API V2
Version 2 of the Captain Verify API is now available and it includes new features. If you are looking for a reliable way to verify the validity of your emails, you can integrate Captain Verify's email verification API into your own applications.
API Key
An account is required to generate the key for the API, this is what will give you access to the service.
API limits
The API is limited to a maximum of 2 simultaneous connections and 50 checks per minute. When integrating the API, make sure your application does not exceed this limit.
The request
To make a request to the API, simply call the GET protocol at this URL:
https://api.captainverify.com/v2/verify?apikey=XXXXXXXXXXXXXXXXXXXX&email=john.doe@gmail.com
Replace john.doe@gmail.com with your email to verify.
The answer
A json table will be returned with these variables:
{
"credits":870,
"result":"invalid",
"details":"unknown_email",
"free":true,
"role":false,
"disposable":false,
"ok4all":false,
"protected":false,
"did_you_mean":"john.doe@gmail.com",
"email":"john.doe@gmail.com",
"email_normalized":"john.doe@gmail.com",
"success":true,
"message":null
}
| Variables | Possible value |
|---|---|
| credits | Credits available in your account. |
| result | valid, invalid, risky, unknown The status of the email. if all your credits have been exhausted, the unknown status will always be returned, so as not to block your application. |
| details | null, email error, greylisting, low quality, low deliverability, mailboxfull... Understand the result of an audit. |
| free | true, false If the email provider is free, eg Gmail.com. |
| role | true, false If the email user has a role, ex: support@example.com. |
| disposable | true, false The email is valid, but disposable after a short time it will no longer be possible to contact the user. |
| ok4all | true, false Ok for all: the remote mail server accepts all e-mails (catch-all). |
| protected | true, false The email is protected by a proprietary antispam solution |
| mailboxfull | true, false The email address is full. She can no longer receive mail |
| did_you_mean | default : null If for example, the email is john.doe@gmil.com, the API will send you a proposal like john.doe@gmail.com. |
| The email you want to verify. | |
| email_normalized | Email has normalized, removing tags for gmail...support+test@gmail.com will be support@gmail.com. |
| success | true, false If authentication failed, your credits are exhausted. |
| message | default : null When the success is false, an error message will be sent. |
Why integrate an email verification API?
A contact database degrades quickly. Addresses entered with a typo, disposable emails created to get past a form, mailboxes abandoned and then closed: every invalid address that enters your system ends up as a hard bounce. And bounces are expensive. They inflate your sending bills, distort your campaign statistics and, above all, damage your sender reputation with mailbox providers.
Manual cleaning always comes too late. Once the address is saved in your CRM, it has already polluted your segments, your lead scores and your exports. Programmatic verification reverses the logic: the address is checked at the exact moment of collection, before being stored.
That is exactly the role of an email verification API. You send an address, you receive a verdict your code can act on, and you decide what to do with it: accept, reject or ask the user for a correction. All without human intervention.
API use cases
Real-time validation at signup
Plug the API into your signup, download or quote request forms. Typos (gmail turned into gmial), disposable emails and nonexistent addresses are detected before the record is saved. The user can correct their input immediately, and only valid addresses enter your database.
Bulk cleaning before a campaign
A list that sits idle for a few months accumulates dead addresses. Before a major send, run it through the API to filter out invalid or risky addresses. The result: a controlled bounce rate, reliable campaign statistics and a sending budget focused on recipients who actually exist.
Keeping your CRM reliable
Connect verification to your data entry points: imports, integrations, sales team input. Every contact is qualified as soon as it is created, with a clear status on the validity of its email. Your teams work with clean records and your lead scoring is based on real data.
Protecting sender reputation
Mailbox providers monitor your hard bounces and your sends to spam traps. Too many incidents, and your legitimate emails end up in spam. By filtering out dangerous addresses before every send, the API protects your sender reputation and therefore the deliverability of all your communications.
Frequently asked questions about the API
What exactly does the API check?
Several checks run in sequence: address syntax, existence of the domain and its MX records, then an SMTP test to verify that the mailbox accepts messages. The API also detects disposable emails and role-based addresses (contact@, info@). The response is returned in JSON format.
Does the API work in real time?
Yes. Each request triggers an immediate verification and returns the result right away, which makes it possible to integrate it directly into a form or a signup flow. For large volumes, full file verification remains available from your account.
How much does it cost?
Billing works with credits: one verification uses one credit, with no mandatory subscription. Purchased credits can be used for both the API and file verification. Details on volumes and tiered pricing are available on our pricing page.