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Barcode Scanner Simulator – Online Enter Number & Visualize

Type a UPC or EAN number and see how a laser scanner would identify it, plus check digit validation.

Developer Tools barcode scanner simulator

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YAML to JSON Schema Converter - Online OpenAPI Infer Structure

Paste a YAML example and generate a JSON Schema draft that matches the structure. Helps build API specs. Pure client-side inference.

Converter converter JSON Schema YAML

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Browser Console Simulator - Online Practice JavaScript Logging

Type JavaScript expressions and see output like a real browser console. Supports console.log, error, warn. Use for quick testing without DevTools.

Developer Tools console debug JavaScript simulator

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CSS Animation Library Browser - Online Preview & Copy Keyframes

Browse a collection of ready-to-use CSS animations (fade, slide, bounce). Click to preview, then copy @keyframes and class to your project. Local tool.

Developer Tools animation CSS library preview

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JSON Deep Diff Checker - Online Compare & Highlight Changes

Compare two JSON objects and see added, removed, or changed keys. Visual tree view with color highlighting. Handles nested structures. Local processing.

Checker compare deep diff JSON

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Base58 Encoder & Decoder - Online Bitcoin-Style Address Tool

Encode or decode data to/from Base58 (Bitcoin alphabet). Useful for cryptocurrency address generation testing. Fully local, no data sent.

Developer Tools Base58 Bitcoin decode encode

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Base64 to CSS @font‑face Converter - Online Embed Font

Paste a Base64 encoded font string and generate the complete @font‑face CSS rule. Inline small fonts easily.

Converter Base64 CSS font @font‑face

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Webhook Tester & Inspector - Online View Incoming Payloads

Generate a temporary webhook URL (mock) and view the JSON payloads sent to it. Great for testing integrations locally.

API inspector payload tester webhook

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Device Pixel Ratio Checker - Online See Your DPR

Display your screen's current devicePixelRatio. See how it changes when you zoom. Useful for high‑res image decisions.

Developer Tools check device pixel ratio display DPR

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size‑container Demo - Online Intrinsic & Styled Queries

Explore the size‑container and inline‑size CSS properties for container queries. Understand containment contexts. Visual guide.

Developer Tools container queries CSS demo size‑container

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Skip Link Validator - Online See Bypass Blocks

Check if your site has a visible and functional skip navigation link. Key for keyboard‑only users.

Accessibility accessibility bypass check skip link

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IndexedDB Browser - Online View & Edit Client‑Side DB

Explore your website’s IndexedDB databases and object stores. Add, delete, and inspect records. Like phpMyAdmin for IndexedDB.

Debugging browser IndexedDB storage viewer

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Mac Keyboard Shortcut Visualizer – Online Modifier Key Cheatsheet

Press a combination of modifier keys and see which common macOS shortcuts use them. Learn by experimentation.

Developer Tools keyboard Mac shortcut

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SCSS to CSS Converter - Online Free Sass Compiler

Compile SCSS code to CSS directly in the browser using the official Sass.js library. Supports variables, mixins, nesting. No server upload required.

Compiler compiler CSS SASS SCSS

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SQL JOIN Temperature Tester - Online Quick Join Syntax Checker

Quickly test SQL JOIN syntax (INNER, LEFT, RIGHT, FULL) with a sample database schema. Check logic and see conceptual result set without a real DB. Local only.

Developer Tools JOIN SQL syntax tester

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IPv4 Subnetting Practice Quiz - Online CIDR & Netmask Drills

Practice calculating network ID, broadcast address, and usable IPs from a random IP/CIDR combination. Instant feedback and score tracking. Perfect for CCNA prep.

Developer Tools CIDR IP practice quiz subnet

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MySQL ENUM to TypeScript Union - Online Schema Converter

Paste a MySQL ENUM definition and get a TypeScript union type string literal. For type‑safe database schemas.

Converter converter ENUM MySQL TypeScript

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Telegram Bot Markdown/HTML Builder - Online Message Formatter

Compose messages with bold, italic, links, and code. See the raw HTML or Markdown for your Telegram bot API calls.

Developer Tools bot format message Telegram

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CSS Dynamic Island Demo - Online Pill Shape Animation

Create the iPhone Dynamic Island look‑alike with a pill that expands on hover. Pure CSS. Copy the playful code.

Developer Tools animation CSS dynamic island pill

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Font Kerning Pair Explorer - Online See Glyph Spacing

Type two letters and see if your chosen font has a kerning pair for them. Adjust tracking and see live spacing.

Developer Tools explorer font kerning pair

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Binary Number Explainer - Online Visual Bit Representation

Enter a decimal number and see a visual breakdown of bits, place values, and bitwise operations. Learn binary easily.

Developer Tools binary bits explainer visual

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SSL Certificate & Key Pair Matcher - Online Verify Match

Paste an SSL certificate and private key to verify they belong together. Check if a CSR matches a private key. All local crypto.

Developer Tools certificate key match SSL

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Emoji Background Pattern Generator - Online Repeat CSS

Select emojis and arrange them into a seamless tiling background. Copy the CSS data‑URI or download as image.

Developer Tools background CSS emoji pattern

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CSS‑in‑JS Runtime Cost Simulator - Online Render 1000 Nodes

Render 1000 styled elements using inline styles vs. CSS classes and compare time. Understand CSS‑in‑JS trade‑offs.

Developer Tools benchmark CSS‑in‑JS performance render

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Python range() to List - Online See Generated Numbers

Write a Python range expression and instantly see the list of numbers it produces. Quick playground for beginners.

Developer Tools generator list Python range

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Image Alt Text Linter - Online Check Missing & Redundant Alts

Paste an HTML snippet and get a report on missing, empty, or suspicious alt texts. Improve your image SEO and a11y.

Accessibility accessibility alt text linter SEO

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aria‑hidden Conflict Finder - Online A11y Audit

Paste HTML and detect elements with aria‑hidden='true' that contain focusable children. An easy a11y win to fix.

Accessibility a11y aria‑hidden audit conflict

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Viewport Meta Tag Simulator - Online Test Mobile Rendering

Change the viewport meta tag and see how a page would render at different device widths. Understand responsive basics.

Design meta mobile simulator viewport

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CSS Custom Property Polyfill Checker - Online IE11 Fallback

Paste your CSS and see a static fallback version where var() is replaced with the default value. For legacy support.

Developer Tools CSS variables fallback legacy polyfill

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Bitwise Calculator - Online AND OR XOR NOT Shift

Enter two hex or decimal numbers and perform bitwise AND, OR, XOR, NOT, left/right shift. See results in binary.

Calculator binary bitwise calculator shift

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Advanced Number Base Converter - Online Bin Oct Dec Hex Custom

Convert numbers between binary, octal, decimal, hex, and any custom base up to 36. With live preview of all bases.

Calculator converter custom hex number base

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URL Component Encoder/Decoder - Online encodeURIComponent

Encode or decode a string for use in a URL query parameter. See the raw and encoded versions. Dev tool.

Developer Tools component decode encode URL

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Text Scramble Effect - Online Decoding Animation

Animate text that looks like it's being decoded or scrambled before settling on the final word. Copy the JS snippet.

Design animation effect JavaScript text scramble

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<selectlist> New HTML Element Demo - Online Rich Select

Test the upcoming <selectlist> element for a fully customizable, stylable select dropdown. Experimental browser feature.

Developer Tools demo HTML new selectlist

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scroll‑state Container Query Demo - Online Test stuck/snapped

Experiment with scroll‑state container queries to style elements when they are stuck, snapped, or overflowed. Experimental.

Developer Tools container query CSS demo scroll state

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CSV to GeoJSON Converter - Online Map Data Generator

Map CSV columns with latitude/longitude to GeoJSON points. Create map‑ready data instantly. All local.

Converter converter CSV GeoJSON map

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CSS Cursor Playground - Online Preview All Pointer Styles

Hover over tiles to see every CSS cursor value in action. Quick visual reference for choosing the right UI feedback.

Developer Tools CSS cursor demo pointer reference

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Window Controls Overlay Demo - Online PWA Title Bar Customization

See how a PWA can extend content into the title bar area on desktop. Customize the window controls overlay.

Developer Tools demo PWA title bar Window Controls Overlay

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Offline Capability Checker - Online Test PWA Readiness

Check if your site has a service worker registered and if it can load offline. Quick PWA readiness assessment.

Developer Tools offline PWA service worker test

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Touch Pressure & Radius Visualizer - Online Advanced Input

Touch your screen and see the pressure and radius reported. Visualize force. Mobile developer tool.

Debugging pressure radius touch visualizer

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CSS Filter Visual Editor - Online Apply & Chain Filters

Add multiple CSS filters (grayscale, blur, hue‑rotate) to an image. See the combined effect. Copy the CSS filter value.

Developer Tools chain CSS filter editor visual

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Reporting API Demo - Online See CSP & Deprecation Reports

Send a test CSP violation report and see the ReportingObserver in action. Understand how monitoring works.

Developer Tools CSP demo monitor Reporting API

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Font Loading API Demo - Online Wait for Fonts Ready

Use the document.fonts API to check if a font is loaded. Watch the ready promise. Avoid FOUT. JavaScript demo.

Developer Tools API demo document.fonts Font Loading

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Paint Timing API Monitor - Online FP, FCP & LCP

Access the Paint Timing API and display First Paint, First Contentful Paint, and Largest Contentful Paint times. Quick perf check.

Developer Tools FCP FP Paint Timing performance

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Navigation Timing API Viewer - Online Page Load Breakdown

See your current page load broken down into DNS, TLS, request, and DOM phases. Understand where time is spent.

Developer Tools API Navigation Timing page load performance

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Window Size Detector - Online Outer & Inner Dimensions

See outerWidth, innerWidth, outerHeight, innerHeight, screenX/Y, and availWidth/Height live. Understand the viewport.

Developer Tools dimensions size viewport window

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Regex Lookaround Tester - Online Experiment with Lookahead

Practice positive/negative lookahead and lookbehind. See matches highlighted live. Master advanced regex.

Developer Tools lookahead lookbehind regex test

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Number Input Step Demo - Online See Validation Behavior

Test min, max, and step constraints on `<input type='number'>`. See how invalid values are handled. Undocumented behavior.

Developer Tools HTML number input step validation

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DNS Record Lookup - Online Query A, AAAA, MX, TXT

Query DNS records for any domain directly from your browser using DNS-over-HTTPS. See A, AAAA, MX, CNAME, and TXT. No logs.

Developer Tools DNS domain lookup records

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CSS visibility & display Demo - Online Show/Hide Effects

Compare visibility: hidden vs display: none. See how each affects layout and event listeners. Inline code.

Developer Tools CSS demo display visibility

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CSS tab‑size Property Demo - Online Control Indentation

Set tab‑size to any number and see how tabs are displayed in a pre element. Essential for code snippets.

Developer Tools CSS demo indentation tab‑size

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HTTP Headers Reference - Online Search & Descriptions

Browse a searchable list of standard HTTP request and response headers with explanations. Quick dev help.

Developer Tools cheat sheet dev HTTP headers reference

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Browser Feature Support Detector - Online Check Your Device

See a comprehensive table of which modern web APIs your current browser supports. Includes WebGPU, AVIF, and more.

Developer Tools API browser feature detection support

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HTML Table to CSV Converter - Online Extract Data

Paste an HTML table snippet and instantly get the data as CSV or JSON. Handy for scraping and data migration. Local.

Converter converter CSV extract HTML table

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Link Preview Analyzer - Online See Open Graph & Meta of Any URL

Paste a URL and see the og:title, description, image, and twitter card that will be used when shared. No server needed.

Developer Tools analyzer link preview meta Open Graph

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JSON Query Playground - Online jq‑style Filtering

Paste a JSON array and filter/transform it using a simple path expression. Extract nested values without code. Local.

Data filter JSON path query

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Web Page Resource Analyzer - Online List Assets & Size

Fetch a page and list all loaded assets (CSS, JS, images) with their sizes. See total page weight. Quick performance check.

Developer Tools analyzer page performance resources

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FedCM Demo - Online Federated Credential Management

Experiment with the Federated Credential Management API. Simulate a sign‑in flow without third‑party cookies. Privacy‑first.

API API FedCM identity sign‑in

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CSS Grid Cheatsheet – Online Interactive Template Areas

Visual reference for CSS Grid properties. Click to see code snippets and visual demos.

Cheatsheet cheatsheet CSS Grid interactive

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SVG Path D to Array – Online Extract Coordinates

Paste an SVG path d string and parse it into an array of commands and coordinates. Useful for animations.

Developer Tools coordinates d attribute SVG path