum length
    json: 1,
  },
});

Parameter	Value	Purpose
`numeric`	`1` = digits, `2` = letters	Limits characters
`min_len` / `max_len`	Integer	Length constraints
`calc`	`1`	Computes math expression
`regsense`	`1`	Case-sensitive

Complete working example

const axios = require('axios');
const puppeteer = require('puppeteer');
const fs = require('fs');

const API_KEY = 'YOUR_API_KEY';
const sleep = (ms) => new Promise((r) => setTimeout(r, ms));

async function solveImageCaptcha() {
  // 1. Load page and screenshot CAPTCHA
  const browser = await puppeteer.launch();
  const page = await browser.newPage();
  await page.goto('https://example.com/register');

  const captchaEl = await page.$('#captcha-image');
  await captchaEl.screenshot({ path: 'captcha.png' });

  // 2. Encode and submit
  const imageB64 = fs.readFileSync('captcha.png').toString('base64');
  const { data: submit } = await axios.post('https://ocr.captchaai.com/in.php', null, {
    params: { key: API_KEY, method: 'base64', body: imageB64, json: 1 },
  });
  const taskId = submit.request;

  // 3. Poll for text
  await sleep(5000);
  let text;
  for (let i = 0; i < 30; i++) {
    const { data: poll } = await axios.get('https://ocr.captchaai.com/res.php', {
      params: { key: API_KEY, action: 'get', id: taskId, json: 1 },
    });
    if (poll.status === 1) { text = poll.request; break; }
    if (poll.request !== 'CAPCHA_NOT_READY') throw new Error(poll.request);
    await sleep(5000);
  }

  // 4. Type and submit
  await page.type('#captcha-input', text);
  await page.click('form [type="submit"]');
  console.log(`Solved: ${text}`);
  await browser.close();
}

solveImageCaptcha().catch(console.error);

Expected output:

Solved: ABC123

Common errors

Error	Cause	Fix
`ERROR_WRONG_FILE_EXTENSION`	Unsupported format	Use JPG, PNG, or GIF
`ERROR_TOO_BIG_CAPTCHA_FILESIZE`	Image > 100 KB	Compress first
`ERROR_ZERO_CAPTCHA_FILESIZE`	Image < 100 bytes	Verify the image
`CAPCHA_NOT_READY`	Still solving	Poll every 5 seconds