Developer
REST API documentation
A clean, no-nonsense REST API for verifying email addresses in real time or in bulk.
Using the email verification API
Authentication and workflows
Create a workspace API key in Settings → API and send it in the x-api-key header. Keep secret keys on your server. Verify one email address and poll its status if it is still running, or upload a CSV, track the task, and retrieve the file results.
The public OpenAPI specification defines the endpoints, parameters, and response schemas used by the reference below. Reading the specification does not require a key.
Outcomes and credits
Results use four outcomes: valid, invalid, catch_all, and unknown. Catch-all means the domain accepts arbitrary recipients, so the specific mailbox is unconfirmed. Unknown means the check was inconclusive; it does not mean invalid.
Valid and invalid results cost one credit each. Catch-all and unknown results cost nothing. Bulk uploads reserve one credit per deduplicated row and settle to the billable results when complete. See email verification pricing for advertised plans.