Buyer guide · SimpleVerifier Team
Email verification for SaaS sign-up forms (API)
SaaS teams call a verification API from the sign-up form to catch mistyped, disposable and non-existent addresses before an account is created. SimpleVerifier returns valid, risky or invalid with a reason for each address. Pro is $39 a month and includes 10,000 calls a month included, then $1.50 per 1,000. The first 100 checks are free with Google sign-in, no card.
Every fake address at sign-up becomes a welcome email that bounces, an onboarding sequence that goes nowhere and a trial that skews your activation numbers.
The API reference covers authentication and the response fields, and the quickstart has working samples. The endpoint is https://simpleverifier.com/api/v1/verify.
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); 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 allowances reset monthly and do not roll over.
- Speed today
- Capacity is shared by every customer: plan on about 13,000 mailbox checks a day in the standard lane (more when the queue is quiet). 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.
- 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 come with Pro + Phone at $49.99/mo (5,000 a month). It never says a number is in service.
- Privacy and GDPR
- Data processing agreement countersigned on request (/dpa). Results files deleted 7 days after a list is submitted; confirmed results cached by address for 14 days. Lists are not used for marketing, sold or shared. Verification runs on a US server. No GDPR certification is claimed.
- 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.
By continuing you agree to our Terms and Privacy Policy.
The sign-up form problem
Sign-up forms attract typos, throwaway mailboxes and bots. A throwaway address is deliverable for ten minutes, so syntax checks alone pass it. Then your first lifecycle email bounces and your sending reputation takes the hit.
A check in the request path must also be safe: a slow mail server should never stop a real person from signing up.
How SimpleVerifier handles it
Call the API on blur or on submit. Invalid results ("Mailbox not found", "No mail server") can ask the user to fix the address, and "Disposable address" can block or flag the account. Risky results, such as "Accepts all addresses", are usually let through. If the call times out, let the sign-up continue and re-check later.
Existing users can be cleaned in one pass: export them as a CSV and upload it, which does not use API calls.
Every result is valid, risky or invalid with a plain reason beside it, such as "Mailbox exists", "Mailbox not found", "Accepts all addresses", "Disposable address", "No mail server", "Server would not confirm" or "Provider hides mailbox status".
Which plan fits, and what it costs
Starter is $9 a month for 2,500 checks; unused checks don't roll over. Pro is $39 a month with no per-email credits: never cut off: the first 100,000 emails a month run at full speed, then big lists run slower. SaaS teams and developers usually start on Starter for a single list and move to Pro once lists arrive every month. The first 100 checks are free with a Google sign-in, no card, on the same engine the paid plans use.
Pro includes 10,000 calls a month included, then $1.50 per 1,000. CSV cleans in the dashboard don't draw on API calls. The same checks are available to AI agents over MCP at https://simpleverifier.com/api/mcp.
How long it takes
Mailbox checks are paced, because mail servers slow down or block verifiers that probe too fast, and the daily check capacity is shared between customers. Addresses that need no mailbox check, such as broken syntax, dead domains and disposable addresses, come back at once. The rest run in a queue, and the job card shows an estimated finish time. Start the check before the send is due, and you can close the tab: the results wait in your history.
Common questions
- Should I block risky addresses at sign-up?
- Usually not. Risky means the server could not confirm the mailbox, not that it is fake, and blocking would turn away real users at catch-all companies.
- What happens if I go over the included API calls?
- On monthly billing, calls past the included number keep working at the per-1,000 price. On yearly billing the included calls are a monthly limit, and further calls get HTTP 402 until the 1st (UTC).
- How do I try it first?
- The first 100 checks are free with a Google sign-in, no card, on the same engine the paid plans use.
- What does it cost?
- Starter is $9 a month for 2,500 checks, or Pro at $39 a month: never cut off: the first 100,000 emails a month run at full speed, then big lists run slower. Plans are monthly or yearly and cancel from your account.
Validate sign-ups with the API
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.
The first 100 email checks are free with a Google sign-in, no card, on the same engine the paid plans use.