Fully free developer utilities

A black-and-white command center for everyday web work.

Format payloads, inspect tokens, generate secure values, build SEO snippets, preview responsive layouts, and handle the small jobs that slow shipping down.

Launch Featured Tool Explore 15 Tools
15 functional tools
13 workflow groups
0 required signups
Local secret-safe utilities
Tool catalog

Choose what you need

Responsive Data Web Encoding Auth Crypto IDs Time Accessibility CSS Text SEO Security
Responsive Viewport Lab

Preview websites across device classes, display sizes, custom breakpoints, and orientations.

Open Tool Data JSON Formatter

Validate, format, minify, and inspect JSON payloads with a readable error line.

Open Tool Web URL Toolkit

Encode, decode, and parse URLs, query strings, hosts, paths, and hash fragments.

Open Tool Encoding Base64 Converter

Convert plain text to and from Base64 with URL-safe support.

Open Tool Auth JWT Inspector

Decode JWT headers and payloads locally to inspect claims and token timing.

Open Tool Crypto Hash Generator

Generate SHA digests in the browser using the Web Crypto API.

Open Tool IDs UUID Generator

Create batches of cryptographically random UUID v4 values.

Open Tool Time Timestamp Converter

Convert Unix timestamps, milliseconds, ISO strings, UTC, and local dates.

Open Tool Accessibility Contrast Checker

Check foreground and background color ratios against WCAG AA and AAA targets.

Open Tool CSS CSS Clamp Builder

Generate fluid clamp values from min and max sizes across viewport widths.

Open Tool Text Regex Tester

Test JavaScript regular expressions and inspect match groups in real time.

Open Tool Encoding HTML Entities

Encode unsafe characters for HTML or decode entities back into readable text.

Open Tool SEO Meta Tag Builder

Build title, description, canonical, Open Graph, and Twitter card tags.

Open Tool SEO Robots.txt Builder

Generate robots.txt directives for crawlers, paths, crawl delay, and sitemaps.

Open Tool Security Password Generator

Generate strong random passwords with length and character-set controls.

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