I built Castov – 900+ Offline-First Developer Tools, Terminal Error Healer & VS Code Extension (Zero Telemetry)

Description and use

A developer built Castov, a 100% client‑side suite of 900+ offline‑first tools, including terminal error healing, zero‑knowledge .env encryption, and a VS Code extension, all without telemetry.

Problem

Developers were forced to paste sensitive JWT tokens, .env secrets, and production JSON payloads into slow, ad‑heavy websites that logged everything on their backend.

Outcome

Developers can diagnose terminal errors, encrypt secrets locally, fetch AI rules, lookup ports, and enhance VS Code without exposing data to external servers.

Workflow

• 1. Install Castov via npm: npx castov fix "error message" to diagnose terminal errors instantly.
• 2. Encrypt .env variables in the browser with AES‑GCM 256‑bit and store the key in the URL hash: visit https://www.castov.com/env‑vault.
• 3. Fetch AI‑generated cursor rules into a project: curl -sL https://www.castov.com/api/rules/nextjs-15 > .cursorrules.
• 4. Look up network ports and CIDR subnets with instant copy‑paste kill commands or Docker rules via https://www.castov.com/ports.
• 5. Install the VS Code extension to hover over Unix timestamps, generate UUID v7, and decode JWTs directly in the editor: code --install-extension castov.castov-vscode.
• 6. Explore the full directory of 900+ tools at https://www.castov.com/directory.

Evidence

I got tired of pasting sensitive JWT tokens, .env secrets, and production JSON payloads into slow, ad‑heavy websites that log everything on their backend.

Source

So I built Castov — a 100% client‑side, zero‑telemetry developer utility suite.

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Terminal Error Healer (npx castov fix) Pipe any failed build or error message directly in your terminal to get an instant root‑cause diagnosis

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Zero‑Knowledge .env Secret Sharing: Encrypts your .env variables in the browser using AES‑GCM 256‑bit and stores the decryption key in the URL #hash (so the key never touches the server)

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Official VS Code Extension: Hover over any Unix timestamp to see UTC/Local time, generate UUID v7, and decode JWTs inside your editor

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