Email Verification API

Verify email addresses in milliseconds. REST API, JSON responses, free tier included.

Authentication

All requests require an API key passed in the X-API-Key header. Your key is generated automatically when you sign up — find it in your dashboard under Account Settings.

HTTP Header 
X-API-Key: pj_your_api_key_here
Free tier: 100 verifications/month included with every account. No credit card required. Upgrade anytime for higher volume.

Base URL

All API endpoints are relative to:

Base URL 
https://prospectjet.polsia.app/api/v1

Response Format

All responses are JSON. Successful responses include "success": true. Error responses include "success": false and an "error" code string.

POST /verify

Verify a single email address. Runs four detection layers: syntax, disposable domain, MX record lookup, and role-based detection. Consumes 1 verification credit.

POST /api/v1/verify

Request body:

FieldTypeDescription
email required string The email address to verify
cURL 
curl -X POST https://prospectjet.polsia.app/api/v1/verify \
  -H "Content-Type: application/json" \
  -H "X-API-Key: pj_your_api_key_here" \
  -d '{"email": "john@example.com"}'
JavaScript 
const response = await fetch('https://prospectjet.polsia.app/api/v1/verify', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
    'X-API-Key':     'pj_your_api_key_here'
  },
  body: JSON.stringify({ email: 'john@example.com' })
});

const data = await response.json();
console.log(data.result); // "valid" | "invalid" | "risky" | "unknown"
Python 
import requests

response = requests.post(
    'https://prospectjet.polsia.app/api/v1/verify',
    json={'email': 'john@example.com'},
    headers={'X-API-Key': 'pj_your_api_key_here'}
)

data = response.json()
print(data['result'])  # "valid" | "invalid" | "risky" | "unknown"

Response:

JSON Response 
{
  "success":    true,
  "email":      "john@example.com",
  "result":     "valid",          // "valid" | "invalid" | "risky" | "unknown"
  "confidence": "high",           // "high" | "medium" | "low"
  "reason":     "passed_all_checks",
  "usage": {
    "used":          1,
    "remaining":     99,
    "monthly_limit": 100
  }
}

POST /verify/bulk

Verify up to 100 email addresses in a single request. Consumes N credits (one per email). The entire batch must fit within your remaining quota — if not, a 402 is returned before any processing begins.

POST /api/v1/verify/bulk

Request body:

FieldTypeDescription
emails required string[] Array of email addresses. Max 100 per request.
cURL 
curl -X POST https://prospectjet.polsia.app/api/v1/verify/bulk \
  -H "Content-Type: application/json" \
  -H "X-API-Key: pj_your_api_key_here" \
  -d '{"emails": ["john@example.com", "info@other.com", "test@mailinator.com"]}'
JavaScript 
const response = await fetch('https://prospectjet.polsia.app/api/v1/verify/bulk', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
    'X-API-Key':     'pj_your_api_key_here'
  },
  body: JSON.stringify({
    emails: ['john@example.com', 'info@other.com', 'test@mailinator.com']
  })
});

const data = await response.json();
// data.results is an array of individual verification results
data.results.forEach(r => console.log(r.email, r.result));
Python 
import requests

response = requests.post(
    'https://prospectjet.polsia.app/api/v1/verify/bulk',
    json={'emails': ['john@example.com', 'info@other.com']},
    headers={'X-API-Key': 'pj_your_api_key_here'}
)

data = response.json()
for r in data['results']:
    print(r['email'], r['result'])

Response:

JSON Response 
{
  "success": true,
  "results": [
    { "email": "john@example.com",    "result": "valid",   "confidence": "high",   "reason": "passed_all_checks" },
    { "email": "info@other.com",       "result": "risky",  "confidence": "high",   "reason": "role_based" },
    { "email": "test@mailinator.com",  "result": "invalid", "confidence": "high",   "reason": "disposable_domain" }
  ],
  "usage": {
    "used":          3,
    "remaining":     97,
    "monthly_limit": 100
  }
}

GET /usage

Check your current quota usage. Useful for monitoring and pre-flight checks before bulk operations.

GET /api/v1/usage

cURL 
curl https://prospectjet.polsia.app/api/v1/usage \
  -H "X-API-Key: pj_your_api_key_here"
JSON Response 
{
  "success":   true,
  "api_key":   "pj_your_api_...",
  "tier":      "free",
  "usage": {
    "used":          3,
    "remaining":     97,
    "monthly_limit": 100,
    "reset_date":    "2026-06-01T00:00:00.000Z"
  }
}

Result Values

Every verification returns a result and a confidence level.

ResultMeaningRecommended action
valid string Passed all checks. Safe to send.
invalid string Failed a hard check (bad syntax, disposable domain, no MX). Do not send.
risky string Role-based address (info@, admin@). Email exists but likely low engagement.
unknown string DNS inconclusive. Proceed with caution.

Common reason values: passed_all_checks, invalid_syntax, disposable_domain, no_mx_record, role_based, dns_timeout

Rate Limits

TierMonthly quotaRate limit
Free 100 verifications 100 requests/minute
Starter ($29/mo) 5,000 verifications 1,000 requests/minute
Growth ($79/mo) 25,000 verifications 1,000 requests/minute
Scale ($199/mo) 100,000 verifications 1,000 requests/minute
Quota exhausted? The API returns 402 Payment Required when your monthly quota is used up. Usage resets on the first of each month.

Error Codes

HTTPerror fieldDescription
400 missing_email Request body missing the email field
400 missing_emails Bulk request missing or empty emails array
400 too_many_emails Bulk request contains more than 100 emails
401 invalid_api_key Missing or unrecognized X-API-Key header
402 quota_exceeded Monthly quota exhausted. Upgrade to continue.
402 quota_insufficient Bulk batch requires more credits than remaining quota
429 rate_limited Exceeded per-minute request rate limit
500 internal_error Server error. Safe to retry with exponential backoff.

Full Integration Example

A complete example that verifies a list of emails, filters results, and handles quota errors:

JavaScript (Node.js) 
const API_KEY = 'pj_your_api_key_here';
const BASE    = 'https://prospectjet.polsia.app/api/v1';

async function verifyEmails(emails) {
  // Check quota first
  const usage = await fetch(`${BASE}/usage`, {
    headers: { 'X-API-Key': API_KEY }
  }).then(r => r.json());

  if (usage.usage.remaining < emails.length) {
    throw new Error(`Insufficient quota: ${usage.usage.remaining} remaining`);
  }

  // Verify in batches of 100
  const results = [];
  for (let i = 0; i < emails.length; i += 100) {
    const batch = emails.slice(i, i + 100);
    const res = await fetch(`${BASE}/verify/bulk`, {
      method:  'POST',
      headers: { 'Content-Type': 'application/json', 'X-API-Key': API_KEY },
      body:    JSON.stringify({ emails: batch })
    });
    const data = await res.json();
    results.push(...data.results);
  }

  // Filter to deliverable only
  return results.filter(r => r.result === 'valid');
}

const valid = await verifyEmails([
  'alice@company.com',
  'bob@example.com',
  'noreply@spam.com'
]);
console.log(`${valid.length} deliverable emails`);
Python 
import requests

API_KEY = 'pj_your_api_key_here'
BASE    = 'https://prospectjet.polsia.app/api/v1'
HEADERS = {'X-API-Key': API_KEY}

def verify_emails(emails):
    # Check quota first
    usage = requests.get(f'{BASE}/usage', headers=HEADERS).json()
    if usage['usage']['remaining'] < len(emails):
        raise ValueError(f"Insufficient quota")

    # Verify in batches of 100
    results = []
    for i in range(0, len(emails), 100):
        batch = emails[i:i+100]
        r = requests.post(
            f'{BASE}/verify/bulk',
            json={'emails': batch},
            headers=HEADERS
        ).json()
        results.extend(r['results'])

    # Return deliverable only
    return [r for r in results if r['result'] == 'valid']


valid = verify_emails(['alice@company.com', 'bob@example.com'])
print(f'{len(valid)} deliverable emails')
Ready to start?
Free API key included with every signup. No credit card needed.
Get Your API Key Free →