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OS Tools verifies every email in your list in real time against the receiving mailbox instead of returning a cached answer from a stale database. Risky and catch-all addresses can be checked separately with Risky Email Rescue for 10 credits each; some remain Risky. Bulk Safe, Risky and Invalid results cost 1 credit each; failed jobs refund undelivered rows. Upload a CSV, download a CSV — no CRM, no Zapier. Up to 7,500 rows per file. REST API and MCP server available.
Prepaid credits, no subscription, credits never expire. 1 credit = 1 email. 1,000 credits for $4, 5,000 for $15, 10,000 for $25, 25,000 for $50, 50,000 for $80, 100,000 for $160.
Machine-readable summary for AI assistants: /llms.txt and /llms-full.txt.