What's My IP?

Privacy-first IP and browser diagnostics app built with Next.js App Router.

Features

• Deployment-aware IP detection with explicit provenance and trusted Vercel request metadata.
• IPv4/IPv6 breakdown, category detection (public/private/CGNAT/etc).
• Detection confidence and factual request provenance.
• Browser and network signals collected locally with estimate/support-state labels.
• Permission-state, secure-context, and security-header visibility (same-origin).
• Basic/advanced signal toggle with evidence-based diagnostic findings.
• User-triggered WebRTC candidate comparison against the current HTTP address.
• Share, copy, JSON/TXT export, and local history (last 10 checks).
• GET /api/ip endpoint with JSON, report text, or a plain IP response.
• Static security headers and Vercel-native request metadata support.
• SEO-ready metadata with robots.txt, sitemap.xml, Open Graph/Twitter image routes.

Stack

• Next.js 16 + React 19 + TypeScript strict mode
• Tailwind CSS 4 + custom shadcn-style UI primitives
• SWR, Zod, Framer Motion, Lucide, Sonner
• Vitest + Testing Library

Getting Started

npm install
npm run dev

Open http://localhost:3000.

Environment

Copy .env.example values into .env.local for local development.

Required for production SEO correctness:

• NEXT_PUBLIC_APP_URL: your deployed origin (used for canonical/sitemap/robots metadata).

IP and optional location metadata require no provider secret on Vercel. The server uses request metadata exposed by @vercel/functions; local development may not provide the same metadata.

Self-hosted deployments that are strictly behind Cloudflare may set TRUSTED_PROXY_MODE=cloudflare. Do not enable that mode when clients can reach the application directly, because cf-connecting-ip would then be client-controlled.

Scripts

npm run dev
npm run lint
npm run typecheck
npm run test
npm run test:coverage
npm run build
npm run test:smoke
npm run format

SEO

• Canonical, Open Graph, Twitter metadata: src/app/layout.tsx
• Robots: src/app/robots.ts
• Sitemap: src/app/sitemap.ts
• OG image route: src/app/opengraph-image.tsx
• Twitter image route: src/app/twitter-image.tsx

Repository Overview

This repo is also an architecture showcase for a privacy-first diagnostics app.

• Architecture notes and diagrams: docs/project/ARCHITECTURE.md
• API details: docs/project/API.md
• Privacy model: docs/project/PRIVACY.md
• Diagnostic metric semantics: docs/project/DIAGNOSTICS.md
• Contributor workflow: docs/project/CONTRIBUTING.md

Deployment Checklist

1. Set NEXT_PUBLIC_APP_URL to the production origin.
2. Run quality gate: npm run typecheck && npm run lint && npm run test:coverage && npm run build && npm run test:smoke && npm run format.
3. Verify generated SEO assets/routes:
   • /robots.txt
   • /sitemap.xml
   • /opengraph-image
   • /twitter-image
4. Configure abuse protection and request limits in Vercel WAF. The application does not rely on process-local counters, which are not durable across functions or regions.
5. Deploy and re-run Lighthouse (mobile + desktop) on the production URL.
6. Confirm canonical and OG/Twitter previews resolve to the production domain.
7. Verify the production WebRTC test and browser signals in at least one Chromium and one non-Chromium browser; unsupported values must remain labeled as such.

API

See docs/project/API.md.

Privacy

See docs/project/PRIVACY.md.

The application does not load analytics or tracking scripts. Recent-check history is stored only in the current browser's localStorage. Optional location fields come from Vercel request metadata and do not trigger a third-party geolocation lookup.

Contributing

See docs/project/CONTRIBUTING.md.

Changelog

See docs/project/CHANGELOG.md.

Agent Docs

See AGENTS.md and docs/agents/MASTER_INDEX.md.

Authorship

© 2026 Isaac D'Césares

• Website: https://dcesares.dev
• Open Source: https://github.com/idcesares/my-ip
• Vibe coded collaboration: Isaac D'Césares × Codex (GPT-5)

License

MIT