Nuncio vs Superhuman
Superhuman popularized fast keyboard-driven email, wrapped inside a closed cloud client with a recurring subscription. We're building Nuncio as a free, open, local-first alternative: the same keyboard-first ambition, running on a daemon you own.
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.
Superhumanpricing is approximate — pricing as of 2026; check the vendor's site for current rates.
Free & Open, Not a Paid Subscription
Nuncio is MIT / Apache-2.0 with no subscription planned. Superhuman charges a monthly or annual fee across its tiers for its closed cloud client.
Local SQLite, Not Closed Cloud
Synced mail and the search index live in local SQLite WAL files on your disk, owned by a daemon you run — not on Superhuman's servers.
One Contract, Future Clients
A desktop GUI, terminal TUI, and MCP client are planned as thin clients over the same gRPC API the reference CLI already uses.
A Governed AI Gateway
The plan: let AI agents work with your mail through capability policies and an audit trail, not a black-box cloud AI feature.
Why We're Building It This Way
Superhuman's keyboard-driven speed is real, but it's delivered through a closed client on top of centralized cloud servers, for a few hundred dollars a year. Nuncio's architecture takes a different path: one daemon (nunciod) that owns your mail state in local SQLite, speaking a single versioned gRPC contract that a future terminal client, desktop GUI, and AI-agent gateway would all consume identically. The daemon, IMAP/SMTP sync, local FTS5 search, export, and the WORM audit ledger are real and buildable from source today; the additional clients and live NSQL rule-firing are what's ahead.
Design & Architecture Matrix
Nuncio's target design against Superhuman today — planned items are labeled, not claimed as shipped.
| Capability / Dimension | Nuncio | Superhuman |
|---|---|---|
| Pricing & Subscription | Free & open source (in development) | ≈$300+/yr (tiered plans) |
| Data Storage Location | Local SQLite WAL, daemon you run | Proprietary cloud servers |
| Build & Run From Source | Yes | No |
| Scriptable CLI | Yes | No |
| Terminal TUI Interface | Planned | No |
| AI Agent Access (MCP) | Planned | No |
| WORM Audit Ledger | Yes | No |
| NSQL Automation Engine | Author & dry-run test todayIn progress | Basic rules |
| Local Full-Text Search | SQLite FTS5, fully offline | Cloud-side search API |
| At-Rest Body Encryption | Planned | Server-side TLS only |
| Portable Export (MBOX/EML/JSON) | Yes | Limited export |
| Cross-Platform (engine + CLI) | macOS, Windows, Linux | macOS, Web, iOS |
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 Superhuman's ≈$300+ / Year (tiered plans).