Castov

Castov

The Open-Source AI Execution Layer & Zero-Telemetry Developer Suite

Deterministic local tooling for Claude Desktop, Cursor, Windsurf, and Local LLMs via the Model Context Protocol (MCP) — backed by a high-performance CLI, Docker image, IDE extension, and 63+ offline-first browser utilities.

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⚡ What is Castov?

Modern AI agents and developer workflows suffer from two critical flaws:

1. Agent Hallucinations on Exact Operations: LLMs frequently blunder arithmetic for CIDR network masks, time zone offsets, epoch milliseconds, and cryptographic key derivations.
2. Data & Secret Leakage: Sending system logs, environment variables, or tokens to third-party cloud APIs presents unacceptable security hazards.

Castov solves both. It acts as an in-situ Execution Layer for developer environments. It provides deterministic, offline, and instant utilities delivered directly to your terminal, editor, Docker containers, and AI agents through the Model Context Protocol (MCP).

Everything runs 100% locally. No external analytics, no telemetry, and zero cloud roundtrips.

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🤖 AI Agent Setup (Model Context Protocol - MCP)

Castov ships with a built-in, production-grade JSON-RPC 2.0 stdio MCP server supporting both Content-Length framed and ndjson stream protocols.

1. Claude Desktop

Add Castov to your claude_desktop_config.json:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• Windows: %APPDATA%\Claude\claude_desktop_config.json
• Linux: ~/.config/Claude/claude_desktop_config.json

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

2. Cursor IDE & Windsurf

Go to Settings → Features → MCP Servers → Add New MCP Server:

• Name: castov
• Type: command
• Command: npx -y castov mcp

Alternatively, add to your project's .cursor/mcp.json:

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

Native Tools Exposed to Agents (10 Tools — All 100% Local & Read-Only)

MCP Tool	Capability	Example Agent Prompt
castov_port	Identifies listening services, protocol mappings, and inspects process collision	"Why is port 3000 busy and what service uses it?"
castov_cidr	Calculates IPv4 subnet masks, wildcard, broadcast, and usable host count	"Calculate usable IP range and subnet mask for 10.240.0.0/22"
castov_detect_id	Decodes embedded creation timestamps from UUIDv7, ULID, ObjectId, Snowflake	"When was this MongoDB ObjectId or Snowflake ID created?"
castov_timestamp	Bidirectional epoch conversion to ISO 8601, UTC, and localized representations	"Convert 1713456789 to human UTC and ISO format"
castov_cron	Parses 5-field cron schedules into plain English and computes next 5 runs	"Explain cron 0 9 * * 1-5 and show the next 5 runs in America/New_York"
castov_timezone	Converts timestamps across IANA time zones with DST transition warnings	"Convert 2026-03-29 14:30 from America/New_York to Europe/Paris"
castov_secret	Generates CSPRNG 256-bit Hex, Base64URL, API keys, and sortable UUIDv7 secrets	"Generate a 256-bit cryptographic secret for AUTH_SECRET and JWT_SECRET"
castov_jwt_decode	Decodes JWT headers, payloads, and exp status offline with zero network calls	"Decode this JWT offline and check if it is expired"
castov_hash	Computes SHA-256/384/512, SHA-1, MD5 digests and Base64/Base64URL encodings	"Compute the SHA-256 hex digest and Base64URL encoding of this webhook payload"
castov_scan_secrets	Audits code snippets, git diffs, or .env blocks for leaked API keys & private keys	"Scan this git diff for any accidentally hardcoded AWS, Stripe, or OpenAI keys"

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📦 Multi-Channel Distribution

Castov is available everywhere modern engineering happens:

1. Terminal CLI (Node.js / npm)

Run instantly without installation:

npx castov --help

Or install globally:

npm install -g castov
castov --help

2. Docker Container (Docker Hub)

Lightweight Alpine Linux container (node:20-alpine) running under a non-root node user:

# Run one-off command
docker run --rm castovdev/castov:latest uuid --v7

# Interactive diagnostic shell
docker run -it --rm castovdev/castov:latest

3. Homebrew Tap (macOS & Linux)

Install natively via Brew:

brew tap castovdev/castov
brew install castov

# Verify installation
castov --version

4. VS Code, Cursor & Windsurf Extensions

Install the official extension directly within your editor:

• VS Code Marketplace: Search Castov or install Castov.castov-vscode
• Open VSX Registry: Available for Cursor, Windsurf, VSCodium: castov/castov-vscode

# Command line installation
code --install-extension Castov.castov-vscode

5. GitHub Action (CI/CD Pipelines)

Automate security scans, secret leakage audits, and environment checks in your GitHub workflows:

- name: Run Castov Secret Scanner
  uses: castovdev/castov-action@v1.0.0
  with:
    command: 'scan .'

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🛠️ CLI Quickstart & Core Commands

castov <command> [options]

🔍 Process & Port Manager (EADDRINUSE Killer)

Inspect what process is occupying a port or kill it cleanly:

# Inspect service and protocol
castov port 3000

# Inspect active process PID and terminate it immediately
castov port 3000 --kill

🔐 Cryptographic Secret Generator

Generate high-entropy keys for .env, NEXTAUTH_SECRET, JWT signing, and API authentication:

castov secret
castov secret --len 64

🌐 Subnet & CIDR Calculator

Calculate network masks, wildcard masks, and usable host ranges with zero external lookups:

castov cidr 192.168.1.0/24
castov cidr 10.0.0.0/16

🛡️ Local Secret Leak Scanner

Recursively scan local directories for committed or uncommitted API tokens (AWS, Stripe, OpenAI, GitHub, Private Keys):

castov scan .

🚑 Crash Log & Terminal Error Healer

Pipe terminal crashes or paste error stack traces for instant, deterministic remediation:

castov fix "Error: listen EADDRINUSE: address already in use :::8080"
npm run build 2>&1 | castov fix

🧠 AI Rules & System Prompt Generator

Bootstrap .cursorrules or CLAUDE.md with hardened engineering practices:

castov rules nextjs --write
castov rules fastapi
castov rules rust

⏱️ Universal ID & Timestamp Detector

Extract metadata and epoch timestamps from any modern distributed identifier:

castov detect 018e3a2b-8a5c-7b00-9821-654321abcdef
castov detect 507f1f77bcf86cd799439011
castov ts 1713456789

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🌐 Complete Suite of 63 Developer Tools

In addition to the CLI and MCP Server, Castov provides 63 client-side web tools accessible at castov.com:

Category	Featured Tools
Security & Privacy	Steganography Env Vault, Client-Side Secret Scanner, Zero-Knowledge Env Vault, Hash Generator (SHA-256/512/MD5), JWT Decoder, Base64 Encoder/Decoder, UUID v4/v7 Generator.
Networking & DevOps	EADDRINUSE Port Inspector, IPv4 CIDR Calculator, Dockerfile Visualizer, P2P Ghost Tunnel, Fetch Mock Generator, API Load Tester, DNS & Header Inspector.
Data & Architecture	JSON to TypeScript Type Generator, 3D JSON Galaxy, Interactive JSON Formatter & Viewer, SQLite In-Browser Fiddle, Line-by-Line Diff Checker, AST Conflict Telepathy.
Frontend & UI	Glassmorphism CSS Studio, App Mockup Generator, High-Resolution Code-to-Image Renderer, Favicon Generator, GitHub Profile README Builder.
Time & Scheduling (25+ Tools)	Unix Timestamp Converter, Epoch Converter, ISO 8601 & RFC 3339 Parser, Timezone Converter & Simulator, Plain-English Cron Generator & Explainer, World Clock, Business Hours Matrix, Milliseconds to Date.

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🔒 Privacy & Zero-Telemetry Guarantee

Engineering tools should never leak your IP, company secrets, or code snippets.

• 0 Analytics or Tracking Cookies: No PostHog, Google Analytics, or third-party telemetry scripts.
• Offline First: All cryptographic operations rely on the browser and runtime's native SubtleCrypto / Web Crypto API.
• Air-Gap Compatible: Both the CLI, Docker image, and web application can run in offline and restricted intranet environments.

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💻 Local Development

Castov is built with Next.js 16 (App Router), TypeScript (Strict), and Tailwind CSS v4.

# 1. Clone repository
git clone https://github.com/castovdev/castov.git
cd castov

# 2. Install dependencies
npm install

# 3. Setup local environment
cp .env.example .env.local

# 4. Start development server
npm run dev

# 5. Build CLI and Web applications
npm run build

To run tests across packages:

npm run test

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📄 License

Castov is open-source software licensed under the MIT License — Copyright © 2026 Abdelmalik Benidir / Castov (castov.com). Free for personal, commercial, and enterprise usage.