xiry.

Development · GitHub repo

Reacher

Open-source Rust email verification tool and REST API backend

From the Xiry library · Updated 3 October 2026

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Reacher (formerly check-if-email-exists) is an open-source Rust library and REST API that verifies whether an email address exists without actually sending a message. It checks syntax, MX records, catch-all settings, disposable domains, and SMTP reachability, and can be self-hosted for free or used as a managed SaaS.

What it's for

  • Verify email lists before sending outreach campaigns to reduce bounce rates
  • Validate user emails in real time during sign-up to prevent spam accounts
  • Self-host an internal email verification backend to eliminate third-party SaaS costs

Features

  • Syntax validation following RFC specifications
  • DNS and MX record lookup
  • Disposable and temporary email domain detection
  • SMTP mailbox existence check without sending an email
  • Catch-all address detection
  • REST API backend with client SDK examples in Node.js, Python, and Go
  • Optional managed SaaS and SMTP proxy rotation infrastructure

Pricing

Open source. Free and open source (MIT license) to self-host; paid managed SaaS and proxy plans available

Details

Type
GitHub repo
Category
Development
Topic
Email Verification
Open source
Yes
Platforms
Self-hosted, API, Code library, Linux
For
Developers and growth engineers building email verification into apps or outreach pipelines
Alternative to
NeverBounce, ZeroBounce, MillionVerifier, Hunter
Tags
email verification, rust, smtp, deliverability, self hosted, rest api

Why it was saved

  • @mahanaicoach, 21 September 2026: Serves as a free, self-hostable alternative to paid email verification tools like MillionVerifier to clean cold email lead lists and avoid high verification fees.

Related

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