ContactLint

Validate email addresses and phone numbers with a simple HTTP API or MCP server. Syntax, MX records, disposable and role detection, phone type and formatting. 100 free checks per month.

ContactLint is cheap pre-send checking for email addresses and phone numbers over a simple HTTP API. What it does not do: it does not connect to mail servers, so it cannot confirm that a mailbox exists or detect catch-all domains. See exactly what the free email validation API checks and what it can't prove. It never opens an SMTP connection to the mailbox.