Email Rebuilt for Today.
Private, Fast & AI-Integrated.
No paid subscriptions, closed formats, or locked-away data. Enjoy four extraordinary interfaces, AI NSQL filters, and cryptographic audit logs without losing control of your data.
Urgent Architecture Review & VIP Release
MCP Calendar Event Confirmation: Architecture Alignment
Multi-Platform Nightly Build #30031303002 Succeeded
Urgent Architecture Review & VIP Release
From: Alice Vance (Kof22)
Please review the Nuncio sovereign mail architecture spec for 100% parity across all 4 interfaces...
Email Rebuilt for Today.
Private, Fast & Secure.
Break away from paid cloud subscriptions, closed proprietary formats, locked-away data, and fragmented user experiences across platforms.
1. Sane & Controlled AI Access
AI co-pilots should empower you, not exfiltrate your life. McpAgentPolicy enforces granular RBAC capability flags, folder boundaries, and automatic SSN/credit card redaction before any payload touches an LLM.
2. First-Class UI/UX in Every Space
No second-class interfaces. Enjoy equal polish across native macOS glassmorphism, Windows, Linux, Vim Ratatui Terminal TUI, POSIX scriptable CLI, and native MCP AI agent integration with 100% feature parity.
3. Uncompromising Speed & Performance
Engineered in native Rust over single-writer SQLite WAL storage. Search 100,000+ emails in under 10 milliseconds, execute NSQL rules in microsecond time, and run with zero battery drain.
4. Sovereign Control & Zero Closed Formats
No cloud lock-in, no proprietary sync servers, no closed formats. Your emails, accounts, rules, and calendars stay in standard local SQLite files on your disk. You own your data 100%.
5. Zero-Trust Security & Encryption
Column-level AES-256-GCM data-at-rest encryption (PayloadCipher), age X25519 attachment ciphers, ZeroizeOnDrop memory page locking, and HTML email sandboxing with tracking pixel neutralization.
6. WORM Cryptographic Audits
Every automated rule match, webhook dispatch, account mutation, and AI MCP tool call is recorded in an immutable Write Once Read Many (WORM) audit ledger sealed with HMAC-SHA256 hash chains.
One Engine. Four Ways to Work.
Whether you prefer a sleek desktop window, lightning terminal keybindings, Unix shell scripts, or AI co-piloting — Nuncio fits your exact daily workflow.
1. The Desktop Workspace (Featured GUI)
Beautiful Visual Elegance for Everyday Productivity
The primary desktop application designed for seamless daily flow. Enjoy a clean, distraction-free inbox with rich email previewing, visual calendar scheduling, and drag-and-drop filter creation.
- Sandboxed HTML email inspector with automatic tracking pixel neutralization
- Unified inbox for all your personal, work, and custom domain accounts
- Visual drag-and-drop rule builder and interactive calendar planner
- Blazing-fast native performance with minimal RAM and battery usage
2. The Vim Keyboard Terminal (Ratatui TUI)
Keyboard Velocity for Triage Without Touching the Mouse
Built for developers and power users who demand maximum speed. Process hundreds of inbox messages per minute using intuitive Vim motions, single-key triage chords, and split-view previews.
- Vim navigation (`j`/`k`/`h`/`l`/`g i`) & single-key archive/delete chords
- Instant split-pane previewer for text & HTML email content
- Interactive NSQL rule editor & dry-run condition tester built-in
- Runs directly in any terminal tab or SSH session
3. The Developer Command Shell (POSIX CLI)
Instant Inbox Queries & Automation Right From Your Shell
Designed for developers, sysadmins, and shell enthusiasts who want effortless scriptability. Search messages, query calendar availability, and trigger custom webhooks directly from command scripts.
- Pipeable JSON outputs for shell scripts & custom automations (`--json`)
- Instant search across 100,000+ messages in under 10 milliseconds
- Headless background sync daemon (`nunciod`) keeps mail updated silently
- Simple single-command email dispatching & account management
4. The AI Executive Assistant (MCP Agent)
AI Co-Pilots Working Alongside You with Granular Privacy
Aggregate ALL your email accounts into one local hub. Connect local LLMs and AI agents (Claude, Antigravity, Cursor) through Nuncio's security gateway—never granting uncontrolled direct credentials to Gmail or IMAP. Controlled via WORM audits, RBAC policies, and microsecond SQLite speed.
- Aggregate unlimited IMAP, JMAP & Gmail accounts into a single local vault
- Controlled AI Gateway: Zero uncontrolled direct access to raw email providers
- Immutable HMAC-SHA256 WORM audit ledger logs every AI tool call & email read
- Sub-10ms local FTS5 search delivers microsecond speed without cloud fees
Live Interactive NSQL Rule Evaluator
Edit the NSQL query below and run a real in-browser AST evaluation against sample inbox messages with zero mock hardcoding.
Real Dry-Run Evaluation Output
Edit the query in the editor and click "Run Dry-Run Preview" to parse your NSQL text and evaluate real condition matches against sample email envelopes.
Security Enforcement Guarantees
- 100% Parameterized Binding (`sqlx::QueryBuilder`) — Zero SQLi.
- DFA Regex Evaluation with 50ms Hard Timeout — Zero ReDoS.
- Pre-flight DNS Blacklist — Zero SSRF to 127.0.0.1 or cloud metadata.
- HMAC-SHA256 Cryptographic Hash Chain Audit Ledger.
Built for those who demand more.
See how Nuncio outperforms traditional desktop clients and expensive cloud subscriptions across Mac, Windows, and Linux.
Nuncio vs Airmail
Compare Nuncio to Airmail for Mac and iOS.
Nuncio vs Canary Mail
Compare Nuncio to Canary Mail AI email.
Nuncio vs Spark Mail
Compare Nuncio to Spark Premium Desktop.
Nuncio vs Superhuman
Why pay $360/yr when Nuncio is 100% free?
Nuncio vs HEY Mail
Sovereign local privacy vs closed HEY servers.
Nuncio vs Apple Mail
4 interfaces & NSQL filtering vs Apple Mail.
Nuncio vs Outlook 365
Microsecond SQLite speed vs Outlook telemetry.
Nuncio vs Mozilla Thunderbird
Modern Rust architecture vs legacy Thunderbird.
Nuncio vs Gmail
100% zero-tracking privacy vs Gmail data mining.
One Core Engine. Four Great Interfaces.
Every feature in Nuncio is implemented 1:1 across POSIX CLI, Vim Ratatui TUI, Desktop GUI, and Native MCP LLM Agent interface without shells or mocks.
| Capability | CLI | TUI | GUI | MCP | Status |
|---|---|---|---|---|---|
List Accounts Account Management | nuncio account list | AppMode::AccountSettings | Configured Accounts List | nuncio_account_list | 100% PARITY |
Add Account Profile Account Management | nuncio account add | [a] Add Account Modal | Add Account Form | nuncio_account_add | 100% PARITY |
Edit Account Config Account Management | nuncio account edit | [e] Edit Account Modal | Inline Edit Form | nuncio_account_edit | 100% PARITY |
Delete Account Profile Account Management | nuncio account delete | [d] Delete Account Modal | Remove Account Button | nuncio_account_delete | 100% PARITY |
Test TLS Connectivity Account Management | nuncio account test | [t] Test TLS Connection | Test Connection Button | nuncio_account_test | 100% PARITY |
Sync Mailboxes Email Operations | nuncio mail sync | Sync (s) | Sync Button | CoreCommand::SyncAll | 100% PARITY |
Search Messages (FTS5) Email Operations | nuncio mail search | Search Mode (/) | Filter & Search Input | nuncio_mail_search | 100% PARITY |
Send Email / Outbox Email Operations | nuncio mail send | Compose Modal (c) | Compose Modal Component | nuncio_mail_send | 100% PARITY |
List Rules NSQL Automation | nuncio filter list | AppMode::FilterRules | <FilterRulesModal /> List | nuncio_filter_list | 100% PARITY |
Create NSQL Rule NSQL Automation | nuncio filter create --sql | [n] New Rule / [s] Code | <RuleBuilderForm /> | nuncio_filter_create | 100% PARITY |
Dry-Run Preview NSQL Automation | nuncio filter test --sql | [t] Dry-Run Previewer | <ConditionTester /> Pane | nuncio_filter_test | 100% PARITY |
Execution Audit Logs NSQL Automation | nuncio filter logs | [l] Log Drawer | <AuditLogInspector /> Tab | nuncio_filter_logs | 100% PARITY |
List Calendar Events Calendar & Scheduling | nuncio cal list | Agenda / Calendar Pane | Calendar Grid View | nuncio_cal_list_events | 100% PARITY |
Create Event Calendar & Scheduling | nuncio cal create | Event Creation Modal | Event Creator Component | nuncio_cal_create_event | 100% PARITY |
Column AES-256-GCM Security & Vault | PayloadCipher | PayloadCipher | PayloadCipher | PayloadCipher | 100% PARITY |
OS Keyring Vault Security & Vault | keyring crate | keyring crate | keyring crate | keyring crate | 100% PARITY |
Privacy and Security by Design.
Nuncio implements column-level encryption at rest, secure memory zeroing, sandboxed web rendering, and cryptographic audit ledgers.
AES-256-GCM & age Stream Cipher
Email bodies are encrypted using column-level AES-256-GCM via PayloadCipher. Large binary attachments are encrypted using modern age X25519 stream ciphers with 64KB chunk authentication.
- Zero unencrypted text written to disk
- Memory page zeroing via
ZeroizeOnDrop
OS Keyring Credential Vault
Passwords, OAuth 2.0 refresh tokens, and age private keys are stored exclusively in native OS credential enclaves (Windows Credential Manager, macOS Keychain, Linux Secret Service).
- Zero secrets in SQLite WAL files
- Hardware Security Key (PKCS#11 / YubiKey) ready
Cryptographic Hash-Chain Ledger
Every filter action, webhook payload, and triage mutation writes an immutable entry linked via HMAC-SHA256 hash chains (H_n = HMAC(K, H_n-1 || data)).
- Automated chain integrity verification
- Tamper-evident operational audit trail
Sane & Controlled AI Agent Architecture
Tie all your accounts together in a single place—and control exactly how local LLMs access your data via security policies, WORM audits, and microsecond SQLite speed.
1. Unified Multi-Account Aggregation Hub
Aggregate all your email accounts—unlimited IMAP, JMAP, Gmail, Google Workspace, iCloud, and custom domain accounts—into a single local SQLite storage vault.
2. Controlled Gateway (Zero Uncontrolled Access)
Local LLMs and AI agents NEVER get raw passwords or direct, uncontrolled access to your Gmail or IMAP accounts. All AI actions pass strictly through Nuncio's security enclave with McpAgentPolicy RBAC and automatic PII redaction.
3. WORM Audits & NSQL Filtering
Every single AI agent tool call, email read, draft generation, and send action is logged in an immutable Write Once Read Many (WORM) audit ledger sealed with HMAC-SHA256 hash chains.
4. Microsecond Local Speed
Instant local FTS5 trigram search (<10ms across 100,000+ messages). Local LLMs get sub-millisecond context retrieval without network latency or cloud API fees.
Claude Desktop / Antigravity Config (`claude_desktop_config.json`)
Executable: nuncio-mcp --stdio{
"mcpServers": {
"nuncio": {
"command": "nuncio-mcp",
"args": ["--stdio"],
"env": {
"NUNCIO_LOG_LEVEL": "info"
}
}
}
}Complete Documentation Hub
From installation and Google OAuth PKCE to NSQL grammar specs, HMAC webhooks, and AI MCP integration — explore all 10 technical guides in our dedicated docs portal.
Quickstart & Installation
Account Setup & Providers
Four Shells & Vim Keybindings
NSQL Language Specification
Outbound Signed Webhooks
Native MCP AI Server Setup
HTML & Image Rendering Guide
Universal Data Export & Backups
WORM Cryptographic Audits
Database Corruption Recovery
Available for macOS, Windows & Linux
Free and open-source under MIT & Apache-2.0 licenses. Choose your preferred installer or package manager below.
macOS Universal
Supports Apple Silicon (M1/M2/M3/M4) & Intel x64.
Windows 10 / 11
Native WiX Installer (.msi) with Windows Keyring support.
Linux Standalone
Universal AppImage & Tarball for Ubuntu, Fedora, Arch.