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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 go through a deeper second pass that settles them as safe or invalid, and any result we can't stand behind refunds its credit to your balance automatically. Upload a CSV, download a CSV — no API keys, no CRM, no Zapier. Up to 10,000 rows per file.
Prepaid credits, no subscription, credits never expire. 1 credit = 1 email. 5,000 credits for $15, 25,000 for $50, 100,000 for $140, 250,000 for $250.
Machine-readable summary for AI assistants: /llms.txt and /llms-full.txt.