Nuncio vs Airmail
Airmail is a polished macOS-only client behind a Pro paywall. We're building Nuncio as a free, open, local-first alternative that runs the same engine on macOS, Windows, and Linux from day one.
Nuncio is pre-alpha. Rows below marked Planned are architecture we are actively building, not something you can use yet — see the roadmap for status.
Airmailpricing is approximate — pricing as of 2026; check the vendor's site for current rates.
Cross-Platform by Design
The engine (nunciod) and reference CLI already build and run on macOS, Windows, and Linux. Airmail is strictly Apple-ecosystem.
Free & Open Source, Always
Nuncio is MIT / Apache-2.0 with no planned subscription tier. Airmail requires an Airmail Pro annual subscription for core multi-account features.
One Contract, Many Future Clients
A terminal TUI and desktop GUI are on the roadmap, both as thin clients over the same gRPC API the CLI already uses — not separate codebases to keep in sync.
NSQL Rules & a WORM Ledger
Write and dry-run test declarative SQL-style filter rules today, and inspect every account/rule mutation in an immutable hash-chained audit log.
Why We're Building It This Way
Airmail's clean interface is locked to Apple hardware, and multi-account syncing sits behind a recurring Pro subscription. Nuncio starts from a different premise: one daemon (nunciod) that owns your mail state locally and speaks a single versioned gRPC contract, so a terminal client, a desktop GUI, and the reference CLI can all be thin, interchangeable clients instead of three separate apps to maintain. The daemon, IMAP/SMTP sync, full-text search, export, and the WORM audit ledger are real and buildable from source today; the additional clients and the NSQL engine's live rule-firing are the next milestones.
Design & Architecture Matrix
Nuncio's target design against Airmail today — planned items are labeled, not claimed as shipped.
| Capability / Dimension | Nuncio | Airmail |
|---|---|---|
| Pricing Model | Free & open source (in development) | $29.99/yr Pro subscription |
| OS Availability (engine + CLI) | macOS, Windows, Linux | macOS & iOS only |
| Build & Run From Source | Yes | No |
| Multi-Account IMAP/SMTP Sync | Yes | Yes |
| Local Full-Text Search | SQLite FTS5, fully offline | Local index |
| Portable Export (MBOX/EML/JSON) | Yes | Basic EML export |
| WORM Audit Trail | Yes | No |
| Terminal TUI Interface | Planned | No |
| Desktop GUI Interface | Planned | Yes |
| Server-Side Rule Engine (NSQL) | Create & dry-run test todayIn progress | Basic mail rules |
| At-Rest Body Encryption | Planned | OS Keychain only |
| HTML Email Sandboxing | Planned | Standard WebKit render |
Watch It Get Built, Don't Just Wait For It
Nuncio isn't installable by end users yet. It will be free and open source under MIT / Apache-2.0 — no account, no subscription, no lock-in vs Airmail's $29.99 / Year Pro Subscription.