Email Finder API: Discover Work Emails by Name and Domain

An email finder API takes a person's first name, last name, and company domain, then returns their most likely verified work email. The verification step happens at discovery time, so you get an address you can send to, not just a guess you have to check separately. Our free email finder and validator does this in the browser with no account required. The email finder API exposes the same engine over HTTP so you can embed it in any automation workflow, AI agent, or GTM stack.

StartupHub.ai indexes more than 84,000 startups globally, and programmatic email discovery is now one of the most common capabilities built into the GTM automation workflows running on top of that data: every modern outbound stack treats contact discovery as infrastructure, not an optional lookup.

How the Email Finder API Works

The discovery endpoint checks the target domain's email format pattern, constructs candidates from the most common permutations of the person's name, and runs live SMTP verification on each candidate before returning a result. The response includes the confirmed address, a confidence score, the detected domain pattern, and full deliverability status. Your application never has to call a second endpoint to check what was found.

Request: GET /api/v1/email/discover with three parameters: first_name, last_name, and domain. Authenticate with your API key in the Authorization header. Get a free key in under 30 seconds at the API docs page.

Quick Start: Three Ways to Call the Finder API

cURL

curl -s \
  "https://www.startuphub.ai/api/v1/email/discover?first_name=Jane&last_name=Smith&domain=acmecorp.com" \
  -H "Authorization: Bearer YOUR_API_KEY"

Python

import requests

resp = requests.get(
    "https://www.startuphub.ai/api/v1/email/discover",
    params={
        "first_name": "Jane",
        "last_name": "Smith",
        "domain": "acmecorp.com"
    },
    headers={"Authorization": "Bearer YOUR_API_KEY"}
)
data = resp.json()
print(data["email"], data["status"], data["score"])

JavaScript (fetch)

const params = new URLSearchParams({
  first_name: "Jane",
  last_name: "Smith",
  domain: "acmecorp.com"
});

const response = await fetch(
  `https://www.startuphub.ai/api/v1/email/discover?${params}`,
  { headers: { Authorization: "Bearer YOUR_API_KEY" } }
);
const result = await response.json();

if (result.status === "valid") {
  console.log(result.email, result.score); // verified, safe to send
} else if (result.status === "catch_all") {
  // inconclusive: flag for manual review
} else {
  // address could not be confirmed
}

Response Fields Explained

A successful response returns a JSON object with these fields:

• email: the discovered address (e.g. [email protected])
• status: one of valid, catch_all, invalid, or risky
• score: 0-100 confidence number for deliverability
• pattern: the detected domain format (e.g. firstname.lastname)
• mx_found: boolean confirming the domain has a live mail server

Where to Use an Email Finder API

AI agent and automation workflows

AI agents running outbound research need a reliable way to resolve contacts to verified email addresses without human intervention. The discovery endpoint accepts structured inputs and returns structured outputs, with verification already included, making it a natural tool call for agentic pipelines that cannot tolerate manual QA steps between stages.

CRM enrichment at import

When a contact enters your CRM with only a name and company domain, an API call at import time resolves the email before the record is ever saved. This eliminates the manual lookup-and-update cycle and keeps your database clean at the source rather than requiring periodic audits to find empty email fields.

Prospecting scripts and sales tooling

A script looping over a list of target names and domains can discover and validate a prospect list in minutes. The response includes both the email and its deliverability status, so the script can split results into safe-to-send and needs-review buckets without additional processing.

Inbound enrichment

When a new user signs up with a business email domain, the finder API can surface additional contacts at the same company for account-based outreach. Because the API verifies each address it discovers, the results go directly into outbound sequences without a separate verification pass.

Email Finder API vs. Email Verification API

These solve different problems. The verification endpoint (/api/v1/email/validate) takes a complete email address you already have and confirms whether it is deliverable. The finder endpoint (/api/v1/email/discover) takes a name and domain and constructs, then verifies, the address. For most outbound workflows, both appear in sequence: the finder resolves an unknown address, the verifier confirms it. Because the finder already runs verification internally and returns the deliverability status, the second call is optional for single-contact lookups. Use the verifier independently when you have an existing list to clean.

How It Compares to Hunter.io's Finder API

Hunter.io's API combines email finding and verification using a shared credit pool: one credit to find, 0.5 credits to verify. The free tier allows 25 monthly requests across both endpoints combined. Paid plans start at 34 euros per month for 500 credits. The shared credit model means every search depletes the pool regardless of whether the result is used. The StartupHub API separates the free tier by endpoint type: 50 verifications per day and 5 discoveries per day at no cost, with verification included in every discovery response.

Free Tier and Pricing

The free tier includes 5 email discoveries per day with no credit card required. That covers integration testing, ad hoc lookups, and low-volume prospecting. Paid plans at the API docs page scale to thousands of discoveries per month with higher concurrency limits for bulk prospecting scripts. Get your API key in under 30 seconds from the same page.

Frequently Asked Questions

What is an email finder API?

An email finder API is an HTTP endpoint that takes a person's first name, last name, and company domain, then returns their most likely verified work email address. Unlike email verification APIs, which check an address you already have, an email finder API constructs and confirms the address from name and domain inputs alone.

Is there a free email finder API?

Yes. The StartupHub email finder API includes 5 discoveries per day at no cost, no credit card required. Sign up for a free API key at the API docs page. The free tier includes the full response: email, status, score, detected pattern, and MX check.

How accurate is the email finder API?

For domains that respond normally to SMTP probing and use a standard email format, the API confirms the correct address with high confidence. For catch-all domains, it constructs the most likely address based on the detected pattern but marks the status as catch_all to signal that individual mailbox delivery cannot be guaranteed. The score field reflects this uncertainty on a 0-100 scale.

What happens if the API cannot find an email?

If no candidate address can be confirmed, the API returns a status indicating the address could not be resolved, along with any domain-level data it retrieved (MX record presence, catch-all flag). This lets your application handle the failure explicitly rather than receiving a potentially wrong address that would bounce.

Does the finder API include verification?

Yes. The discovery endpoint runs SMTP verification internally before returning a result. You do not need to make a second call to the validation endpoint to check the address it finds. The response includes deliverability status and a confidence score alongside the discovered address.

How do I handle catch-all domains in the finder API?

When the response shows status: "catch_all", the mail server accepts every address at that domain, so definitive confirmation is impossible at the SMTP level. Treat catch-all results as best-guess addresses: usable for small pilot batches where you can monitor bounce rates, but not safe for full-scale campaigns without additional signals that the specific person is genuinely reachable at that address.

What is the rate limit on the email finder API?

The free tier allows 5 discoveries per day. Paid tiers increase this limit for higher-volume workflows. Current rate limits by plan are documented at the API docs page, along with concurrency guidance for bulk prospecting scripts.