# Show HN: Castov – Open-source dev tools and AI secret shield with zero telemetry

> Source: <https://castov.com>
> Published: 2026-10-31 19:30:14+00:00

# The Complete Developer Toolkit 

Web + CLI + AI (MCP)

All your mission-critical utilities executed locally in your browser, terminal, and AI agents. Zero server tracking, sub-millisecond transforms, and seamless multi-stage pipelines.

`Ctrl + K`

`npx castov`` castov mcp`
Simulates the full `castov-cli` suite locally via WebCrypto and instant transforms.

Click any quick-run chip above or type `help` to see commands.

[CLI Docs](https://castov.com/cli)

## Why Developers Choose Castov

Five architectural decisions that make Castov the preferred toolkit for modern software teams.

### Zero-Data Logging

WebCrypto
100% of cryptography, JWT inspection, JSON formatting, and timestamp parsing executes in local browser memory. Not a single keystroke is sent to external servers.

### Tool Pipelines ("Pipe to...")

Chaining
Pass outputs seamlessly across utilities in one click: JSON directly to TypeScript interfaces, Cron schedules into world timezones, and diffs to schema generators without clipboard juggling.

### Unified Ecosystem

Web • CLI • MCP
The exact same 13 utilities work on the Web, in your local terminal via `castov`, and inside Cursor or Claude via our Grade-A certified Model Context Protocol server.

### Encrypted URL Shares

Zero-Server
Share inputs, diffs, and settings with teammates instantly. Payloads are compressed into the URL hash fragment (`#`) so servers never see what you shared.

### E2EE Cloud Sync & Team Vaults

GitHub OAuth
Zero-friction leverage unlocked on registration

[Connect Workspace](https://castov.com/account)

Connect your GitHub account to sync pinned utilities, presets, and dev preferences across all your machines. Collaborate with teammates using RSA-OAEP encrypted Team Vaults to share `.env` files without cleartext exposure in chat channels.

## Deploy Castov Everywhere You Build

Whether inside your local terminal, Docker containers, AI editors, or automated CI/CD pipelines — Castov provides the instant execution layer for developers and MCP AI agents.

### Docker Hub

Run Castov CLI and MCP runtime in an isolated, non-root Alpine container with zero host dependencies.

[Official Registry](https://hub.docker.com/r/castovdev/castov)

```
docker run --rm -it castovdev/castov:latest --help
```

## Advanced Capabilities

We didn't just build formatters. We built the architecture required by modern engineering teams.

### P2P Multiplayer Canvas

A visual node-editor for building data pipelines. Connects peers in real-time using WebRTC and CRDTs (Yjs) with direct peer-to-peer data channels coordinated through public signaling servers (which may receive connection metadata). Workflow graphs, node configurations, and payload data are never stored on Castov servers.

### Steganography Environment Vaults

End-to-end encrypted environment variables. We hide your secure AES keys inside standard image pixels (Steganography) for invisible sharing, entirely in your browser.

Test your frontend without a backend. Our Local API Mocker runs entirely in your browser's Service Worker to simulate payloads globally.

## Explore Our Toolkit

From time manipulation to cryptography, everything is beautifully structured and instantly accessible.

## Timestamp

7 tools

Convert, validate, compare and work with Unix timestamps.

## Date & Duration

5 tools

Calculate differences, durations, and add or subtract time from a date.

## Time Zones

6 tools

Convert, compare and browse time across the world's time zones.

## Developer

33 tools

ISO 8601, RFC 3339, cron and other formats developers work with daily.

## Labs

Experimental tools
Experimental tools: WebRTC P2P mesh, steganography, AST parsing, and in-browser WebGL computing.

## Frequently Asked Questions

Everything you need to know about Castov.

## Frequently Asked Questions

## Is Castov really free?

## Is my data sent to a server?

## What is a Unix timestamp?

## Should I use seconds or milliseconds?

## Which time zones are supported?

## Ready to supercharge your workflow?

Free browser-based developer tools. Some collaboration, cloud, and external API features may require an account or additional configuration.