Free Online Developer Tools — JSON Formatter, Base64, JWT Decoder & More

20 free online developer tools for JSON formatting, Base64 encoding, JWT decoding, UUID generation, QR code creation, timestamp conversion, and text processing. 100% client-side, no data leaves your device.

All Tools

20 tools
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JSON Formatter

Format, validate, minify and compare JSON data

Data Format
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JSON to Table

Convert JSON arrays to interactive HTML tables

Data Format
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JSON to XML

Convert JSON to XML and vice versa

Data Format
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JSON to YAML

Convert JSON to YAML and vice versa

Data Format
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XML Formatter

Format, validate, and minify XML data with syntax highlighting

Data Format
[]

Base64 Encoder

Base64 encode and decode, with UTF-8 support

Encoding
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Image to Base64

Convert images to Base64 strings or decode Base64 back to images

Encoding
#

Hash Calculator

Calculate MD5, SHA-1, SHA-256, SHA-512 hashes via Web Crypto

Encoding

URL Encoder

Safely encode or decode URL components with %20 or + space encoding

Encoding
0x

Hex Converter

Convert text to hexadecimal or hex to text with UTF-8 support

Encoding
🔐

JWT Decoder

Decode JWT tokens instantly, view header, payload and signature

Encoding
Aa

Word Counter

Count characters, words, sentences, and paragraphs in real-time

Text Tools
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Regex Tester

Test regular expressions in real-time with flag support

Text Tools

Timestamp Converter

Convert Unix timestamps to readable dates

Time Tools
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UUID Generator

Generate random UUID v4 identifiers with format options (case, hyphens, wrap)

Utilities
🔒

AES Encryptor

Encrypt and decrypt text using AES-128/192/256 with CBC or ECB mode

Security
🔐

3DES Encryptor / Decryptor

Encrypt and decrypt text using 3DES with ECB, CBC, CFB, OFB modes

Security
🔑

RSA Encryptor

Generate RSA key pairs and encrypt/decrypt with public/private keys

Security

QR Code Generator

Generate and decode QR codes. Create QR codes from URLs or text, or decode QR codes from images.

Utilities
📄

Image to PDF

Convert images to PDF documents, support batch merge and custom page size

Utilities

About Online ToolZen

🔒

100% Client-Side

All tools run entirely in your browser. No data is uploaded to any server. Your inputs stay private and secure.

Lightning Fast

No waiting for server responses. Every operation completes in milliseconds because it happens locally on your device.

📱

Works Everywhere

Fully responsive design that works on desktop, tablet, and mobile. Install as a PWA for an app-like experience.

💰

Forever Free

No subscriptions, no premium tiers, no ads cluttering your workspace. Just clean, fast tools that get the job done.

Need a tool you don't see? Let us know — we're always adding new utilities based on user feedback.