Your first check in five minutes.

Get an API key

Sign in and create a key in your API keys settings. The key is shown once and cannot be recovered, so copy it straight away. There are two key types: a sandbox key (prefix es_test_) returns deterministic fixtures and spends nothing, so you can build against it first; a live key (prefix es_live_) verifies real addresses. The free tier gives you 100 live verifies a month. See sandbox testing for the test addresses.

Export it as an environment variable so it never touches your code. Every example below reads ES_KEY from the environment and sends it in the X-API-Key header.

export ES_KEY="4f8c92a17b3d…"

Install the SDK

Pick your language. Each SDK is a thin wrapper over one HTTPS endpoint, all open source. If you would rather not add a dependency, curl works everywhere and needs nothing.

# node 18+ · ESM or CommonJS
npm install @emailsherlock/node

# python 3.9+
pip install emailsherlock-sdk

# go 1.21+
go get github.com/Emailsherlock1/go

# php 8.1+
composer require emailsherlock/client

# no SDK needed, curl is enough
curl --version

Run your first check

One address in, one result out, typically in under a second. The call on the right is complete and copy-paste ready. Swap the address for one of your own.

The body is a single field, email. The response is one result object with the verdict and every signal behind it. The same shape comes back from the batch endpoint, one per address.

curl https://api.emailsherlock.com/v1/credits \
  -H "X-API-Key: $ES_KEY" \
  -H "Content-Type: application/json" \
  -d '[]'

import { Emailsherlock } from '@emailsherlock/node';

const es = new Emailsherlock(process.env.ES_KEY);

const result = await es.credits({  });

from emailsherlock import Emailsherlock

es = Emailsherlock(api_key=os.environ["ES_KEY"])

result = es.credits()

import emailsherlock "github.com/Emailsherlock1/go"

es := emailsherlock.New(os.Getenv("ES_KEY"))

result, err := es.Credits(ctx, )

<?php
use Emailsherlock\Client;

$es = new Client(getenv('ES_KEY'));

$result = $es->credits([]);

{
    "plan": "Free",
    "sandbox": false
}

Read the result

The result field is the verdict. The booleans and the score are the signals behind it, so you can branch on whichever matters to your flow.

Move to production

Your first call already hit the live API, so there is no key or endpoint to swap. Four things separate a demo from a production integration.