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About usepreciso DevTools

Developer tools that run entirely in your browser.

What is this?

usepreciso DevTools is a collection of free utilities that run entirely inside your browser. There is no backend, no database, and no server processing any of the data you enter.

13 tools for developers. All client-side.

🔒 Privacy by default

In the age of AI, everything you paste into a browser tool is potential training data for someone. A JWT you decode, a private document you run a word count on, a JSON payload you format - most tools send that to a server. Some feed it into models.

We built usepreciso so that question never arises. Every calculation, conversion, and transformation happens locally in your browser using JavaScript. Nothing is transmitted. Nothing is stored. Nothing is logged.

✓ No sign-up required✓ No ads✓ No data sent to servers✓ No tracking of tool inputs

The tools

JSON Formatter

Format, validate and minify JSON

JSON Compare

Diff two JSON documents

Base64

Encode and decode Base64

Hash Generator

MD5, SHA-1, SHA-256, SHA-512

JWT Decoder

Inspect JWT tokens without a server

Regex Tester

Test regular expressions live

Cron Builder

Build and explain cron schedules

How it's built

Eight independent Next.js 14 apps share a single npm workspaces monorepo, with a shared@usepreciso/utilspackage for all core logic. Each app is deployed separately to Firebase App Hosting on its own subdomain.

All processing uses native browser APIs - Web Crypto for hashing, Intl for date formatting, Canvas for image processing. No heavy libraries where a native API exists.

Got feedback?

Found a bug, have a feature idea, or just want to say hi? We'd love to hear from you.

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