Developers

API and AI tools

Check emails from your own app, script or AI tool. The API runs the same checks as the website: format, domain, mail server, temporary inboxes, team addresses and typos.

Address

https://email-chekkr-api.onrender.com

The API is in early access. On the free host it can take about 15 seconds to wake up after a quiet period.

Limits

	Without a key	With an API key
Requests per minute	30 per IP address	120 per key
Emails per batch	50	500
AI tools (MCP)	Not available	Available

Every reply includes RateLimit-Remaining and RateLimit-Reset. Over the limit you get status 429 and a Retry-After header with the seconds to wait.

Check one email

curl "https://email-chekkr-api.onrender.com/v1/verify?email=sample.user@gmial.com"

Reply:

{
  "email": "sample.user@gmial.com",
  "status": "risky",
  "score": 1,
  "reason": "Possible typo — did you mean sample.user@gmail.com?",
  "suggestion": "sample.user@gmail.com",
  "checks": {
    "syntax": true,
    "domain": "gmial.com",
    "mx": "mx",
    "disposable": true,
    "role": false,
    "free": false
  }
}

Check a list

curl -X POST https://email-chekkr-api.onrender.com/v1/verify/batch \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -d '{"emails": ["sample.user@example.com", "hello@mailinator.com"]}'

You get a summary with the count of each result, and results in the same order you sent them.

Check a domain

curl "https://email-chekkr-api.onrender.com/v1/domain?domain=example.com"

Tells you if the domain exists, accepts email, its mail servers, and whether it's a temporary inbox or a free provider like Gmail.

All endpoints

Endpoint	What it does
GET/v1/verify?email=	Check one address
POST/v1/verify	Check one address sent as `{"email": "..."}`
POST/v1/verify/batch	Check a list sent as `{"emails": [...]}`
GET/v1/domain?domain=	Check a domain
POST/mcp	Connection for AI tools (needs a key)
GET/health	Is the API up?

Results are valid, risky, invalid or unknown, with a score from 0 to 100. See what each result means.

Errors

Errors come back as {"error": {"code": "...", "message": "..."}}. Common codes: invalid_input (400), batch_too_large (400), api_key_required or invalid_api_key (401), rate_limited (429).

Use Email Chekkr in AI tools (MCP)

Claude, Cursor and other AI tools can check emails with Email Chekkr. They get three tools: verify_email, verify_emails_batch and check_domain.

To connect over the internet, add this server address in your AI tool and send your API key as a Bearer token:

https://email-chekkr-api.onrender.com/mcp

To run it on your own computer instead, download the code and add this to your AI tool's MCP settings:

{
  "mcpServers": {
    "email-chekkr": {
      "command": "node",
      "args": ["/full/path/to/Email-Chekkr/server/stdio.js"]
    }
  }
}

Privacy

The API doesn't store the addresses you send or write them to its logs. To check a domain it asks public DNS about the domain only.

Get an API key

Keys are free during early access. Ask for one.