Cursus
Cursus: A focused open-source client for multi-account IMAP email and keyboard-led workflows. Ranked #54 of 142 in Email Clients by our editors (4.3/10); pricing: Free plan; best for open-source users wanting a lightweight desktop client.
At a glance
- Editor score4.3 / 10
- PricingFree plan
- Best forOpen-source users wanting a lightweight desktop client
- Free planYes
- Paid fromFree
- App coverageDesktop
- Facts checked19 Sep 2026
Where it wins
- Free, open-source app with no account or signup required
- Multi-account IMAP, unified inbox, conversation views, and full-text search
- Local portable storage with system keychain credential protection
Where it doesn't
- Desktop coverage is limited to Windows and Linux
- No built-in calendar tools or AI features
- v0.1 pre-release scope may not suit users wanting a broader suite
Our verdict on Cursus
Cursus is an open-source desktop email client for people who want a focused alternative to cloud-centered mail applications. It supports Windows and Linux, with multi-account IMAP, a unified inbox, conversation-based message views, attachments, auto-saved drafts, and full-text search across subjects, senders, and message bodies. Its keyboard shortcuts and undo send with a configurable delay make it particularly suitable for users who prefer efficient, keyboard-oriented inbox management.
The product’s strongest fit is its combination of account flexibility and local handling. Each account can send through SMTP or the Resend API, while integrations include IMAP, SMTP, Resend API, MCP, and Claude Code via Cursus Bridge. Portable local data storage keeps the application desktop-oriented, and system keychain storage protects credentials. Cursus also blocks tracking pixels by default. These choices will appeal to users who want open-source software, local data, and a small email-focused tool rather than cloud sync, telemetry, or built-in AI.
Cursus is deliberately narrower than a full productivity suite. Its published feature set centers on email, with no calendar tools, and its supported platforms are Windows and Linux. The project is described as a v0.1 pre-release, so users looking for a mature, broad account ecosystem or a combined mail-and-calendar application should choose an alternative. For open-source users who need free multi-account IMAP, search, drafts, undo send, and keyboard controls on a desktop, Cursus offers a clear, focused scope without requiring signup.
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Cursus pricing
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Cursus fact sheet
| Free plan | Yes |
|---|---|
| Paid from | Free |
| App coverage | Desktop |
| Account limit | Not verified |
| Unified inbox | Yes |
| Offline access | Not verified |
| Scheduled sending | Not verified |
| Calendar tools | No |
| Deployment | Desktop |
| Platforms | Windows, Linux |
| Integrations | 5 integrations: IMAP, SMTP, Resend API, Claude Code via Cursus Bridge, MCP |
| Pricing | Free plan (source) |
| Website | opencursus.app |
| Facts checked | 19 Sep 2026 |
Cursus integrations
Cursus lists 5 integrations on its own site.
- IMAP
- SMTP
- Resend API
- Claude Code via Cursus Bridge
- MCP
Alternatives to Cursus
- Mozilla ThunderbirdA capable free client for multi-account email, offline access, and desktop productivity tools.9.4
- Zoho MailA flexible hosted email service with free access, migration tools, and Zoho collaboration options.9.2
- Apple MailA capable Apple-focused email client with unified inboxes, scheduling, privacy controls, and AI assistance.9.1
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Reviewed by iTechGuides Editors · Editorial team · Updated Sep 2026
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