Is there a free way to build real apps with Claude?

Yes, end to end. A free Claude account can add one custom connector, and a free Fine Structure account builds and publishes a working app on a free subdomain, no credit card. Paid plans add custom domains, more builds and higher limits, but the free path produces a live, shareable product.

What stays free is deliberate: connecting, building a first app, publishing it at yourname.finestructure.ai, editing it, and rolling back changes. The paid line sits at your own domain, volume, and the heavier AI features, detailed on the pricing page.

What the connector actually does

Generates a complete application from a prompt: React pages, a managed database, authentication, styling.
Publishes to a live URL on a free subdomain, and connects a custom domain with automatic TLS on paid plans.
Edits existing apps: reads files, patches them, validates, republishes. Every change keeps a restorable saved version.
Creates database schemas and records, queries them back, and reports on them.
Reads traffic analytics and runtime errors for published apps, then fixes what it finds.
Creates standing AI agents that run on a schedule and can message their verified owner on WhatsApp and by email.
82 tools over the OAuth surface and 13 starter prompts, documented at finestructure.ai/api/mcp/docs.

Connecting takes about two minutes

Open claude.ai and sign in. A free Claude account is enough; free accounts can add one custom connector.
Go to Settings, then Connectors, choose Browse connectors, and search for Fine Structure. Click Connect.
Sign in with a Fine Structure account (the free tier is enough, no credit card) and approve.
Back in the chat, ask for what you want built. The result is published at a public link.

In Claude Code: claude mcp add --transport http finestructure https://finestructure.ai/api/mcp, then run /mcp to authenticate. The full guide covers the desktop app and every other client.

Questions people ask

Does this work on a free Claude plan?

Yes. Anthropic documents custom remote MCP connectors on Free, Pro, Max, Team and Enterprise, with free accounts limited to one custom connector. A free Fine Structure account is enough on the other side, and no credit card is required.

Is the free app watermarked or crippled?

It is a real application with a real database at a real public address. Limits are on volume and premium features, not on whether the product works.

Do I need an API key?

No. The connector uses OAuth: you sign in on a Fine Structure page and approve. No key, no client ID, no secret to paste anywhere.

Where this is listed

Fine Structure is a Community connector in Anthropic's connector directory (listed, not verified or endorsed), and the same server is recorded in the official MCP registry as ai.finestructure/fine-structure, on Smithery and on Glama. The endpoint answers publicly at /api/mcp/manifest, so any claim on this page can be checked against the live tool list.