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

Castov launched as an open-source developer toolkit that runs 13 utilities locally across a web interface, a CLI invoked via `npx castov`, and a Model Context Protocol server for use inside Cursor or Claude, with the project claiming zero telemetry and no server-side logging of inputs. The toolkit bundles cryptography and JWT inspection via WebCrypto, JSON-to-TypeScript conversion, cron and timezone tools, encrypted URL-hash sharing, RSA-OAEP-encrypted Team Vaults synced through GitHub OAuth, and a Docker image published as castovdev/castov on Docker Hub. Castov also offers a WebRTC/Yjs peer-to-peer node editor for data pipelines and steganographic storage of AES keys in image pixels, positioning the project around keeping developer secrets out of third-party servers.

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.