Haraka Review, Pricing & Features

Haraka is a free open source Node.js SMTP server with a plugin architecture. Read our 2026 review of features, use cases, pros, cons and alternatives.

Researched and fact-checked by Bartu Cavusoglu · Updated July 18, 2026

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Category
Communication
Pricing
Open Source / Free, from Free
Verified
Not yet
Last updated
July 18, 2026
Founded
2011
Free PlanAPIOpen SourceSelf-Hosted

Overview

Haraka is a free, open source SMTP mail server written in Node.js, built for high-throughput, asynchronous mail handling with a fully extensible JavaScript plugin architecture, released under the MIT license.

Created by Matt Sergeant in 2011 and inspired by the Qpsmtpd mail server, Haraka is community-maintained on GitHub with no corporate owner, currently led by maintainer Matt Simerson.

Key Features

Haraka's event-driven, non-blocking architecture lets a single server process handle thousands of simultaneous SMTP connections, with behavior customized entirely through JavaScript plugins hooked into each stage of the SMTP transaction.

A large plugin registry covers authentication, DKIM signing, DNS blocklist checking, SpamAssassin and rspamd integration, and ClamAV antivirus scanning, and Haraka can run as either an inbound filtering gateway or an outbound submission agent.

Pricing

Haraka is completely free and open source under the MIT license, with no paid tiers, commercial edition or vendor lock-in.

Anyone can download, modify, self-host and redistribute Haraka without cost, and there is no company selling a hosted or supported commercial version.

Key Features

Pros & Cons

Pros

  • Free and open source under the permissive MIT license
  • Handles very high SMTP connection volume and throughput
  • Highly extensible through a JavaScript plugin architecture
  • Long track record in production since 2011
  • Battle-tested at scale by companies like Craigslist

Cons

  • Requires Node.js and JavaScript expertise to configure and extend
  • No official graphical management dashboard
  • Documentation is community-maintained and can be sparse in places
  • Not a hosted or managed SaaS, so self-hosting carries operational burden
  • Smaller community and install base than Postfix or Exim

Pricing

Frequently Asked Questions

What is Haraka?

Haraka is a free, open source SMTP mail server written in Node.js, designed for high-throughput, asynchronous mail handling with a fully extensible JavaScript plugin architecture.

Is Haraka free?

Yes, Haraka is completely free and open source under the MIT license, with no paid tiers or commercial edition.

Who maintains Haraka?

Haraka was created by Matt Sergeant and is now community-maintained on GitHub, currently led by maintainer Matt Simerson.

What is Haraka used for?

Haraka is used to operate high-throughput inbound mail filtering gateways or outbound mail submission agents, and is used in production by companies like Craigslist.

Does Haraka support spam filtering?

Yes, Haraka integrates with SpamAssassin and rspamd for spam scoring and supports DNS blocklist checking through plugins.

Can I write custom plugins for Haraka?

Yes, Haraka's behavior is customized entirely through JavaScript plugins that hook into each stage of the SMTP transaction.

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