Projects / Chrome extension

WhatsApp Smart.

Prototype, never launched

I wanted to schedule a birthday message for midnight, and WhatsApp couldn't. So I built a Chrome extension that adds scheduling, AI replies, tone adjustment and group summaries. Messages stay in the browser unless you send one to the AI.

11features built
3codebases
14tests
~16,000lines of TypeScript
The problemThe missing layer

WhatsApp's own scheduling, added in early 2026, is single-message only with no recurring option. Busy group chats pile up unread, and nothing helps with replies. Every third-party tool in this space targets businesses running customer support through the WhatsApp Business API. Personal users got left behind.

The extension
WhatsApp Smart extension panel inside WhatsApp Web
Extension UI
WhatsApp Smart scheduling interface mockup
Scheduling flow
How it worksThree layers, local first

You open WhatsApp Web and the extension is already there: a small toolbar next to the compose box with AI suggestions, a tone adjuster and a schedule button. Message access comes from an open-source WhatsApp Web API library, not brittle DOM scraping. No server required for core features. No sign-up.

  • In the pageA content script spots WhatsApp Web with a MutationObserver and mounts a React 19 UI of 54 components in shadow DOM, talking to the page through a postMessage bridge.
  • In the extensionA 1,400-line background worker runs the scheduler and send queue on Chrome Alarms, with retries and 3 to 10 second gaps between batch sends. All user data stays in local storage.
  • Outside, optionalClaude, Haiku for speed and Sonnet for quality, with your own key or through a small Hono proxy. Upstash Redis keeps server-side schedules and push subscriptions for when Chrome is closed.
What it doesEleven features
  • Smart schedulingOne-off or recurring messages, per-contact office hours so nothing fires at 3am, staggered batch sending.
  • AI reply suggestionsReads the chat context and suggests three replies instantly. Learns your emoji habits and tone.
  • Tone adjusterDraft quickly, then rewrite as formal, casual or professional with one click.
  • Group chat summary30+ unread messages become structured bullets: decisions, assignees, deadlines.
  • Undo sendA five-second countdown intercepts every message before it hits WhatsApp's servers.
  • Follow-up remindersFlag messages to bounce back later; keyword alerts for terms like "urgent" or "deadline".
  • Privacy firstAll data in local Chrome storage. No sign-up. Messages stay in the browser; only text you send to the AI leaves it, and those prompts are not stored.
Undo send, working replicaPrototype
Are we still on for tonight?
5s Yes, see you there. I'll bring the contracts.
Press send, then try to take it back.
What went wrongBuilt on someone else's page

The whole extension sits on top of WhatsApp Web's own HTML. It reads that page and drives it, and WhatsApp can change it whenever they like without telling anyone. One update on their side could break sending overnight. I can't unit-test my way out of it either, because the code under test depends on markup I don't own. The spec logs it as known issue one.

Stack
React 19UI and state, 54 components
TypeScript 5.9~16,000 lines, strict
WXTExtension framework, Manifest V3
Tailwind v4 + RadixStyling and accessible primitives
Claude APIHaiku and Sonnet, BYOK or proxy
Chrome AlarmsBackground scheduling
WPP / wa-jsWhatsApp Web access, no DOM scraping
Hono + Upstash RedisPush and AI proxy, server state
Next.js 15Landing page, Vercel

It never shipped. It stays on the list for the engineering.

Other projects
01 OpsPilot The AI that answers my messages: 6,124+ documents, live finance data, one-click approval. Production
02 Trading Bot Four AI agents that veto my trades. 115+ sessions, zero impulsive trades let through. Paper trading
03 Uni-Nation Digital Website, inventory PWA and Hindi voice stock entry for the family fabric business. Being repaired
05 SCS Cockpit The study engine I built for my own CIMA Strategic Case Study. I passed. Retired, job done