DevToolbox — free, private developer tools

Fast, private, client-side developer utilities — nothing leaves your browser.

DevToolbox is a free collection of 8 fast developer utilities that run entirely in your browser — Base64 and URL encode/decode, a JSON formatter and validator, a UUID v4 generator, a Unix timestamp converter, a SHA hash generator, a slugifier, and a JWT decoder. There is no sign-up and nothing you paste is uploaded or stored: every tool computes its result locally using standard browser APIs, so it works offline once the page has loaded.

Tools

Base64 Encode / Decode

Encode text to Base64 or decode Base64 back to text, fully in your browser.

JSON Formatter & Validator

Pretty-print, minify and validate JSON with clear, line-aware error messages.

URL Encode / Decode

Percent-encode or decode URLs and query-string components instantly.

UUID v4 Generator

Generate cryptographically-random RFC 4122 version 4 UUIDs in bulk.

Unix Timestamp Converter

Convert Unix epoch seconds or milliseconds to a human date, and back.

SHA Hash Generator

Compute SHA-1, SHA-256, SHA-384 and SHA-512 hashes of any text.

Slugify — URL Slug Generator

Turn any title into a clean, lowercase, URL-safe slug.

JWT Decoder

Decode the header and payload of a JSON Web Token without verifying the signature.

Latest from the blog

Base64 Encoding: What It Is and When to Use It

A clear explanation of Base64 encoding — how the 3-bytes-to-4-characters scheme works, the difference from URL-safe Base64, and when (and when not) to use it.

2026-06-14 Hashing vs Encryption vs Encoding: What's the Difference?

Hashing, encryption, and encoding are constantly confused. Learn what each one does, whether it's reversible, what keys it needs, and when to use which.

2026-06-14 JSON Formatting and Validation Explained (Pretty-Print, Minify, Validate)

Understand what JSON formatting and validation actually do, how to fix common parser errors like trailing commas, and when to pretty-print versus minify.

2026-06-14

Read all articles →

Why DevToolbox

Private by design. Your input never leaves the page — there are no uploads and no logging of what you type.
Fast and static. Pages are pre-rendered and tiny, so tools load instantly and keep working offline.
Standards-based. Each tool uses documented web APIs (TextEncoder, Web Crypto, JSON, the URL spec) — see our methodology for exactly how each one is computed.

About this site

DevToolbox focuses on the developer & technical utility tools developers reach for daily. Read more about the project or browse the full toolbox.