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© 2026 ConverterHub. All tools are free and client-side.Made for developers who ship.

Free Online Developer Tools — in Your Browser

Format JSON, decode JWTs, encode Base64, convert Unix timestamps — paste and convert right here. No sign-up, no tracking, no server calls.

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All tools

9 tools · 100% free

Formatters

JSON Formatter & Validator
Beautify minified JSON, validate syntax, and debug errors instantly. Free online JSON parser that runs 100% in your browser for privacy.

Encoders

Base64 Encoder / Decoder
Convert text to Base64 or decode Base64 strings back to text. fast, client-side, and handles UTF-8 characters correctly.
URL Encoder / Decoder
Escape special characters in URLs (percent-encoding) or decode them back. Essential for debugging query parameters and API strings.

Converters

Timestamp to Date Converter
Free online tool to convert Unix timestamps (seconds & milliseconds) to human-readable dates. RFC 2822 & ISO 8601 formatting. Client-side only.
JSON to CSV Converter
Convert nested JSON arrays to CSV format for Excel or Google Sheets. flattens objects and handles headers automatically.

Dev Utilities

JWT Decoder (Debug Only)
Decode JSON Web Tokens (JWT) to inspect headers and payloads. Client-side only for security - no secret keys required.
UUID Generator (v4)
Generate secure, random UUIDs (Universally Unique Identifiers) version 4 locally in your browser. Bulk generation supported.
HTML Entity Escape / Unescape
Escape special characters to HTML entities (e.g. < to &lt;) or unescape them back. Prevent XSS and format code for display.

Text

Word & Character Counter
Count words, characters, sentences, and paragraphs in real-time. Includes reading time estimation. Perfect for essays, tweets, and SEO.

From the blog

Practical notes on the tools developers actually use.

All posts →
Aug 4, 2026 · 5 min read
HTML escape and unescape: stopping XSS in modern web apps
I've seen my share of security vulnerabilities in web applications, but one that still manages to slip through the cracks is cross-site scripting, or XSS. It happens when an attack
Aug 3, 2026 · 6 min read
Base64 encoding explained for web developers
When working with web applications, I often encounter situations where I need to transfer binary data, such as images, over text-based protocols like HTTP. One common approach to s
Aug 2, 2026 · 6 min read
Password generation: the honest guide for developers
I still remember the first time I had to implement a password generator for a web application. The requirements were simple: generate a random password of a given length. However,

Frequently asked questions

Are these developer tools really free?+

Yes. Every tool on ConverterHub is free with no sign-up, no paywall, and no usage limits.

Is my data sent to a server?+

No. All conversions run entirely in your browser. Nothing you paste is transmitted to our servers.

Do the tools work offline?+

Once a tool page has loaded it typically keeps working without a network connection, because all processing happens in the browser.

Which tool should I use to decode a JWT?+

Use the JWT Decoder. It splits the token into header, payload and signature and shows expiry in a human-readable format. It never asks for your secret.