HTML Cloud

HTML Cloud

Share an HTML file. Keep the key.

Zero-knowledge, end-to-end encrypted HTML file sharing.

HTML Cloud · npm · Security · CLI · MCP

Your browser encrypts the file with AES-256-GCM before anything is uploaded. The decryption key lives after the # in the share URL — browsers never send that part to the server. We store only ciphertext.

How it works

1. Drop an HTML file on the homepage
2. Your browser generates two random keys: a view key (AES-256-GCM) and an edit key
3. The file is encrypted in-browser and uploaded as ciphertext
4. You get two links:
   • Share link /v/{id}#viewKey — give this to anyone you want to read the file
   • Edit link /e/{id}#editKey — keep this private; it lets you replace the file, change its expiry, or delete it without changing the share link
5. Files self-destruct after the chosen expiry (7 days, 30 days, or never — 30 days by default)

The server stores:

• The encrypted blob
• The view key encrypted with the edit key (so the edit page can re-encrypt without exposing the view key)
• SHA-256(editKey) for authorization — never the plaintext keys

Security properties

• Zero-knowledge uploads — the server cannot read any uploaded content
• Key-in-fragment — browsers strip the URL fragment before sending HTTP requests; the key never reaches the server
• Edit authorization — only SHA-256(editKey) is stored; the raw edit_key is verified on every write request (replace, expiry, settings, delete)
• Expiry enforcement — expired documents are invisible to every route and hard-deleted daily by model:prune
• 10 MB upload limit enforced server-side
• No accounts — the API is stateless; every state-mutating request is authorized by the edit key, and uploads are rate-limited

See html.cloud/security for the full write-up.

CLI

Share a file from the terminal — encrypted locally, same crypto module as the browser:

npx html-cloud ./file.html

Or pipe straight from a generator:

my-report-tool | npx html-cloud -

The package lives in cli/ and on npm. See html.cloud/cli for usage and options.

MCP server

Let Claude (or any MCP client) share HTML for you. The server is published as html-cloud-mcp and lives in mcp/:

{
  "mcpServers": {
    "html-cloud": {
      "command": "npx",
      "args": ["-y", "html-cloud-mcp"]
    }
  }
}

See html.cloud/mcp for setup instructions.

Agent skill

plugin/skills/html-cloud/SKILL.md tells an agent when to share through html.cloud and how — with the MCP server or, without it, the CLI — including updating a page at the same link instead of sharing a new copy. Copy the plugin/skills/html-cloud/ folder into your agent's skills directory (for Claude Code, ~/.claude/skills/).

Stack

• Laravel 13 (PHP 8.4+)
• SQLite (swap to MySQL/Postgres via .env for production)
• Vite 8 (CSS and JS build pipeline)
• Web Crypto API (all crypto is browser-native; no external crypto libraries)

Setup

cp .env.example .env
php artisan key:generate
php artisan migrate
npm install && npm run build
php artisan serve

Run the test suite with:

php artisan test

For production, add a cron entry to run the scheduler:

* * * * * cd /path/to/html.cloud && php artisan schedule:run >> /dev/null 2>&1

Self-hosting

Clone, configure .env (APP_URL, DB_* if using MySQL/Postgres), run behind nginx or Caddy. Everything, including the encrypted blobs, lives in the database — back that up and you have the whole state.

License

MIT