Level 3Lesson 27⏱️ 90 min

Claude's Ecosystem + Building for Free

A complete map of what Claude can connect to — plus how to ship real applications at zero cost

Part 1: Claude's Built-In Ecosystem

Claude isn't just a chat interface. Through MCPs, Skills, and native tools, it can connect to almost anything. Here is a complete map of what is available — most of which you can enable in minutes.

Official Anthropic MCP Servers

Maintained by Anthropic, installed with a single npx command. Add each to ~/.claude/settings.json:

Filesystem
"filesystem": {
  "command": "npx",
  "args": ["-y", "@modelcontextprotocol/server-filesystem",
           "/Users/you/Documents"]
}

Read, write, and search files. Specify which directories Claude can access.

GitHub
"github": {
  "command": "npx",
  "args": ["-y", "@modelcontextprotocol/server-github"],
  "env": { "GITHUB_PERSONAL_ACCESS_TOKEN": "$GITHUB_TOKEN" }
}

Read repos, create issues/PRs, search code, list commits.

PostgreSQL
"postgres": {
  "command": "npx",
  "args": ["-y", "@modelcontextprotocol/server-postgres",
           "postgresql://user:pass@localhost/mydb"]
}

Query any PostgreSQL database. Works with Supabase, Neon, Railway, etc.

Brave Search
"brave-search": {
  "command": "npx",
  "args": ["-y", "@modelcontextprotocol/server-brave-search"],
  "env": { "BRAVE_API_KEY": "$BRAVE_API_KEY" }
}

Real-time web search. Free tier: 2,000 queries/month.

Notion
"notion": {
  "command": "npx",
  "args": ["-y", "@modelcontextprotocol/server-notion"],
  "env": { "NOTION_API_TOKEN": "$NOTION_TOKEN" }
}

Read and write Notion pages and databases.

Google Maps
"maps": {
  "command": "npx",
  "args": ["-y", "@modelcontextprotocol/server-google-maps"],
  "env": { "GOOGLE_MAPS_API_KEY": "$MAPS_KEY" }
}

Geocoding, directions, place search, distance matrix.

40+ official servers at github.com/modelcontextprotocol/servers — includes Slack, Puppeteer (browser automation), SQLite, Git, memory store, and more.

Community MCP Servers

Desktop Commander — Full filesystem, process management, shell commands, web search.
npx @wonderwhy-er/desktop-commander
Supabase — Query your Supabase project, run migrations, manage auth users.
npx @supabase/mcp-server-supabase --project-ref your-ref
Linear — Create/update issues, manage cycles, query projects.
npx @linear/mcp-server
Stripe — Query payments, customers, subscriptions, issue refunds.
npx stripe-mcp
Vercel — List deployments, check build logs, manage env vars.
npx @vercel/mcp-adapter

Skills: Specialised Expertise Packs

Skills give Claude deep, context-specific expertise for a domain. When you invoke a skill, Claude loads a full set of best practices, templates, and decision frameworks for that task type.

Data Skills — SQL queries, statistical analysis, data visualisation, dashboard building, data exploration
Document Skills — Word (.docx), PDFs, spreadsheets (.xlsx), PowerPoint (.pptx) with full formatting
Sales Skills — Account research, call prep, competitive intelligence, outreach drafting, daily briefing
Engineering Skills — Code review, system design, debugging, testing strategy, incident response
Marketing Skills — Content creation, campaign planning, SEO audit, brand voice, email sequences
Finance Skills — Journal entries, reconciliation, variance analysis, financial statements, SOX testing
Legal Skills — Contract review, NDA triage, compliance checks, canned responses
Bio Research Skills — Single-cell RNA QC, scVI deep learning, Nextflow pipelines, instrument data conversion
Creating your own skills is covered in Lesson 24. Any workflow you repeat more than 3 times is a good skill candidate.

Native Claude Tools (No Setup Needed)

Read / Write / Edit — Direct file access to your workspace.
Bash — Shell commands in an isolated sandbox. Python, Node, npm, pip pre-installed.
Web Search + WebFetch — Search the web and fetch page content.
Computer Use — Control your desktop, click UI, read screens. Unique to Cowork mode.
Gmail / Google Calendar / Drive — Pre-built connectors available via Cowork plugins.

Part 2: Building Real Apps for Free

You now know how to work with Claude at an expert level. The modern free-tier stack lets you turn that into actual products at zero cost — until you have real users.

Vercel — Hosting & Deployment
  • Free: 100GB bandwidth/month, unlimited personal projects
  • Auto-deploy on every Git push, preview URLs for every PR
  • Serverless functions (API routes) and Cron jobs included
  • Best for: Next.js, React, Vue, SvelteKit
Supabase — Database, Auth, Storage
  • Free: 500MB database, 1GB file storage, 50K monthly active users
  • PostgreSQL under the hood — full SQL, Row Level Security
  • Built-in auth (email, OAuth: Google, GitHub, Apple)
  • Real-time subscriptions and pgvector for AI embeddings
Clerk — Authentication (alternative)
  • Free: up to 10,000 monthly active users
  • Beautiful pre-built sign-in/up UI, works with Next.js App Router
  • Social logins, MFA, organisations — all on free tier
Resend — Transactional Email
  • Free: 3,000 emails/month, 100/day
  • React Email for beautiful templates, simple REST API
Cloudflare — DNS, CDN, Workers
  • Free DNS for custom domains, Workers free: 100K requests/day
  • R2 object storage free: 10GB/month
Stripe — Payments
  • No monthly fee — only pay per transaction (2.9% + 30c)
  • Test mode completely free with no limits
  • Subscriptions, one-time payments, invoicing all included

Worked Example: Feedback Collector App in 30 Minutes

A public form where users submit feedback, you view it in a dashboard, and you get an email notification. Cost: $0/month until thousands of users.

Step-by-Step Build with Claude

Step 1 — Scaffold
npx create-next-app@latest feedback-app --typescript --tailwind --app
cd feedback-app
Step 2 — Supabase schema

Go to supabase.com, create a free project, run this SQL in the editor:

create table feedback (
  id uuid primary key default gen_random_uuid(),
  name text, email text,
  message text not null,
  created_at timestamptz default now()
);
alter table feedback enable row level security;
create policy "Anyone can submit" on feedback
  for insert with check (true);
create policy "Auth users can read" on feedback
  for select using (auth.role() = 'authenticated');
Step 3 — Ask Claude to build the form
Build a feedback form at /feedback:
- Fields: name (optional), email (optional), message (required)
- On submit: insert to Supabase table "feedback"
- Use @supabase/supabase-js with env vars:
  NEXT_PUBLIC_SUPABASE_URL and NEXT_PUBLIC_SUPABASE_ANON_KEY
- Show a success message after submit
- Clean Tailwind styling
Step 4 — Ask Claude to build the admin dashboard
Build a protected admin page at /admin:
- Show all feedback entries (newest first) in a table
- Use Supabase server client with env: SUPABASE_SERVICE_ROLE_KEY
- Simple password protection via cookie
- Columns: name, email, message, timestamp
Step 5 — Add email notifications via Resend
Add API route /api/notify:
- Called after each feedback submission
- Sends email via Resend SDK to my@email.com
- Subject: "New feedback from [name or Anonymous]"
- Body: message + sender info
- Env var: RESEND_API_KEY
Step 6 — Deploy to Vercel
vercel --prod
# Or connect your GitHub repo at vercel.com → New Project
# Add env vars in Vercel → Settings → Environment Variables

Live at a .vercel.app URL in under 2 minutes. Add a custom domain with Cloudflare DNS for free.

Total cost: $0/month for up to ~10,000 users, ~500MB of data, and 3,000 emails/month. When you scale: Supabase Pro is $25/month, Vercel Pro is $20/month.

What You Can Build End-to-End

Internal tools — Admin dashboards, data viewers, report generators. Own your data, no SaaS subscription.
AI-powered apps — Connect the Anthropic API (npm install @anthropic-ai/sdk). Claude builds Claude-powered apps for you.
SaaS MVPs — Full auth, payments (Stripe), email, database — the whole stack, free until you have paying users.
Automations — Webhook handlers, scheduled jobs (Vercel Cron), pipelines triggered by Supabase database events.
Lesson 27 Quick Reference
Official MCPs

40+ Anthropic-maintained servers: filesystem, GitHub, PostgreSQL, Brave Search, Notion, Google Maps. Install via npx.

Community MCPs

Desktop Commander, Supabase, Linear, Stripe, Vercel — community-built servers covering major tools.

Skills

Reusable expertise packs for Data, Docs, Sales, Engineering, Marketing, Finance, Legal, Bio Research. Build your own via Lesson 24.

Free stack

Vercel (hosting) + Supabase (DB+auth) + Resend (email) + Stripe (payments) = $0/month until real scale.

Supabase free tier

500MB database, 50K MAU, real-time, Row Level Security, pgvector for AI embeddings. No credit card needed.

Vercel free tier

100GB bandwidth, unlimited projects, auto-deploy from Git, preview URLs, Cron jobs. Best for Next.js.