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
</>

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.