BrightMail AI

About

BrightMail AI surfaces what matters in your email — dates, dollar amounts, deadlines, and action items, and highlights them in your Gmail draft before you send. All analysis happens on-device using Chrome's built-in Gemini Nano model. Nothing leaves your browser.

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WHAT IT DOES
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• Reads your draft when you click "Highlight" in the Gmail compose toolbar.
• Identifies key phrases in seconds using a hybrid of fast regex extraction and Gemini Nano.
• Shows you a preview popover so you can approve or skip each phrase before anything is changed.
• Wraps approved phrases in a styled highlight you can fully customize.
• Plays nicely with Gmail dark mode, signatures, and quoted replies (those sections are excluded from analysis).

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WHY ON-DEVICE
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Your draft never goes to OpenAI, Anthropic, Google's servers, or anywhere else. The Gemini Nano model runs locally inside Chrome. There is no network call for AI analysis. There is no telemetry. Your settings live in chrome.storage and never sync to a third party.

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HIGHLIGHT STYLES
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Three presets in the preview popover:
  • Subtle  — bold only, no fill
  • Standard — soft yellow background + bold (default)
  • Bold — yellow background + bold + underline

Or open Settings to fine-tune background colour, text colour, and modifiers for both light and dark Gmail themes.

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KEYBOARD
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  ⌘⇧H  (Mac) / Ctrl+Shift+H (Win/Linux) — run highlight on the active compose
  Tab / Esc inside the preview popover for keyboard navigation
  Space — toggle a phrase
  Enter — apply

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REQUIREMENTS
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  • Chrome 128+ on a desktop / laptop with at least 4GB free disk for the on-device model
  • Enable two flags once at chrome://flags
      #optimization-guide-on-device-model  →  Enabled BypassPerfRequirements
      #prompt-api-for-gemini-nano          →  Enabled
  • Confirm the model has downloaded at chrome://components → "Optimization Guide On Device Model" shows a non-zero version

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KNOWN LIMITATIONS
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  • Applying highlights replaces the compose body, which clears Gmail's native Cmd+Z stack for that step. Use the "Clear highlights" action instead of undo.
  • The first run after enabling the flag downloads ~4GB of model weights — this is one-time.
  • Phrases that span across multiple HTML elements (e.g. a date split across two lines mid-format) are skipped in v1.

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PRIVACY & PERMISSIONS
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We request only the permissions strictly required to function. See the privacy policy for the full breakdown.

  • storage     — save your highlight colour, style preset, and onboarding flag
  • activeTab   — read the compose body when you click the Highlight button
  • commands    — register the keyboard shortcut
  • scripting   — inject the AI bridge that talks to Gemini Nano
  • host: https://mail.google.com/* — only runs on Gmail

No analytics. No ads. No background tracking. No external API calls.

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SUPPORT
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Questions, bugs, feature requests: https://x.com/LBWalton