I built a collection of 100% client-side developer tools (JSON, Base64, Crontab). No server uploads, purely secure.

jiang str — Wed, 29 Jul 2026 02:33:28 +0000

As a developer, I use online formatters and encoders every single day. However, most online tool websites are bloated with ads, require logins, or—worst of all—upload our sensitive data (like database JSON configs or API keys) to their servers.

That's why I decided to build a clean, ad-free, and 100% local-run developer toolbox: 6+2 Free Online Tools.

All calculations, parsing, and formatting happen entirely in your local browser. Your data never leaves your computer, which means zero security risks.

Here are a few tools that I use most frequently:

JSON to TypeScript Interface: Generates clean TS interfaces, supports optional properties and exports.

JSON to Go Struct: Converts JSON payloads directly to Go structs with omitempty tags.

Crontab Expression Generator: Generates cron syntax visually, no need to memorize the rules.

JSON Formatter & Validator: Fast, offline-ready formatting with real-time error pointing.

Since it's purely frontend, the loading speed is incredibly fast. You can bookmark it (Ctrl + D) for offline use.

Check it out here: https://www.cqqzx.com/

Any feedback or suggestions for new tools are highly welcome!

DEV Community: jiang str

I built a collection of 100% client-side developer tools (JSON, Base64, Crontab). No server uploads, purely secure.