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Mikey Bailey
Mikey Bailey

Posted on • Originally published at nordicnode.github.io

5 Free Developer Tools That Run Entirely in Your Browser

If you have ever used an online tool that asked you to create an account, verified your email, and then tried to upsell you on a paid plan before letting you format some JSON — you know the pain.

I built DevToolKit as a free, no-signup alternative. Every tool runs 100% client-side in your browser. No data leaves your machine. No cookies. No tracking.

Here are 5 tools from DevToolKit that I use almost daily:

1. Regex Tester

Write a regex pattern, type test strings, and see matches highlighted in real time. Supports flags, capture groups, and a cheat sheet for common patterns.

Try the Regex Tester →

2. JSON Formatter

Paste minified JSON and get a clean, indented view. Detects syntax errors instantly. Also validates structure — unmatched brackets, trailing commas, and more.

Try the JSON Formatter →

3. JWT Decoder

Paste any JWT token and instantly see the header, payload, and signature details. No server calls — decode happens in your browser using base64 parsing.

Try the JWT Decoder →

4. Hash Calculator

Compute MD5, SHA-1, SHA-256, and SHA-512 hashes from any text input. Uses the Web Crypto API — no server round-trips.

Try the Hash Calculator →

5. Base64 Encoder/Decoder

Encode text to Base64 or decode Base64 back to text. Handles UTF-8 properly. Useful for debugging API responses, email attachments, and data URLs.

Try the Base64 Tool →


More Tools

DevToolKit has 15+ free tools including a UUID generator, URL encoder, color converter, HTML entity encoder, timestamp converter, cron parser, diff checker, and more. All at:

nordicnode.github.io/devtoolkit

No signup. No tracking. Just tools.

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