Free Online Developer Tools
Handy utilities for developers and programmers — format JSON, decode tokens, generate UUIDs, and more. All tools run in your browser, no install needed.
All Developer Tools
JSON Formatter
Prettify, validate, and minify JSON data instantly. Highlights syntax errors and formats nested structures cleanly.
Use tool →JWT Decoder
Decode and inspect JWT tokens — view header, payload, and signature without verifying the secret.
Use tool →Base64 Encoder
Encode plain text or decode Base64 strings instantly. Useful for auth headers, data URIs, and API payloads.
Use tool →Password Generator
Generate strong, random passwords with custom length, symbols, numbers, and case options.
Use tool →Cron Generator
Build and validate cron expressions with a visual editor. See a human-readable schedule summary instantly.
Use tool →UUID Generator
Generate v4 UUIDs in bulk for use in databases, APIs, and distributed systems. Copy with one click.
Use tool →URL Encoder
Encode or decode URL components and query strings. Handles special characters for safe use in HTTP requests.
Use tool →Timestamp Converter
Convert Unix timestamps to human-readable dates and back. Supports seconds, milliseconds, and multiple timezones.
Use tool →Why Use Attachad Developer Tools?
Developers constantly context-switch between tasks — debugging an API response, decoding an auth token, building a cron schedule. Keeping browser tabs open for a dozen scattered utilities wastes time. Attachad brings the most-used developer tools into one place, all free and instantly accessible.
Need to quickly format and validate a JSON response from an API? Or inspect a JWT token to debug an authentication issue? Maybe you need to generate a batch of UUIDs for a database migration. Each tool is purpose-built to be fast and distraction-free.
Crucially, sensitive data like tokens and passwords never leave your device — most tools process everything client-side in JavaScript, so you can confidently use them with real credentials during development.
Most Common Developer Tool Use Cases
JSON Formatter — Paste a minified API response and instantly see a readable, indented structure. The formatter also validates the JSON and highlights syntax errors, making it faster than scanning raw output in a terminal.
JWT Decoder — Decode a JSON Web Token to inspect its header algorithm and payload claims without needing the signing secret. Useful when debugging OAuth flows, checking token expiry (exp), or verifying claim values.
Base64 Encoder / Decoder — Quickly encode strings for use in HTTP Basic Auth headers or data URIs, or decode Base64-encoded API responses and webhook payloads. Our Base64 tool handles both directions in one view.
Cron Generator — Writing cron expressions from memory is error-prone. The visual cron generator lets you configure the schedule with dropdowns and shows a plain-English summary like "every Monday at 9:00 AM" before you copy the expression into your scheduler.
Timestamp Converter — Unix timestamps show up everywhere in logs, databases, and API responses. The timestamp converter translates between Unix time (seconds or milliseconds) and human-readable dates across multiple timezones instantly.
How to Use These Tools
- 1Pick your tool: Choose from the cards above based on what you need — each card shows a short description of the tool's purpose.
- 2Paste or type your input: Enter your data directly into the input field. No file uploads needed for most tools.
- 3Get your result instantly: Output is generated in real time as you type, or with a single button click.
- 4Copy and move on: Use the one-click copy button to grab the output and paste it wherever you need it.
Frequently Asked Questions
Are these developer tools free to use?
Yes. Every tool on Attachad is 100% free with no account, no subscription, and no usage limits. Just open and use.
Is my data sent to a server?
Most tools run entirely in your browser using JavaScript — your data never leaves your device. For any server-side processing, inputs are not logged or stored.
Can I use these tools on mobile?
Yes. All tools are fully responsive and work on smartphones and tablets as well as desktop browsers.
Do the tools work offline?
Once a page is loaded, many tools (like JSON Formatter and Base64 Encoder) will continue to work without an active internet connection as processing happens client-side.