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!
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