head to head · open source
Inbox Zero vs Hyvor Relay
Inbox Zero has 12,895 GitHub stars, 1,653 forks, 209 open issues and last shipped yesterday. Hyvor Relay has 920 stars, 65 forks, 56 open issues and last shipped yesterday. Inbox Zero leads on adoption by 1,302% (12,895 vs 920 stars). Inbox Zero is written in TypeScript under a custom or non-standard licence; Hyvor Relay is written in PHP under AGPL-3.0. Inbox Zero has attracted 13% as many forks as stars, Hyvor Relay 7%. Inbox Zero was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 1 topic tag (email), so they are genuine substitutes rather than adjacent tools.
Two open source projects, one decision. Both are free and self-hostable — the differences are community size, license terms, language stack and release pace.
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Side by side
| Inbox Zero | Hyvor Relay | |
|---|---|---|
| GitHub stars | ★ 13K | ★ 920 |
| License | Custom / other | AGPL-3.0 |
| Written in | TypeScript | PHP |
| Last push | 2026-11-02 | 2026-11-02 |
| Forks | ⑂ 1.7K | ⑂ 65 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Inbox Zero if
- You weight community size — 13K stars and counting
- You want the Custom / other license terms
- Your stack matches TypeScript
- You value the larger contributor base for long-term maintenance
pick Hyvor Relay if
- You want the Hyvor Relay feature set and don't need the biggest community
- You prefer the AGPL-3.0 license terms
- Your stack matches PHP
- You evaluated both and Hyvor Relay fits your workflow better
About Inbox Zero
Inbox Zero your 24/7 AI email assistant Organizes your inbox, pre drafts replies, manages your calendar, and organizes attachments. Chat with it from Slack or Telegram to manage your inbox on the go. Open source alternative to Fyxer, but more customizable and secure. Website · Discord · Issues Mission To help you spend less time in your inbox, so you can focus on what matters most. Features AI Personal Assistant: Organizes your inbox and pre drafts replies in your tone and style. AI Rules for email: Explain in plain English how your AI should handle your inbox. Reply Zero: Track emails to reply to and those…
read the full Inbox Zero overview →
About Hyvor Relay
Hyvor Relay Hyvor Relay is a self hosted, open source email API for developers. It uses SMTP to send emails using your own infrastructure. It is designed to be simple to self host, easy to manage and observe, and powerful enough to send millions of daily emails. Email API for Developers Self Hosting Docs Product Docs Features Self Hosted : Docker compose or swarm based deployment. Health Checks : Multiple health checks to ensure best performance and deliverability. Email API : Send emails using a simple API. Logs & SMTP Conversations : View send logs and SMTP conversations of sent emails up to 30 days. Multi…
read the full Hyvor Relay overview →
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Frequently asked questions
Is Inbox Zero or Hyvor Relay more popular?
Inbox Zero has 12,895 GitHub stars and Hyvor Relay has 920. Inbox Zero has the larger community by that measure.
Are Inbox Zero and Hyvor Relay free?
Both are open source. Inbox Zero has no licence declared in this registry, and Hyvor Relay is licensed under AGPL-3.0. Both are free to self-host.
What is the difference between Inbox Zero and Hyvor Relay?
Inbox Zero is written in TypeScript and Hyvor Relay in PHP. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, Inbox Zero or Hyvor Relay?
Choose Inbox Zero if you want the larger community (12,895 stars) or its Custom / other licence terms. Choose Hyvor Relay if its feature set, stack or AGPL-3.0 licence fits better. Both are self-hostable.