Your email client shouldn't slow you down — or compromise your privacy. Lightspeed is the keyboard-first, AI-powered client for Microsoft 365 built for power users and organizations who move fast and own their data.
Every millisecond counts. Lightspeed eliminates friction between you and your inbox with features designed for maximum velocity.
Sub-100ms response times. Eager prefetching loads email bodies before you click. Local SQLite cache with offline support.
60+ Vim-style shortcuts. J/K to browse, R to reply, E to archive. Command palette with Cmd+K. Never touch your mouse.
Full-text search plus AI-powered semantic search. Ask a question and get an AI-crafted answer with cited email sources.
Snooze emails with natural language. Schedule sends for optimal delivery. Undo send with a countdown.
From Nord to Dracula, Catppuccin to Outlook Classic. Dark, light, and specialty themes — all crafted for legibility.
AI-powered inbox splitting. Focused and Other tabs automatically filter your mail so you see what matters first.
Offline voice input powered by Whisper AI. Dictate in the composer with zero cloud latency and total privacy.
Create reusable text snippets with variables. Type a shortcut, expand instantly. Reply to common emails in seconds.
See your O365 calendar alongside email. Day and week views with event creation. Drag, click, done.
Know when your email was opened. Track engagement without third-party tools. Built right into the compose flow.
Add comments to email threads without forwarding. Collaborate on responses without ever leaving your inbox.
Track your daily email productivity. Emails read, sent, archived, AI drafts used — all in a sleek sidebar widget.
Vertical split, horizontal split, wide list, or compact mode. Save layout presets and customize columns.
Drag messages to sidebar folders for instant organization. Visual feedback with undo support for every action.
See company logos, LinkedIn profiles, and sender context at a glance. Know who you're emailing before you reply.
Built-in task board with kanban columns. Create tasks from emails, set due dates and priorities, and track everything in one place.
Powerful email rules with complex conditions. Auto-move, label, flag, or run scripts. Import and export rules as JSON.
Multi-step email sequences with configurable delays. Automatic follow-ups that pause when you get a reply.
Event-driven automation on receive, send, move, tag, archive, or delete. Run scripts or trigger webhooks automatically.
Chain multiple shortcuts into a single key sequence. Record macros with configurable delays between actions.
Auto-remind when emails go unanswered. Per-sender defaults, no-reply detection, and recurring reminders built in.
See job title, company, and photo from Microsoft directory and contacts. Full sender context without switching apps.
Detects unsubscribe links automatically. One click to unsubscribe from newsletters and marketing emails.
Unlike other email clients, Lightspeed does not route your credentials or data through our servers. There is no centralized authentication, no telemetry, and no middleman. You bring your own Azure AD app registration, your own API keys — and everything stays under your organization’s control.
Register your own Azure AD application and connect directly to your Office 365 tenant. Lightspeed never sees your credentials or tokens.
Authentication happens directly between your device and Microsoft. We are not a verified publisher in any ecosystem — by design. Your admin controls permissions.
AI features are powered by your own Gemini API key. Voice transcription runs offline via Whisper. No data leaves your machine unless you explicitly configure it.
Email cache, search index, embeddings, settings, and tokens are stored locally on your device. Uninstall and everything is gone — no cloud residue.
Designed for teams and enterprises that demand privacy and control. IT admins register the app once, grant consent, and users are good to go.
There is no other email client that combines Superhuman-level speed, full AI capabilities, and zero-trust privacy architecture. Lightspeed is in a category of its own.
A note on ecosystem verification: Lightspeed is not currently a verified publisher with Microsoft, Google, or any app marketplace. This is intentional. We believe organizations should control their own app registrations and API permissions rather than delegating trust to a third party. You register the app in your Azure AD tenant, you decide what permissions to grant, and you control who has access.
Every action is one or two keystrokes away. Navigate, reply, archive, search — all without reaching for the mouse.
From arctic cool to warm sepia. Every theme is tuned for readability and designed to make your inbox feel like home.
AI works in the background so you move faster. Ask questions about your inbox, get answers with cited sources, draft replies, and hear responses read aloud — all in an instant.
AI analyzes the conversation and drafts a contextual reply before you even start typing. One click to send.
Three intelligent reply options appear instantly. Pick one, customize, and send in seconds.
Long threads distilled to a single sentence. See the key points without reading every message in the chain.
Ask questions about your inbox in a slide-out chat panel. Get AI-crafted answers with numbered citations linking to specific emails. Click any source to jump straight to it.
Describe what you want to say and AI writes it for you. Adjust tone, expand, shorten — all from the composer with Cmd+J.
Emails automatically labeled as Action Required, FYI, Newsletter, or Custom categories. Zero manual effort.
Dictate emails using Whisper AI running entirely on your device. No cloud, no subscription, no privacy concerns.
Toggle voice readback to hear AI responses spoken aloud as they appear. A pulsing indicator shows when speech is active. Great for multitasking.
Create multiple AI personas with custom instructions, tone, and length preferences. Automatically match profiles to recipient domains.
Native performance on every device. Download, configure your Azure AD app registration, and you’re up and running. No account creation, no subscription — just your tenant.
Join the waitlist and be among the first to experience email at a velocity you didn't think was possible.