Comparison

Best email validation APIs in 2026

What the common email validation APIs return, how they handle lists and catch-all domains, and what they cost per email, checked on each vendor’s own pages in October 2026.

Updated November 4, 2026 · 4 min read

Email validation API response and what to compare: checks, price per email, free tier, response fields

The best email validation API depends on your volume and on what your code does with the answer. This page compares four APIs developers use for sign-up forms, CRM imports and list cleaning: emailvalidation.io, ZeroBounce, NeverBounce and Kickbox. It covers price per email, free tiers, what each response contains and how each API handles lists.

Disclosure: we make emailvalidation.io, so we are not neutral. Competitor prices and features are taken from each provider’s own pricing page and API documentation, checked October 29, 2026 (prices again on November 4, 2026); check them before you buy. For a broader comparison of ten tools, including dashboards and list uploads, see the best email verification tools.

Email validation API prices compared

Prices checked November 4, 2026, in US dollars:

APIFreeEntry price5,00010,000100,000
emailvalidation.io100 / month$1.29 for 1,000 (pack); $8.99 / month for 10,000$6.49 (pack)$8.99 / month (10,000)$84.99 / month or pack
ZeroBounce100 / month$39 for 2,000 credits$69$129$649
NeverBounce10 credits at sign-up$8 for 1,000 credits$40$50$400
Kickbox100 at sign-up$5 for 500$40$70$500

Price per email: emailvalidation.io under $0.001 on every plan ($0.0009 on Small, $0.00085 on Large, $0.00028 on Business with 1,000,000 a month) and $0.0013 to $0.00033 with one-off packs, which are valid 12 months; ZeroBounce about $0.02 at the smallest pack, $0.0065 at 100,000; NeverBounce $0.008 up to 5,000, $0.005 from 10,000, $0.004 from 100,000; Kickbox $0.008 at 5,000, $0.005 at 100,000. NeverBounce credits expire 12 months after purchase. ZeroBounce also sells a subscription, ZeroBounce ONE, from $99 a month for 10,000 credits, and NeverBounce a Growth plan from $49 a month for up to 10,000. All emailvalidation.io plans, including yearly billing, are on the pricing page.

What the APIs return

Fieldemailvalidation.ioZeroBounceNeverBounceKickbox
Verdictstatus: valid, invalid, catch_all, risky, do_not_mail, unknown, with sub_status and recommended_action; also state and reasonstatus: valid, invalid, catch-all, unknown, spamtrap, abuse, do_not_mail, with sub-statusesresult: valid, invalid, disposable, catchall, unknown, plus flagsresult: deliverable, undeliverable, risky, unknown, plus a reason
Catch-allstatus: catch_all on every plan; the catch_all field with catch_all=1 (Small plan and up)Own statusOwn resultaccept_all flag
Scorescore 0–1Separate AI scoring (1 credit per email)AI scoring on the Growth planSendex score 0–1
Typo suggestiondid_you_meandid_you_meansuggested_correctiondid_you_mean
ListsPOST /v1/bulk, up to 100,000 per job, signed webhookFile API (send file, file status, get file, delete file)Jobs API with callbacksBatch API, up to 1 million per request, optional callback; list upload
Client librariesJavaScript, Python, PHP, Ruby, Go, C#, R, Rust and Perl SDKs; MCP serverWrappers for 13 languages and platforms, including Python, PHP, Java, Go, C# and mobile SDKsPHP, Ruby, Node.js, Python, Go, .NET, Java; JavaScript widgetNode.js, PHP, Python and Ruby libraries
Unknown resultsNot charged, within a fair-use allowanceNot charged–Refunded

What they check

All four check syntax, DNS/MX and the mailbox over SMTP, and flag disposable and role addresses and catch-all domains. The differences are in the extras:

Request and response examples are on the email validation API page; catch-all email explains what to do with addresses on catch-all domains. How each of these checks works is explained in our guide to email verification.

How to choose the best email validation API

Try the result quality first: validate a sample of your own addresses with the free bulk email verifier, or call the API from your code using our guide to validate email in JavaScript.

Sources

All checked October 29, 2026; the prices of all four again on November 4, 2026:

Frequently asked questions

What is the best email validation API?

For steady volume from your own code, emailvalidation.io costs the least per email of the four ($8.99 for 10,000 a month, $84.99 for 100,000; prices checked November 4, 2026) and returns 21 fields per address, including a status and a recommended action. ZeroBounce is the pick if you want activity data or an EU endpoint, NeverBounce for its client libraries and integrations, Kickbox for a simple pay-as-you-go price list.

What is the cheapest email validation API?

Of the four APIs on this page, emailvalidation.io costs the least: $8.99 for 10,000 validations a month (about $0.0009 per email), or one-off credit packs from $1.29 for 1,000 to $329 for 1,000,000 (valid 12 months). Pay-as-you-go credits at ZeroBounce, NeverBounce and Kickbox cost roughly $0.004–$0.02 per email depending on volume (prices checked November 4, 2026).

Is there a free email validation API?

emailvalidation.io and ZeroBounce both include 100 free validations per month (ZeroBounce with a business-domain sign-up). Kickbox gives 100 free verifications at sign-up, and NeverBounce 10 free credits.

Which email validation API detects catch-all domains?

All four. ZeroBounce returns a catch-all status, NeverBounce a catchall result and Kickbox an accept_all flag. emailvalidation.io returns status: "catch_all" on every plan and fills its catch_all field when you send catch_all=1 on paid plans from Small.

Email validation API

Validate emails in your app

emailvalidation.io checks syntax, MX records and the mailbox over SMTP, flags disposable, role and free addresses and returns a quality score, in one request.

/v1/info Email validation API Read the documentation

100 free validations every month. No credit card required.

GET https://api.emailvalidation.io/v1/info?email=support@emailvalidation.io

{
  "email": "support@emailvalidation.io",
  "user": "support",
  "tag": "",
  "domain": "emailvalidation.io",
  "format_valid": true,
  "mx_found": true,
  "smtp_check": true,
  "catch_all": null,
  "role": true,
  "disposable": false,
  "free": false,
  "score": 0.64,
  "state": "deliverable",
  "reason": "low_quality",
  "did_you_mean": "",
  "catch_all_resolution": null,
  "bounce_probability": null,
  "status": "valid",
  "sub_status": "role_based",
  "explanation": "The mailbox exists, but it is a role address (such as info@ or support@), usually read by a team rather than one person.",
  "recommended_action": "send_with_caution"
}

Keep reading

Best email verification toolsThe best email verification tools of 2026 compared on published facts: price per 10,000 checks, free tiers, API, bulk upload, catch-all handling, integrations. AlternativesFair comparisons of ZeroBounce, NeverBounce, Kickbox, Apollo, Lusha, Hunter and more with emailvalidation.io: vendor prices, free tiers, API and bulk. Email validation APIChecks the syntax, MX records, SMTP mailbox and disposable or free-provider status of any address in real time, as JSON. Validate email addresses in JavaScriptJavaScript email validation, tested: what type=“email” accepts, a stricter regex, validator.js and Zod compared, an MX lookup in Node.js and a mailbox check. Catch-all email addresses explainedWhat a catch-all email domain is, why verifiers can’t confirm its mailboxes, how to detect one, what the API returns and how to send to these addresses safely. Email validation API pricing100 free checks a month, plans from $8.99 for 10,000 checks up to $279 for 1,000,000, and credit packs from $1.29. Monthly or yearly, cancel anytime.

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