Email validation API comparison 2026: botoi vs Hunter.io vs ZeroBounce vs AbstractAPI vs Emailable

Bad email addresses cost more than bounced messages. They inflate your user counts, tank your sender reputation, trigger spam filters, and waste support time on accounts that will never convert. Whether you're validating signups in real time, cleaning a marketing list before a campaign, or filtering leads from a web form, an email validation API is the fastest way to catch problems before they compound.

This guide compares five email validation APIs available in 2026: botoi, Hunter.io, ZeroBounce, AbstractAPI, and Emailable. Each section covers what the API does, what it costs, and how to call it. The comparison tables at the end give you a side-by-side view to make your decision faster.

When you need email validation

Three common scenarios drive teams to add email validation:

• Signup forms. Catch typos, disposable addresses, and invalid domains before creating an account. This protects your database from junk and reduces fake trial abuse.
• Lead generation. Sales teams that buy or scrape email lists need to verify addresses before sending outreach. Sending to dead addresses hurts your domain reputation with email providers like Gmail and Outlook.
• List cleaning. Email lists degrade over time. People change jobs, domains expire, and inboxes fill up. Running a batch validation pass before each campaign keeps your bounce rate under control.

The API you choose depends on which of these scenarios matters most, how many emails you process, and how much you're willing to pay per check.

Feature comparison

Pricing comparison

A few things to note. botoi's pricing includes access to all 150+ API endpoints, not only email validation. If you also need DNS lookups, URL metadata, hashing, or image generation, the \$9/mo covers everything. Hunter.io's plan includes email finder and domain search features beyond verification. ZeroBounce and Emailable charge per email, which works well for batch list cleaning but can get expensive for real-time validation at scale.

Code examples

botoi

botoi splits email validation into three focused endpoints. You can call them individually depending on what you need.

Disposable email check:

curl -X POST https://api.botoi.com/v1/disposable-email/check \
  -H "Content-Type: application/json" \
  -d '{"email": "test@mailinator.com"}'

Response:

{
  "success": true,
  "data": {
    "email": "test@mailinator.com",
    "domain": "mailinator.com",
    "is_disposable": true,
    "is_free": false,
    "provider": "Mailinator"
  }
}

MX record verification:

curl -X POST https://api.botoi.com/v1/email-mx/verify \
  -H "Content-Type: application/json" \
  -d '{"email": "hello@acme.com"}'

Syntax validation:

curl -X POST https://api.botoi.com/v1/email/validate \
  -H "Content-Type: application/json" \
  -d '{"email": "hello@acme.com"}'

No API key is required for the free tier. Add an Authorization: Bearer YOUR_KEY header when you need higher rate limits.

Hunter.io

Hunter.io bundles all checks into a single GET endpoint. An API key is required for every request, including free tier usage.

curl "https://api.hunter.io/v2/email-verifier?email=test@mailinator.com&api_key=YOUR_API_KEY"

Response:

{
  "data": {
    "status": "invalid",
    "result": "undeliverable",
    "score": 0,
    "email": "test@mailinator.com",
    "regexp": true,
    "gibberish": false,
    "disposable": true,
    "webmail": false,
    "mx_records": true,
    "smtp_server": true,
    "smtp_check": false
  }
}

The response includes a confidence score from 0 to 100 and separate boolean fields for each validation type. The smtp_check field indicates whether the mailbox was confirmed reachable at the SMTP level.

ZeroBounce

ZeroBounce returns a status and sub_status that categorize the email into buckets like "valid", "invalid", "catch-all", and "do_not_mail".

curl "https://api.zerobounce.net/v2/validate?api_key=YOUR_API_KEY&email=test@mailinator.com"

Response:

{
  "address": "test@mailinator.com",
  "status": "do_not_mail",
  "sub_status": "disposable",
  "domain_age_days": "5095",
  "free_email": false,
  "mx_found": true,
  "smtp_provider": "mailinator"
}

The domain_age_days field helps identify recently created domains that are often associated with spam or fraud.

AbstractAPI

AbstractAPI uses a GET request with the email as a query parameter. Each check field is wrapped in an object with a value key.

curl "https://emailvalidation.abstractapi.com/v1/?api_key=YOUR_API_KEY&email=test@mailinator.com"

Response:

{
  "email": "test@mailinator.com",
  "is_valid_format": { "value": true },
  "is_disposable_email": { "value": true },
  "is_free_email": { "value": false },
  "is_mx_found": { "value": true },
  "is_smtp_valid": { "value": false },
  "quality_score": "0.10"
}

The quality_score ranges from 0.00 to 1.00. A score below 0.50 typically indicates the address is risky or undeliverable.

Emailable

Emailable provides a state field ("deliverable", "undeliverable", "risky", "unknown") alongside a numeric score.

curl "https://api.emailable.com/v1/verify?email=test@mailinator.com&api_key=YOUR_API_KEY"

Response:

{
  "state": "undeliverable",
  "reason": "rejected_email",
  "risk": "high",
  "disposable": true,
  "free": false,
  "mx_record": "mail.mailinator.com",
  "score": 0
}

Emailable is the only provider in this list without a free tier. You need a paid plan to make any API calls.

Which one to pick

The right choice depends on your use case, budget, and scale. Here's a decision matrix to narrow it down:

• You want the cheapest way to start. botoi's free tier requires no API key and no signup. Send a POST request and get a result. At \$9/mo, the paid plan is the lowest-cost option and includes access to 150+ other developer API endpoints. The tradeoff: no SMTP-level mailbox verification.
• You need deep SMTP verification for cold outreach. Hunter.io is built for sales teams. It verifies mailbox deliverability at the SMTP level and integrates with its email finder and campaign tools. The \$49/mo starting price is steep, but it covers the full lead generation workflow.
• You're cleaning a large email list before a campaign. ZeroBounce and Emailable are designed for batch processing. Both accept CSV uploads and return results with risk classifications. ZeroBounce's free 100 credits help you test before committing. Emailable requires a paid plan from day one.
• You want a simple validation check with minimal setup. AbstractAPI's single GET endpoint and \$12/mo entry price make it a straightforward option. The response structure is verbose but covers the main checks. The free tier's 100 requests per month is enough for testing and prototyping.
• You need validation as part of a broader API toolkit. botoi is the only provider on this list that bundles email validation with DNS lookups, URL metadata extraction, QR code generation, hashing, JWT decoding, and 140+ other endpoints under a single subscription. If your project needs multiple API capabilities, this consolidation saves both money and integration complexity.

Key tradeoffs to consider

Accuracy vs. speed. SMTP-level verification (Hunter.io, ZeroBounce, Emailable) gives you higher confidence that a mailbox exists, but these checks take 1-5 seconds per email. Syntax, MX, and disposable checks (botoi, AbstractAPI) return in under 100ms. For real-time signup validation, speed often matters more than perfect accuracy.

Per-email vs. flat-rate pricing. Credit-based pricing (ZeroBounce, Emailable) works well when you validate in batches. You know exactly how many emails you'll check and can buy credits accordingly. Flat-rate subscriptions (botoi, Hunter.io, AbstractAPI) work better for real-time validation where volume is unpredictable.

Single endpoint vs. composable endpoints. Most providers bundle everything into one API call. botoi splits the checks into separate endpoints, which means you can call only what you need. If you only care about disposable detection, you make one call instead of paying for SMTP checks you don't use. The tradeoff is more integration work if you want the full picture.