What Will an Email Verification API Cost Per Month? Work It Out From Your Signups

Your API bill is the number of calls you make in a month, minus what the plan includes, times the overage price. On SimpleVerifier, Pro ($39 a month) includes 10,000 calls, then $1.50 per 1,000; Business ($99) includes 100,000, then $1.00 per 1,000; Agency ($249) includes 300,000, then $1.00 per 1,000. So the work is counting your real calls, which are usually more than your signups.

Sources: our API docs and pricing, read 3 November 2026.

Step 1: count your calls

Where calls come from	How to count
Signup or lead forms	Monthly form submissions, not visitors. One call per submit if you check on submit only
Checkout or account email changes	Monthly orders or profile edits that change the email
CRM or automation (Zapier, Make, n8n, HubSpot workflows)	New contacts created a month in that tool
Imports via the API	Rows you send. For big files, the CSV upload is the better route
Retries	Calls your code repeats after timeouts or 429s

Add them. A SaaS with 3,000 signups and 1,000 CRM imports a month makes about 4,000 calls, inside Pro's 10,000.

Step 2: pick the plan from the number

Calls a month	Pro	Business	Agency
10,000	$39	$99	$249
30,000	$69	$99	$249
50,000	$99	$99	$249
100,000	$174	$99	$249
250,000	$399	$249	$249
400,000	$624	$399	$349

Pro plus overage reaches Business's price at 50,000 calls a month; Business plus overage reaches Agency's at 250,000. These figures are monthly billing. On yearly billing there's no overage: the included calls are the month's limit and further calls return 402, with a Retry-After header counting down to the 1st (UTC). If you're near the line on yearly, pick the plan above.

Step 3: stop paying for calls you don't need

1. Validate syntax in the browser. Missing @, spaces and obvious typos need no API call. The validation code generator writes the check for your stack.
2. Call once, on submit or blur. Never per keystroke.
3. Don't re-verify the same address on every login or edit. Store the result and its date; re-check when it's weeks old or the address changes.
4. Respect 429s. Each key can make 120 calls a minute over a sliding 60-second window. Retry after the Retry-After seconds, not in a tight loop; handling verification API rate limits has the pattern.
5. Send big batches as a CSV, not as thousands of single calls. Bulk-verify a CSV with the API covers when each route fits.

A single mailbox check can wait up to about 30 seconds on a slow mail server, so set your client timeout with that in mind and don't count a timed-out call twice by retrying immediately.

Limits

The included calls are per month and don't roll over. The API isn't unlimited on any plan. Some results will be risky or unknown because catch-all and slow servers don't give a clear answer; decide in advance what your form does with those (we suggest accepting them and flagging them). A verification API also can't tell you whether the person typing is who they say they are; for bots, see stop fake signups.

Where SimpleVerifier fits

Create a key after subscribing and start with the API docs; real-time verification on signup forms covers latency. The first 100 checks are free with a Google sign-in at /verify, so you can see the result format first. Pro is $39 a month with the first 100,000 checks a month at full speed, then slower, never cut off, plus 10,000 API calls. See pricing.