Free private developer utilities
Format, encode, decode, preview and generate developer data instantly — 100% in your browser. No uploads, no signup, completely private.
JSON Formatter
Pretty-print, validate and minify JSON in your browser.
Base64 Encode/Decode
Encode and decode UTF-8 text as Base64 without uploads.
URL Encode/Decode
Encode or decode URL components with instant validation.
JWT Decoder
Decode JWT header and payload locally without verifying signatures.
Hash Generator
Generate SHA-1, SHA-256, SHA-384 or SHA-512 hashes using Web Crypto.
UUID Generator
Generate one or many random UUID v4 values with crypto.randomUUID().
Lorem Ipsum Generator
Create placeholder words, sentences or paragraphs for mockups.
Case Converter
Convert text to upper, lower, title, camel, snake, kebab and sentence case.
Timestamp Converter
Convert Unix epoch timestamps to dates and dates back to epoch values.
Regex Tester
Test JavaScript regular expressions against sample text and inspect matches.
Markdown Preview
Preview Markdown as HTML locally using marked.
HTML Beautifier
Beautify or compact HTML, CSS and JavaScript snippets in your browser.
CSV ⇄ JSON
Convert CSV to JSON and JSON back to CSV.
Number Base Converter
Convert numbers between binary, octal, decimal, hex and any base.
YAML ⇄ JSON
Convert YAML to JSON and JSON back to YAML locally.
XML Formatter
Format XML and convert XML to JSON in your browser.
SQL Formatter
Beautify SQL queries for common dialects locally.
HTML to Markdown
Convert HTML fragments to Markdown and download .md files.
JSON Diff
Compare two JSON objects and highlight recursive changes.
HTML Entities
Encode and decode named or numeric HTML entities.
Mock Data Generator
Generate fake JSON or CSV rows for prototypes and tests.
Cron Explainer
Explain five-field cron expressions in plain English.
HTTP Status Codes
Search common HTTP status codes with descriptions.
MIME Types
Search common file extensions and MIME types both ways.
Cubic Bezier Editor
Edit CSS cubic-bezier easing curves visually.
CSS Unit Converter
Convert px, rem, em and pt with configurable base sizes.
ULID Generator
Generate sortable ULIDs individually or in bulk.
JSON to TypeScript
Infer TypeScript interfaces from a JSON sample in your browser.
JSON Schema Generator
Generate a draft-07 JSON Schema from a JSON sample.
.env ⇄ JSON
Convert a .env file to JSON and JSON back to .env locally.
cURL to Code
Convert a curl command into fetch and Python requests snippets.
Emoji Picker
Search a categorized emoji grid and click to copy.
ASCII Table
Search the full ASCII reference with dec, hex, oct and char.
String Escaper
Escape or unescape JSON, JavaScript, HTML, URL and backslash sequences.
JSON to YAML
Convert JSON to YAML and YAML back to JSON using js-yaml.
Code Formatter (Prettier)
Format JS, TS, CSS, SCSS, HTML, JSON, GraphQL, Markdown and YAML with Prettier in your browser.
JavaScript Minifier
Minify JavaScript with Terser: compress, mangle and compare sizes locally.
CSS Minifier
Minify and restructure CSS with CSSO and see how many bytes you saved.
SVG Optimizer
Optimize SVG files with SVGO, preview before and after, and download the result.
SQLite Viewer
Open .sqlite and .db files, browse tables and run SQL queries locally.
Private developer utilities for everyday work
Dev Tools is a collection of practical browser-based utilities for formatting JSON, encoding Base64, decoding JWTs, generating hashes, testing regular expressions and previewing Markdown. Every tool runs locally with client-side JavaScript, so your snippets, tokens and sample data are never uploaded or stored on a server.
Choose a tool above to clean up an API response, convert text for a URL, generate UUIDs for test fixtures, inspect timestamps or beautify HTML, CSS and JavaScript. The goal is simple: fast, free developer helpers that respect privacy and work without accounts, queues or round trips.