Email validation · Best email verification APIs
Email verification API comparison
Best email verification APIs in 2026, compared for signup checks.
Every figure comes from each vendor's own pricing and docs pages, read 2026-11-04. "Not listed" means we did not find it on those pages, not that it does not exist. Last reviewed: 2026-11-04.
50,000 validations
$49.99/mo
$0.001 per extra validation. 100 validations a month free, no credit card.
No credit card required.
Short answer by use case.
Real-time checks at signup: Trueguard.
One large list, cleaned once: MillionVerifier or DeBounce.
Native ESP or CRM integrations: NeverBounce or ZeroBounce.
A SOC 2 report for your vendor checklist: Emailable or Clearout.
An official SDK: Kickbox, Emailable or Verifalia.
Eleven email verification APIs at 50,000 checks.
Ranked by criteria met, then by price at 50,000 checks.
| Rank | Criteria met | Price at 50,000 | Per check | Billing | Free tier |
|---|---|---|---|---|---|
| 1. Trueguard | 5 of 6 | $49.99 / month | $0.001 | Monthly plan | 100 a month, no card |
| 2. Abstract API | 5 of 6 | $199 / monthStarter costs $99 and Standard $179 at 50,000. The disposable and catch-all flags appear only in the Professional sample. | $0.00398 | Monthly plan, Professional | 100 requests, no card |
| 3. Bouncer | 4 of 6 | $200 / month | $0.004 | Monthly plan (pack $250) | 100 credits one-time, no card |
| 4. Clearout | 4 of 6 | $292 / month | $0.00584 | Monthly plan (one-time $325) | 100 credits, lifetime, no card. The free API is limited to 3 requests a minute. |
| 5. Emailable | 3 of 6 | $208.25 / month | $0.00417 | Monthly plan (pack $245) | 250 credits one-time |
| 6. Kickbox | 3 of 6 | $275Credits work for lists and the real-time API. Kickbox's API page lists $400 for 50,000 (read 2026-11-04). | $0.0055 | Credit pack, expires after 1 year | 100 verifications, no card |
| 7. ZeroBounce | 3 of 6 | $379 / month | $0.00758 | Monthly plan | 100 credits a month |
| 8. DeBounce | 1 of 6 | $69 | $0.00138 | Credits never expire. $75 pay as you go, $69 on the Monthly toggle. | 100 credits one-time, no card |
| 9. MillionVerifier | 1 of 6 | $89 | $0.00178 | Credit pack, never expires | 100 credits, no card |
| 10. Verifalia | 1 of 6 | $219Shown as EUR 199 to an EU browser on 2026-11-04. | $0.00438 | Credit pack, never expires | 25 credits a day |
| 11. NeverBounce | 1 of 6 | $250 | $0.005 | Credit pack, expires after 12 months | 10 free credits. API use past them needs a card. |
Prices are each vendor's published rate for 50,000 checks, read 2026-11-04. See the full price breakdown at 50,000 checks.
How we ranked these APIs.
We checked six things that matter when you call an API at signup. Each provider gets one point per criterion its own docs confirm. Ties go to the lower price for 50,000 checks. Trueguard publishes this page and wrote these criteria, so the full matrix is below for you to check. Trueguard fails one of them, because it bills every result, invalid and unknown included. We read every vendor page on 2026-11-04. We did not test accuracy or speed.
A criterion we could not confirm counts as not met. If we got one wrong, tell us and we will re-check it.
- Disposable, catch-all, role and free-mail flags in one response. A signup form needs these signals from a single call, without a second request per address.
- API key sent in a request header, not the URL. Keys in a URL end up in server logs, browser history and referrer headers.
- Free tier with no card. You can test the real endpoint with your own addresses before you give a vendor payment details.
- Monthly plan that covers 50,000 checks and refills each month. Signup traffic is continuous, so a pack that runs out means buying again.
- Unknown results are not billed. Some mail servers never answer a probe, and you should not pay for a result that tells you nothing.
- Domain age in the response. A domain registered last week is a strong signup risk signal.
| Provider | Disposable, catch-all, role and free-mail flags in one response | API key sent in a request header, not the URL | Free tier with no card | Monthly plan that covers 50,000 checks and refills each month | Unknown results are not billed | Domain age in the response |
|---|---|---|---|---|---|---|
| Trueguard | Yes | Yes | Yes | Yes | NoBills every result, invalid and unknown included. | Yes |
| Abstract API | YesShown in the Professional plan sample response. | Yes | Yes | Yes | NoEvery request is billed. | YesStandard plan and up. |
| Bouncer | Yes | Yes | Yes | Yes | Not listed | Not listed |
| Clearout | NoCatch-all comes as a status value, not a separate flag. | Yes | Yes | Yes | Yes | Not listed |
| Emailable | Yes | Yes | Not listed | Yes | Not listed | Not listed |
| Kickbox | Yes | No | Yes | No | Yes | Not listed |
| ZeroBounce | NoDisposable and role come as sub_status values. | NoThe api_key goes in the query string. | Not listed | Yes | Yes | Yes |
| DeBounce | NoRole and free-mail are fields. Disposable and accept-all come as codes. | No | Yes | Not listedThe $69 option sits beside the words "No Monthly Payments". | Not listed | Not listed |
| MillionVerifier | NoDisposable and catch-all come as result values. | No | Yes | No | Not listed | Not listed |
| Verifalia | Not listed | Yes | Not listed | No | Not listed | Not listed |
| NeverBounce | Yes | No | No | No | Not listed | Not listed |
Bulk, integrations, SDKs and compliance
| Provider | Bulk | Integrations | SDKs | Compliance |
|---|---|---|---|---|
| Trueguard | No. One email per request. | None | REST only | No SOC 2, no SLA |
| Abstract API | CSV up to 50,000 rows | Not listed | REST only | SOC 2 Type II, uptime SLA (vs page) |
| Bouncer | Batch up to 500,000 | Named list | Not listed | GDPR, EU-hosted |
| Clearout | CSV and Excel upload | Named list | Not listed | ISO 27001 and SOC 2 Type II claimed |
| Emailable | Batch | Through Zapier and Make | Ruby, Node, Python, CLI | SOC 2 Type II claimed |
| Kickbox | Batch up to 1,000,000 | Named list | Python, PHP, Ruby, Node | "SOC II certified" claimed |
| ZeroBounce | Yes | 60+ | 14 languages documented | SOC 2, ISO 27001 (vs page, read 2026-08-16) |
| DeBounce | CSV and TXT | Named list | Not listed | GDPR |
| MillionVerifier | CSV | 40+ | Not listed | GDPR. "SOC 2 Controls" label only |
| Verifalia | Yes | Not listed | .NET, Go, Java, PHP, Ruby, JS | Not listed |
| NeverBounce | Yes | 80+ | cURL, Node, PHP, Python, Ruby, Go, Java, .NET listed | Not listed |
The APIs in rank order.
Trueguard
Best for
Real-time signup checks on a monthly plan, from a vendor that also runs bot and fraud prevention.
Price at 50,000
$49.99 / month, $0.001 a check.
Where it falls short
Bills invalid and unknown results. No bulk upload, SDKs, integrations, SOC 2, SLA or typo suggestions.
Abstract API
Best for
Breach data and enrichment in the same response, with SOC 2 Type II and an uptime SLA.
Price at 50,000
$199 / month, $0.00398 a check. Starter costs $99 and Standard $179 at 50,000. The disposable and catch-all flags appear only in the Professional sample.
Where it falls short
Every request is billed, unknown included. The disposable and catch-all flags appear only in the Professional sample.
Bouncer
Best for
A risk score and toxicity flag in the response, with data hosted in the EU.
Price at 50,000
$200 / month, $0.004 a check.
Where it falls short
Its docs do not list domain age or how unknown results on API calls are billed.
Clearout
Best for
Verification, email finding and form protection from one vendor with ISO 27001 and SOC 2 Type II claims.
Price at 50,000
$292 / month, $0.00584 a check.
Where it falls short
The free plan API is limited to 3 requests a minute.
Emailable
Best for
Official libraries in Ruby, Node and Python, a SOC 2 Type II claim, and refunds on unknown list results.
Price at 50,000
$208.25 / month, $0.00417 a check.
Where it falls short
The free-tier card requirement is not listed.
Kickbox
Best for
A free sandbox, a Sendex quality score and SDKs in four languages.
Price at 50,000
$275, $0.0055 a check. Credits work for lists and the real-time API. Kickbox's API page lists $400 for 50,000 (read 2026-11-04).
Where it falls short
Credits expire after a year.
ZeroBounce
Best for
Spam-trap and abuse statuses, with 60+ integrations.
Price at 50,000
$379 / month, $0.00758 a check.
Where it falls short
The highest monthly price here at 50,000. The API key goes in the URL.
DeBounce
Best for
Pay-as-you-go credits that never expire.
Price at 50,000
$69, $0.00138 a check.
Where it falls short
The API key goes in the URL. A catch-all validation costs 10 credits.
MillionVerifier
Best for
Low-cost bulk list cleaning, with no charge for catch-all or unknown results.
Price at 50,000
$89, $0.00178 a check.
Where it falls short
No monthly plan. The API key goes in the URL.
Verifalia
Best for
Occasional checks, with 25 free credits a day and credits that never expire.
Price at 50,000
$219, $0.00438 a check. Shown as EUR 199 to an EU browser on 2026-11-04.
Where it falls short
Credit packs only. Priced in EUR in our read.
NeverBounce
Best for
Cleaning lists inside 80+ integrations, with a conditional bounce guarantee.
Price at 50,000
$250, $0.005 a check.
Where it falls short
50,000 comes only as an expiring pack. 10 free credits.
One call, one response.
Trueguard request
curl -X POST https://api.trueguard.io/v2/email/validation \
-H "X-API-KEY: $YOUR_KEY" \
-H "Content-Type: application/json" \
-d '{"email":"founder@yourcompany.com"}'Response
{
"email": "name@gmail.com",
"rawEmail": "name@gmail.com",
"syntax": { "isValid": true },
"deliverability": {
"status": "safe",
"isSmtpValid": true,
"isMxValid": true,
"isCatchall": false,
"isInboxFull": false,
"isDeliverable": true,
"isDisabled": false,
"mxRecords": [
"gmail-smtp-in.l.google.com",
"alt1.gmail-smtp-in.l.google.com",
"alt2.gmail-smtp-in.l.google.com",
"alt3.gmail-smtp-in.l.google.com",
"alt4.gmail-smtp-in.l.google.com"
]
},
"domain": {
"name": "gmail.com",
"age": 11363,
"isLive": true,
"isRisky": false
},
"quality": {
"isDisposable": false,
"isFree": true,
"isRole": false,
"isSubaddress": false
}
}The response carries isCatchall, isDisposable, isRole, isFree and domain age. See the email verification API, the API reference, or check one address free.
How each API bills unknown results.
An unknown result means the mail server gave no answer either way.
Clearout, ZeroBounce and Kickbox say they do not bill unknown results. Trueguard bills every result, invalid and unknown included. Where a cell says "Not listed", we did not find a statement on the pages we read.
| Provider | Unknown results | Billing model |
|---|---|---|
| Trueguard | BilledBills every result, invalid and unknown included. | Monthly plan |
| Abstract API | BilledEvery request is billed. | Monthly plan, Professional |
| Bouncer | Not listed | Monthly plan (pack $250) |
| Clearout | Not billed | Monthly plan (one-time $325) |
| Emailable | Not listed | Monthly plan (pack $245) |
| Kickbox | Not billed | Credit pack, expires after 1 year |
| ZeroBounce | Not billed | Monthly plan |
| DeBounce | Not listed | Credits never expire. $75 pay as you go, $69 on the Monthly toggle. |
| MillionVerifier | Not listed | Credit pack, never expires |
| Verifalia | Not listed | Credit pack, never expires |
| NeverBounce | Not listed | Credit pack, expires after 12 months |
Real-time or bulk?
Trueguard handles one address per request and has no file upload. That fits a signup form, where you check an address the moment a user types it. If you have a list to clean once, a bulk provider from the table above fits better. Each provider's free tier is compared on our free email verification API page.
Which one should you pick?
Choose Trueguard
You run signup checks.
You need 50,000 checks a month on a monthly plan.
You want domain age and risky TLD in the verdict.
You want fraud signals on the same platform.
Pick another provider if
One large list to clean once: MillionVerifier or DeBounce.
Native ESP or CRM integrations: NeverBounce (80+) or ZeroBounce (60+).
A SOC 2 report on your vendor checklist: Emailable or Clearout. Abstract API also lists an uptime SLA.
An official SDK: Kickbox, Emailable or Verifalia.
Unknown results not billed on API calls: Kickbox, ZeroBounce or Clearout.
Breach data or enrichment: Abstract API. Email finding: Clearout.
The three Trueguard plans.
No credit multipliers, and overage at the same rate as the plan.
Standard
Popular$49.99 / month
50,000 validations / month
Overage: $0.001 per validation
Get your API keyFrequently asked questions
Something out of date? Tell us and we will correct it.
What is the best email verification API?
It depends on the job. For real-time signup checks, Trueguard meets 5 of our 6 criteria and ties Abstract API, then wins on price: $49.99 against $199 a month at 50,000. For bulk list cleaning or native integrations, other providers on this page fit better.
What is the difference between email validation and email verification?
Most vendors use the two words for the same thing. Syntax and MX checks confirm the domain can receive mail. An SMTP check asks the mail server if the mailbox exists. Trueguard returns both in one response.
Is there a free email verification API?
Yes. Trueguard gives 100 validations a month with no card. Emailable gives 250 credits once, Verifalia 25 a day, and NeverBounce 10 credits. Most others give 100 credits once (as of 2026-11-04).
How much does an email verification API cost for 50,000 checks?
At 50,000 checks, monthly plans on this page run from $49.99 (Trueguard) to $379 (ZeroBounce). Credit packs for 50,000 run from $69 (DeBounce) to $275 (Kickbox). The full price breakdown is on our price comparison page.
Do email verification APIs charge for unknown or invalid results?
Trueguard bills every result, invalid and unknown included. Clearout, ZeroBounce and Kickbox say unknown results are free (as of 2026-11-04).
Should I block catch-all addresses at signup?
Trueguard returns catch-all addresses as risky. When Google or Microsoft confirms the mailbox, it returns safe with isCatchall true. Flag risky signups for review instead of blocking them.
Should I use real-time or bulk verification?
Real-time checks one address when a user enters it. Bulk cleans a list you already have. Trueguard does real-time only, one address per request.
Why does Trueguard rank itself first?
We publish this page and we chose the criteria. Trueguard ties Abstract API at 5 of 6 and comes first on price at 50,000. The full matrix is on the page, so you can re-rank it yourself.
