AI Productivity
Email Responder
A Chrome extension that learns your writing style from sent emails and auto-generates personalized Gmail draft replies. Supports 8 different AI providers, knowledge base uploads, and multi-account switching.
Type
Chrome Extension
Platform
Gmail (MV3)
AI Providers
8 supported
Auto-reply
Every 10 min
Why I built this
I was spending too much time writing repetitive email replies that all followed the same pattern — my pattern. I wanted a tool that could learn my actual writing style from my sent emails, then draft replies that sound like me. Not generic AI text, but replies with my greeting style, my vocabulary, and my level of formality.
How it works
Sign in and connect your Gmail
Learn your writing style
Auto-draft replies in your tone
Add context with a knowledge base
Key features
Tone learning
Analyzes sent emails to extract formality, greetings, vocabulary, humor, and characteristic phrases
8 AI providers
Claude, OpenAI, Gemini, Grok, DeepSeek, Qwen, Kimi, GLM — switch anytime
Knowledge base
Upload company docs, product info, or FAQs as .md/.txt/.zip to improve reply quality
Multi-account
Switch between Gmail accounts with independent settings and tone profiles for each
Smart filtering
Skips newsletters, automated emails, non-English, calendar invites, and thank-you messages
Activity log
Tracks last 50 actions — which emails were drafted, which were skipped, and why
Tech stack
Extension
AI Providers
Also supports OpenAI, Grok, DeepSeek, Qwen, Kimi, and GLM
APIs and Storage
Chrome Identity (OAuth2), Chrome Storage, Chrome Alarms
Architecture
Manifest V3 Chrome extension with service worker background script. No build step — vanilla JavaScript with ES modules.
Unified callLLM() abstraction handles 8 different AI API formats (Anthropic, OpenAI-compatible, Gemini's schema). Includes 429 rate-limit retry logic.
All data stays local — API keys, tone profiles, and processed email IDs stored in chrome.storage.local. Nothing sent to any server except the chosen AI provider.
Multi-layer filtering: sender patterns (noreply, newsletters), subject patterns (OOO, verify), language detection (English-only via word frequency), and AI-powered triage (newsletter vs. actionable).
Chrome Alarms schedule auto-reply every 10 minutes and tone profile refresh weekly. Rate-limited at 15-30s between emails per batch.
Interesting details
- -Custom English language detection using word frequency analysis — rejects emails with too many accented characters or insufficient common English words.
- -Lightweight ZIP parser for knowledge base uploads using DataView — extracts .md and .txt files without any external library.
- -Thread-aware replies: checks full conversation context, skips if already replied, groups by thread ID to avoid duplicate drafts.
- -Email signature stripping removes patterns like "Sent from my iPhone" and "Get Outlook for iOS" before tone analysis to keep the profile clean.
What I learned
- -Chrome Manifest V3 service workers have no persistent state — all in-memory data disappears on sleep. Design around chrome.storage from the start.
- -The hardest part of an auto-reply tool isn't generating replies — it's deciding which emails NOT to reply to.
- -Supporting multiple LLM providers taught me how different their API formats really are, even when they claim OpenAI compatibility.