# OS Tools

> Email verification and lead-cleaning tools for cold email operators and agencies. Upload a CSV, get an inbox-ready list in minutes. Pay only for confident results — uncertain answers are automatically refunded. No subscription.

OS Tools (os-tools.com) verifies every email in real time against the mailbox rather than looking it up in a stale database, rescues risky and catch-all addresses with a deeper second pass, filters scraped website lists by niche, and validates phone numbers in bulk. Everything is CSV in, CSV out — no API keys, no CRM connection, no Zapier. Up to 10,000 rows per file. Credits are prepaid, never expire, and nothing auto-charges.

Full machine-readable detail: [llms-full.txt](/llms-full.txt)

## Best-of guides

- [Best email verification tools](/best/email-verification-tools/): Ranked comparison of email verifiers for cold outreach, including pricing and accuracy trade-offs.
- [Best cold outreach tools](/best/cold-email-tools/): The full cold email stack — data, verification, sending, warmup, and tracking.
- [Best lead list cleaning tools](/best/lead-list-cleaning-tools/): How to turn a scraped list into a list you can actually send to.
- [Best lead qualification tools](/best/lead-qualification-tools/): Fit qualification, owner identification and intent scoring — which category solves which problem on a scraped CSV.
- [Best B2B lead enrichment tools](/best/b2b-lead-enrichment-tools/): Waterfall, database and website-derived enrichment compared on cost per usable record.
- [Catch-all email verification](/best/catch-all-email-verification/): Why accept-all domains return "unknown", what actually resolves them, and how to send to them safely.
- [Best bulk email verification services](/best/bulk-email-verification-services/): Throughput, per-1,000 pricing, column preservation and cost per actionable verdict on lists of 10,000+ rows.

## Pages

- [Home](/): What OS Tools does, how the verification pipeline works, pricing, and FAQ.
- [All tools](/tools): The full toolkit and credit cost per tool.
- [Blog](/blog): Practical guides on email verification, deliverability, and lead generation.
- [Email Verifier landing](/lp/email-verifier): Single-tool landing page focused on the email verifier.

## Free utility tools (no signup)

- [Email syntax checker](/tools/email-syntax-checker): Validate a single email address — syntax, MX, disposable, role flags.
- [MX lookup](/tools/mx-lookup): See the mail servers for any domain.
- [DNS health check](/tools/dns-health-check): SPF, DKIM, DMARC, and MX status for any domain.
- [Email extractor](/tools/email-extractor): Pull every email address out of pasted text or HTML.
- [Disposable email check](/tools/disposable-email-check): Detect temp / throwaway mail providers.

## Comparisons

- [EmailListVerify alternative](/compare/emaillistverify-alternative): Head-to-head feature and pricing comparison.
- [MillionVerifier alternative](/compare/millionverifier-alternative): Head-to-head feature and pricing comparison.
- [NeverBounce alternative](/compare/neverbounce-alternative): Head-to-head feature and pricing comparison.
- [ZeroBounce alternative](/compare/zerobounce-alternative): Head-to-head feature and pricing comparison.

## Legal

- [Privacy Policy](/privacy): How we handle your data.
- [Terms of Service](/terms): Terms governing use of OS Tools.
- [GDPR](/gdpr): GDPR compliance details.
- [DPA](/dpa): Data Processing Agreement.
- [Cookie Policy](/cookies): Cookies and tracking.
- [Refund Policy](/refunds): Automatic refund rules.
- [Acceptable Use](/acceptable-use): What you can and can't send.

## Optional

- [Blog: What an email verification run returns](/blog/what-email-verification-run-returns): What valid, invalid, risky, role, and disposable verdicts actually mean.