Fast, Free
Developer Tools
Fast, free browser-based utilities for everyday developer tasks: JSON formatting and conversion, JWT decoding, Base64 conversion, UUID generation, and more. Everything runs locally in your browser — your data never leaves your device.
Developer Tools
View allJSON Formatter
Format, minify, and beautify JSON data. Powered by Monaco Editor for a VS Code-like experience.
JSON Validator
Validate JSON syntax and catch errors — trailing commas, missing quotes, and unescaped characters.
JSON ↔ YAML Converter
Convert JSON to YAML or YAML to JSON instantly in your browser.
JSON ↔ XML Converter
Convert JSON to XML or XML to JSON with custom attribute support.
JSON ↔ CSV Converter
Convert JSON to CSV or CSV to JSON with flexible delimiter controls.
JWT Decoder
Decode JWT headers and payloads locally. Your sensitive tokens never leave your browser.
Base64 Converter
Encode text or images to Base64, or decode Base64 strings back to plain text and Data URLs.
UUID Generator
Generate cryptographically secure UUID v4 identifiers in bulk using the Web Crypto API.
Timestamp Converter
Convert Unix epoch timestamps to human-readable dates, or pick a date to get its timestamp.
Regex Tester
Test regular expressions with live match highlighting and replace testing.
URL Encoder / Decoder
Encode URLs for safe transmission or decode percent-encoded strings instantly.
Hash Generator
Compute SHA-256, SHA-512, MD5, and SHA-1 cryptographic checksums in real-time.
Why DevToolkit?
Private by Default
All processing happens in your browser using native JavaScript APIs. We never receive, log, or store your data.
Instant Results
No API calls, no round-trips. Every tool runs locally, so results appear instantly as you type.
No Account Required
All tools are completely free with no sign-up, no paywalls, and no subscription.
Built for real debugging workflows
DevToolkit is designed for the small checks that happen between writing code and shipping it. A developer can validate a payload, inspect a token, compare a serialized format, generate a test identifier, or investigate a timestamp without creating an account or moving the working data to a service.
Understand the output
Guides explain the format, not just the button that produces a result.
Know the boundary
Security-sensitive tools identify what they inspect and what they cannot verify.
Keep control
Tool inputs are processed locally; third-party website services are explained in our privacy policy.
Developer Guides
Practical technical guides that explain the concepts behind the tools — from JSON syntax to JWT security.
Sep 8, 2026
What is JSON? A Complete Developer's Guide
Learn JSON syntax, all six data types, the difference from JavaScript objects, and how to fix the most common JSON errors.
Read guide →Sep 17, 2026
What is a JWT? JSON Web Tokens Explained
Understand the three-part JWT structure, what decoding vs verifying means, and why you should never trust a token without verification.
Read guide →Sep 15, 2026
What is UUID? Complete Guide for Developers
UUID versions, use cases, database vs auto-increment IDs, and why UUID v4 is the de-facto standard for most applications.
Read guide →Sep 18, 2026
Is Base64 Encoding the Same as Encryption?
Base64 is not encryption. Learn what it actually does, when to use it, and why storing passwords as Base64 is a critical security mistake.
Read guide →Sep 28, 2026
JSON vs XML: Which Data Format Should You Choose?
Compare JSON and XML syntax, performance, validation, and practical use cases for modern applications.
Read guide →Oct 17, 2026
JSON Beautifier Online: Format, Minify, and Inspect JSON
Learn when to beautify, format, minify, or validate JSON before using it in an API, configuration file, or data workflow.
Read guide →Oct 17, 2026
URL Encoding Explained: Encode Query Parameters Safely
Learn how percent-encoding works and when to use encodeURI or encodeURIComponent for URLs and query values.
Read guide →Sep 20, 2026
UUID v4 vs UUID v1: Differences and When to Use Each
Understand random and time-based UUIDs, privacy considerations, and database performance trade-offs.
Read guide →Frequently Asked Questions
Is my data secure when using DevToolkit?
Yes. All processing is done locally in your browser using native JavaScript APIs. Your JSON, JWTs, Base64 strings, and other inputs are never sent to a server, stored, or logged.
Is DevToolkit free to use?
Yes. All tools are completely free, with no account, subscription, or paywall required.
Which tools are available?
DevToolkit currently offers JSON Formatter, JSON Validator, JSON/YAML Converter, JSON/XML Converter, JSON/CSV Converter, JWT Decoder, Base64 Converter, UUID Generator, Timestamp Converter, Regex Tester, URL Encoder/Decoder, and Hash Generator.
Can I use DevToolkit to process sensitive production data?
Tool inputs are processed locally in your browser and are not sent to DevToolkit servers. The site may still load third-party analytics or advertising services, as described in the Privacy Policy. Always exercise caution with production secrets. For JWT decoding specifically, decoding reads the payload but does not verify the token's cryptographic signature.