As developers, how many times a day do we Google "epoch converter", "jwt decode", "cron expression generator", or "base64 decode"?
And how often do we accidentally paste production JWTs, internal JSON structures, or API keys into random websites loaded with third-party trackers?
To solve both the privacy risk and the context-switching tax, we built Castov — a unified, zero-server developer toolkit that runs 100% locally in your browser, your terminal, and Visual Studio Code.
1. In Your Terminal: npx castov
You don't even need to leave your terminal to inspect IDs, parse cron schedules, or handle timezones with Daylight Saving Time (DST) awareness.
Run it immediately with npx or install globally via npm install -g castov:
bash # Auto-detect Unix seconds vs milliseconds npx castov ts 1700000000 # Detect ID format & extract embedded creation timestamp # (Supports MongoDB ObjectId, Snowflake, UUIDv7, ULID) npx castov detect 507f1f77bcf86cd799439011 # Explain cron expressions in plain English + preview next 5 runs npx castov cron "*/15 * * * *" UTC # Generate time-sortable RFC 9562 UUIDv7 npx castov uuid -n 5 --v7 📦 NPM Package: npmjs.com/package/castov 2. In Your Editor: Castov for VS Code Switching from VS Code to Chrome just to convert a timestamp breaks your flow. With the official Castov VS Code Extension : Hover over any 10 or 13-digit number in your code to see UTC, ISO 8601, and Local dates instantly. Decode JWTs offline: Select a token and run Castov: Decode JWT Token to inspect its payload and expiration (exp) in a clean editor tab. Base64 & UUIDs: Encode/decode strings or inject UUIDs directly via Ctrl+Shift+P. 💻 Install on Marketplace: Visual Studio Marketplace - Castov 3. In Your Codebase: castov-sdk Need lightweight utilities in your Node.js, Bun, Deno, or Cloudflare Worker project without pulling in 15 heavy packages? bash npm install castov-sdk typescript import { castov } from "castov-sdk"; const sortableId = castov.uuidv7(); const schedule = castov.cron("0 9 * * 1-5", "America/New_York"); const decoded = castov.jwtDecode(token); 📦 SDK Package: npmjs.com/package/castov-sdk 4. On the Web: castov.com When you do want a visual interface, castov.com offers 60+ blazing-fast utilities with Cmd+K navigation: Unix Timestamp Converter Cron Expression Explainer JSON to TypeScript Interfaces Chrono-DB (In-Browser SQLite + DuckDB Join Engine) Sonic-Gap (Ultrasonic Audio Data Transfer) Everything executes locally on your device. Give it a try and let me know what you think! 
