Buyer guide · SimpleVerifier Team
The best email validation API for developers: what to compare
The best email validation API is the one that does a live SMTP mailbox check, tells you plainly when it could not confirm an address, and costs least at your monthly call volume. SimpleVerifier's API returns valid, risky or invalid with a reason and a send decision, at 120 calls a minute per key; Pro is $39 a month with 10,000 calls a month included, then $1.50 per 1,000. The table prices other APIs at 10k, 100k and 1M calls.
Five things separate validation APIs, and all five can be checked before you sign up: whether the mailbox is actually probed or only syntax and MX are checked, what comes back for catch-all and unconfirmable addresses, the rate limit per key, what happens when you pass the quota, and the price at your volume.
Test the first one yourself: send an invented address at a real company domain. An API that probes the mailbox returns invalid or risky; a syntax-and-MX check returns valid.
Monthly cost of API volume, by vendor
| Vendor | 10,000 a month | 100,000 a month | 1,000,000 a month |
|---|---|---|---|
| SimpleVerifier | $39 | $99 | $949 |
| Reoon | $11.90 | $116.40 | $972 |
| Bouncify | $19 | $99 | $479 |
| DeBounce | $23 | $124.20 | $750 |
| EmailListVerify | $25 | $168 | $1,860 |
| Mailfloss | $29 | $209 | $1,200 |
| Pabbly Email Verification | $29 | Not published | Not published |
| EmailValidation.io | $34.99 | $94.99 | Not published |
| MillionVerifier | $39 | $149 | $449 |
| Abstract API | $39 | $199 | Not published |
| Bouncer | $48 | $320 | $1,600 |
| NeverBounce | $49 | $159 | $999 |
| Email List Validation | $49 | $229 | $899 |
| Emailable | $51 | $357 | $1,785 |
| Clearout | $58 | $360 | $1,260 |
| MailboxValidator | $59.95 | $199.95 | $699.95 |
| QuickEmailVerification | $60 | $320 | $1,350 |
| Kickbox | $70 | $500 | $2,999 |
| Xverify | $70 | $400 | $1,500 |
| Mailboxlayer | $74.99 | $249.99 | Not published |
| MailerCheck | $80 | $500 | $2,000 |
| Email Hippo | $88.40 | $468 | $1,871.90 |
| ZeroBounce | $99 | $449 | $2,499 |
| Enrichley | $149 | $1,699 | Not published |
Lowest published route for that many checks a month, read from each vendor's pricing page. Ours is the cheapest of our plans for that many API calls on monthly billing, including its per-1,000 price. Validation-API vendors and verifiers with an API are both listed. Vendor prices read 12 Oct 2026 to 30 Oct 2026. Each vendor links to its comparison page, which records the date its prices were read. Check their site for current pricing before you buy.
SimpleVerifier facts: prices, packs and limits
| What it is | Email verification with a real SMTP mailbox check: each address comes back valid, risky or invalid with a reason. Includes an email finder on Pro and up. |
|---|---|
| Price per check | Starter $9/mo for 2,500 ($3.60 per 1,000); Growth $19/mo for 10,000 ($1.90 per 1,000); Pro $39/mo, 100,000 a month at full speed ($0.39 per 1,000 when used), then slower, never cut off. Business $99/mo with 300,000 at full speed; Agency $249/mo with 750,000 at full speed. |
| One-time packs | 10,000 for $15 ($1.50 per 1,000); 25,000 for $29 ($1.16 per 1,000); 50,000 for $49 ($0.98 per 1,000); 100,000 for $79 ($0.79 per 1,000); 250,000 for $169 ($0.68 per 1,000). Credits never expire, run at standard speed, CSV verification only (no API or finder). |
| Free checks | First 100 email checks free with a Google sign-in, no card, once per account. Single checks on the free email checker need no account. |
| Billing | Monthly subscription, cancel anytime (yearly billing optional). One-time packs are listed above. Starter and Growth allowances reset monthly and do not roll over. |
| Speed today | One sending IP today, shared by every customer: about 13,000 mailbox checks a day in the standard lane. Bad syntax, dead domains and disposable addresses return at once; a list of 100,000 takes days, not hours, and each job shows its estimated finish time. |
| Catch-all handling | Catch-all (accept-all) addresses stay risky, never valid, and are graded higher, medium or lower likelihood with the reasons. Anything a mail server does not confirm is risky. |
| API and MCP | REST API on Pro, Business and Agency (Pro includes 10,000 calls a month, then $1.50 per 1,000). Remote MCP server with 6 tools for Claude, ChatGPT, Cursor and VS Code. No API on Starter or Growth. |
| Integrations | Connects to Instantly, Smartlead, HubSpot and Mailchimp by API key: verifies a campaign or list and tags each contact with its result. CSV in and out for any other tool. |
| Phone | Free phone format checks (country, type range). Live carrier and line-type lookups are a $20/mo add-on (5,000 a month). It never says a number is in service. |
| What it does not do | No sending, warmup or inbox placement tests. No published accuracy benchmark against other verifiers. Catch-all domains, Yahoo and AOL cannot be confirmed, and Outlook.com and Hotmail mailboxes are not probed while Microsoft refuses checks from our server's network: all of these come back risky, never valid. |
SimpleVerifier facts from our pricing page and product. Last updated .
Test it on a real address first
Type any address. It gets the same check the paid plans run: syntax, the domain’s mail servers and, where the provider allows it, a live mailbox check. Nothing is sent to the address.
Five checks a minute, no account needed. Nothing is sent to the address — we ask its mail server whether the mailbox exists, then disconnect.
Have a list? Sign in with Google and the first 100 addresses are checked free, with results to download. No card.
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What SimpleVerifier's API returns
Every response has a status (valid, risky or invalid), a reason, flags for disposable (9,913 domains recognised), role and catch-all addresses, and decision fields: action (send, send_with_care, retry_later or do_not_send), risk (low, medium or high), likely_invented and reason_code. Only valid gives send. Full fields are in the API reference.
Syntax, domain, disposable and mailbox checks run in one call, so there is no cheaper syntax-only tier and no extra charge for the mailbox check.
Limits, said plainly
120 calls a minute per key. On monthly billing, calls past the included number keep working at $1.50 per 1,000; on yearly billing the included calls are a monthly limit, and further calls get HTTP 402 until the 1st (UTC). One address per call; lists go through a CSV upload, which uses no API calls. Starter and Growth have no API access.
A real-time check takes as long as the recipient's mail server takes to answer, so the integration guides set a timeout and accept the address when it is reached: a slow server never blocks a real sign-up. Outlook.com and Hotmail addresses come back risky while Microsoft refuses checks from our server's network.
For AI agents
The same checks are available as a remote MCP server with 6 tools, up to 100 addresses per verify_emails call, for Claude, ChatGPT, Cursor and VS Code on Pro, Business and Agency.
When another API is the better pick
- You want to send a whole list in one request. Ours checks one address per call; lists go through a CSV upload.
- You need more than 120 calls a minute on a single key.
- You only need syntax validation in the browser: the email validation code generator writes that for free, with no API at all.
- A vendor in the table costs less at your volume. The table is sorted by price and lists them as plainly as the ones that cost more.
Common questions
- What is the best email validation API for developers?
- One that probes the mailbox over SMTP, reports unconfirmable addresses as risky instead of valid, and costs least at your volume. SimpleVerifier's Pro is $39 a month with 10,000 calls a month included, then $1.50 per 1,000; the table on this page prices other APIs at 10k, 100k and 1M calls with the dates read.
- Is there a free email validation API?
- API keys come with Pro and up. The first 100 email checks are free in the dashboard with a Google sign-in, and the free email checker needs no account.
- What does 1,000,000 calls a month cost?
- $949 a month on monthly billing: Agency's 300,000 included calls, then $1.00 per 1,000.
- How accurate is the API?
- We publish no accuracy percentage, because we have no independent measurement to back one. Each result carries the reason it was given, and unconfirmable addresses are risky, never valid.
Get an API key
Pro is $39 a month and never cuts you off: the first 100,000 emails a month run at full speed, then big lists run slower. CSV uploads, the API (10,000 calls a month, then $1.50 per 1,000), the Google Sheets add-on and the email finder are included, and you can cancel any time. For smaller volumes, Starter is $9 a month for 2,500 emails a month and Growth $19 a month for 10,000 emails a month.
The first 100 email checks are free with a Google sign-in, no card, on the same engine the paid plans use.