# 2 Best Open-Source Alternatives to Fastmail in 2026

By Noah — last updated & pricing verified September 15, 2026.

> 2 of the 5 Fastmail alternatives we list qualify for this filter. The [full list](https://findalternative.to/fastmail) is the canonical page.

| Alternative | Best for | Price | Details |
| --- | --- | --- | --- |
| Proton Mail | privacy-conscious individuals, journalists, and small teams who want end-to-end encrypted email with open-source, independently audited clients rather than a mainstream provider that can technically read stored mail | Free tier · paid from $3.99/mo | https://findalternative.to/proton-mail/about |
| Tuta | privacy-conscious individuals and organizations, including journalists, healthcare providers, and nonprofits, who want end-to-end encrypted email and calendar with open-source, auditable clients | Free tier · paid from $3.25/mo | https://findalternative.to/tuta/about |

All 5 alternatives to Fastmail: https://findalternative.to/fastmail

---

Markdown mirror of https://findalternative.to/fastmail/open-source — findalternative.to, honestly ranked software alternatives. AI info: https://findalternative.to/ai