21 tools WEB

Free Web & Code Tools

Utilities for the web stack: formatters for HTML, CSS, SQL, and XML, a JS minifier for production bundles, SVG optimization, OpenAPI validation, accessibility audits, and clean PWA checks. Your code, your markup, and your secrets stay local to your browser and never reach a server.

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21 tools in this category

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LocalAI

Accessibility Checker

Scan HTML for WCAG accessibility issues with AI-powered fix suggestions.

accessibilitya11yWEB
LocalAI

Bundle Size Analyzer

Analyze and visualize JavaScript bundle sizes with optimization suggestions.

bundlewebpackWEB
Local

URL Encoder/Decoder

Encode, decode, and parse URLs and query strings instantly.

urlencodeWEB
Local

SQL Formatter

Format, minify, and validate SQL queries with dialect support.

sqlformatWEB
Local

SVG Optimizer

Optimize, minify, and clean SVG files with configurable SVGO presets.

svgoptimizeWEB
Local

Color Converter

Convert colors between HEX, RGB, HSL, oklch, CMYK, and 16+ formats instantly.

colorconverterWEB
Local

HTML Formatter

Format, minify, and validate HTML with attribute sorting and template support.

htmlformatWEB
Local

CSS Formatter

Format, minify, and validate CSS with property sorting and SCSS conversion.

cssformatWEB
LocalAI

cURL to Code Converter

Convert cURL commands to idiomatic code across 14 programming languages instantly.

curlconverterWEB
Local

HTML to Markdown

Convert HTML to Markdown with support for GFM, CommonMark, and Obsidian syntax.

htmlmarkdownWEB
Local

HTML Entities Encoder/Decoder

Encode and decode HTML entities with named, numeric, and hex modes.

htmlentitiesWEB
Local

XML Formatter

Format, beautify, validate, minify, and convert XML to JSON with syntax highlighting.

xmlformatWEB
LocalAI

OpenAPI Validator

Validate, format, and summarize OpenAPI/Swagger specifications.

openapiswaggerWEB
Local

JS Minifier / Beautifier

Format, minify, and validate JavaScript code instantly.

javascriptjsWEB
LocalAI

Responsive Design Tester

Preview web pages across multiple device viewports instantly.

responsiveviewportWEB
LocalAI

CSS Selector Tester

Test CSS selectors against HTML with real-time matching and specificity analysis.

cssselectorWEB
LocalAI

CSS Animation Generator

Generate CSS keyframe animations with visual preview and easing functions.

cssanimationWEB
LocalAI

PWA Manifest & Service Worker Audit

Validate manifest.json, inspect service worker config, and flag installability issues.

pwamanifestWEB
Local

GitHub Actions Validator

Validate, format and summarize GitHub Actions workflow YAML files against official schemas.

githubactionsWEB
Local

Meta Tag Generator

Generate SEO meta tags, Open Graph, Twitter Cards, and JSON-LD structured data.

metaseoWEB
Local

Nginx Config Generator

Generate Nginx, Caddy & Apache reverse proxy configs with SSL & presets

nginxcaddyWEB

Web Code Guides & Technical Standards

Master workflows, understand protocol specifications, and avoid production edge-cases.

Technical Field Manuals

Automating API Contract Testing: Converting OpenAPI 3.1 to Postman Collections

Transform OpenAPI (Swagger) specifications into executable Postman Collections (v2.1). Automate contract testing, generate mock servers, and streamline API integration.

Clean HTML to Markdown for LLM & RAG Pipelines: Token Minimization & Semantic Table Extraction

Strip DOM boilerplate, convert complex HTML tables and semantic trees into clean Markdown, slash RAG embedding token costs by 60–80%, and preserve critical context for LLMs.

Content Security Policy (CSP) Headers: Production Implementation & Debugging Guide

Master Content Security Policy (CSP) headers, nonce generation, sha256 script hashing, Report-Only mode, and debugging modern Next.js and SPA violations.

Converting cURL Commands to Clean Node.js, Python, and Go HTTP Clients

Transform raw cURL commands and browser network exports into production-ready JavaScript Fetch, Axios, Python Requests/HTTPX, and Go net/http code.

De-minifying Production Stack Traces: Source Map Resolution Guide

Resolve minified JavaScript bundle errors back to original TypeScript source code using VLQ-decoded source maps, hidden source maps, and stack trace resolvers.

Debugging CORS Errors: The Complete Guide to Preflight OPTIONS & Headers

A production debugging guide to fixing missing origin headers, failed preflight OPTIONS requests, credentialed CORS mismatches, and reverse-proxy proxy pass drops.

Debugging Open Graph & Twitter Cards for Dynamic Social Previews

Master Open Graph protocol, Twitter Card meta tags, dynamic OG image generation, and crawler cache invalidation across Slack, Discord, Twitter/X, and LinkedIn.

Detecting Website Technology Stacks: Frameworks, CMS & Server Fingerprinting Guide

Learn how to detect frontend frameworks, CMS platforms, CDN edge layers, and server runtimes using DOM markers, script paths, and HTTP response headers.

Dockerfile Best Practices: Layer Caching, Multi-Stage Builds & Security Hardening

A comprehensive developer guide to writing production-grade Dockerfiles: mastering BuildKit cache invalidation, multi-stage builds, non-root execution, and security linting.

Frontend Bundle Size Optimization: Tree-Shaking, Chunk Splitting & Dead Code Elimination

Diagnose JavaScript bundle bloat, fix broken tree-shaking patterns, eliminate barrel file overhead, and optimize Core Web Vitals (INP/LCP) in Next.js, Vite, and Webpack.

Generating TypeScript Types from JSON: Schemas, Interfaces & Zod

How to generate type-safe TypeScript interfaces, Zod runtime validation schemas, and JSON Schema definitions from arbitrary JSON payloads.

GitHub Actions YAML Workflow Debugging: The Top 10 Syntax & Runtime Pitfalls

A comprehensive developer guide to identifying and fixing GitHub Actions YAML syntax errors, matrix build bugs, expression interpolation traps, and concurrency race conditions.

GraphQL Schema to TypeScript: Automated Type Generation, Operations & Codegen Guide

Generate end-to-end type safety across your GraphQL stack. Learn how to convert GraphQL SDL schemas and documents into typed queries, mutations, and resolver signatures.

Handling HTTP 429 Too Many Requests: Rate Limiting Headers, Exponential Backoff & Jitter

Diagnose and handle HTTP 429 status codes. Master IETF standard RateLimit and Retry-After headers, and implement production-grade exponential backoff with full jitter in Node.js, Python, and Go.

HAR File Analysis: How to Diagnose Slow API Endpoints & Network Bottlenecks

A practical guide to analyzing HTTP Archive (HAR) files, decoding network timing waterfalls, identifying high TTFB, and debugging slow REST and GraphQL APIs.

High-Performance CSS Keyframe Animations: Hardware Acceleration, Easing Curves & 60fps UI Patterns

A comprehensive engineering guide to CSS @keyframes animations, GPU compositor layer promotion, cubic-bezier easing mathematics, and WCAG accessibility patterns.

HTML Entity Encoding & Escaping: XSS Prevention, Unicode & Parser Nuances

Master HTML entity encoding, numeric character references, context-aware XSS escaping in body vs attributes vs JS, and HTML5 named entity parser rules.

HTTP Cache-Control & CDN Caching: The Production Guide to stale-while-revalidate, ETags & Edge Invalidation

Master HTTP caching headers, understand browser vs CDN shared cache directives (s-maxage, stale-while-revalidate, immutable), and eliminate stale content and cache poisoning bugs.

HTTP Redirects Demystified: Debugging 301 vs 308, Chains, and Redirect Loops

Master HTTP 3xx status codes: 301 vs 308 permanent redirects, 302 vs 307 temporary redirects, fixing ERR_TOO_MANY_REDIRECTS loops, and optimizing redirect chains.

Kubernetes YAML Validation: The 10 Most Common Manifest Mistakes

Diagnose and fix syntax errors, missing resource limits, selector mismatches, and schema validation failures in Kubernetes manifests before deployment.

Mastering Cron Expressions: Syntax, Timezones, and DST Gotchas

Master 5-field and 6-field cron syntax, prevent double executions during Daylight Saving Time (DST), handle UTC schedules, and debug missed server jobs.

Mastering CSS Selectors: Specificity Math, Relational :has(), and Modern Pseudo-Classes

A comprehensive developer guide to CSS selectors, specificity calculation mechanics, the :has() relational selector, forgiving selector lists, and high-performance DOM querying.

Mastering Git Merge Conflict Resolution: 3-Way Diff, Diff3 Markers & Rebase Workflows

Resolve Git merge and rebase conflicts with confidence. Master standard vs diff3 conflict markers, 3-way merge logic, and conflict prevention strategies.

Mastering JSON to C# Class Serialization: System.Text.Json, Records & .NET Best Practices

Learn how to convert JSON payloads into robust, idiomatic C# classes and records. Master System.Text.Json, JsonPropertyName, Newtonsoft.Json, nullable reference types, and custom converters.

Mastering JSON to Go Struct Serialization: encoding/json, Struct Tags & Custom Unmarshaling

Learn how to convert JSON payloads into robust, idiomatic Go structs. Master struct tags, omitempty edge cases, pointer nullability, and custom unmarshaling.

Mastering Number Base Conversions: Binary, Hex, Two's Complement & IEEE 754 Floating Point

A comprehensive developer guide to positional numeral systems, arbitrary-precision BigInt radix conversions, two's complement signed arithmetic, and IEEE 754 float inspection.

Mastering Responsive Web Design: Viewports, CSS Breakpoints & Multi-Device Testing

A comprehensive developer guide to responsive web design, covering layout vs visual viewports, modern CSS media queries, container queries, fluid typography, and viewport testing strategies.

Mastering SQL Execution Plans: Reading EXPLAIN ANALYZE, Index Scans & Query Optimization

Diagnose slow database queries by decoding EXPLAIN (ANALYZE, BUFFERS) output trees, optimizing composite indexes, understanding bitmap heap scans, and eliminating sequential scans.

Model Context Protocol (MCP) Server Schema Validation & Tool-Calling Debugging

A technical guide to authoring, validating, and debugging JSON Schema tool definitions for Model Context Protocol (MCP) servers in AI agents and LLM applications.

Modern CSS Color Spaces: Mastering OKLCH, Display P3, Hex & HSL Conversions

A comprehensive developer guide to modern web color spaces: understanding OKLCH perceptual uniformity, Display P3 wide gamut, sRGB conversions, and accessible UI palettes.

OpenAPI to TypeScript: Automated Type Generation, REST Contracts & Zod Guide

Generate end-to-end type safety from OpenAPI and Swagger specs. Learn how to convert OAS 3.0/3.1 JSON/YAML schemas into typed fetch clients, Zod validators, and path types.

PWA Web App Manifest & Service Worker Guide: Icons, Offline Caching & Installability

Build installable Progressive Web Apps that pass Lighthouse audits. Master web app manifest configurations, maskable icons, and service worker caching strategies.

Server-Sent Events (SSE) vs WebSockets: Streaming Architecture for LLM & Real-Time APIs

Master unidirectional SSE vs bidirectional WebSockets for modern applications. Learn HTTP/2 multiplexing, automatic reconnection, Nginx proxy buffering gotchas, and token-by-token LLM streaming.

SVG Optimization & Sanitization: Production SVGO Configs, viewBox & XSS Hardening

Strip metadata bloat and invisible paths using SVGO, sanitize malicious script tags and inline event handlers to prevent SVG-based XSS, and configure responsive viewBox scaling.

URL Encoding & Query Strings: Mastering RFC 3986, encodeURIComponent & URLSearchParams

Demystify percent-encoding rules, avoid double-encoding pitfalls, master + vs %20 space representations, and serialize complex nested objects and arrays for REST query strings.

Visual Text Diffing, Unified Diff Syntax & Git Patch Workflows

Master code diff algorithms (Myers, Patience, Histogram), unified diff patch anatomy (@@ coordinates), side-by-side vs inline comparison, and patch workflows.

Visualizing and Debugging Complex JSON Schemas: $defs, Recursion, and OpenAPI 3.1

Master JSON Schema visualization and debugging: resolve complex $defs pointers, catch recursive circular loops, inspect validation constraints, and render OpenAPI diagrams.

WCAG 2.2 Accessibility Audit Checklist: Automated & Manual Testing Guide

A comprehensive developer guide to WCAG 2.2 accessibility compliance: new success criteria, color contrast ratios, keyboard navigation, ARIA patterns, and CI/CD audit workflows.

Webhook Security & HMAC Signature Verification: Production Implementation Guide

Master webhook security: implement HMAC-SHA256 signature verification, prevent replay attacks with timestamp headers, avoid raw-body parser bugs, and secure asynchronous API callbacks.

WebP vs AVIF vs SVG: Modern Web Image Optimization & Compression Guide

Optimize Core Web Vitals (LCP), compare AVIF vs WebP compression and decoding speeds, strip EXIF metadata, and implement responsive picture elements.

XML Formatting, Validation & XXE Prevention: The Production Engineering Guide

Master XML formatting standards, well-formedness rules vs XSD validation, namespace resolution, CDATA handling, and server-side XXE attack prevention.

RFC Standards & Terminology

AI Tokens (LLM Tokenization & Context Windows)AI & Machine LearningAVIF Image FormatWeb StandardsBase64 EncodingEncodingBrotli (br) Compression AlgorithmEncodingC# Classes, Records & JSON Serialization in .NETDeveloper ToolsColor Spaces & Models (RGB, HSL, OKLCH, Hex)Web StandardsCross-Origin Resource Sharing (CORS)NetworkCron Expressions & Crontab SyntaxDevOpsCSS (Cascading Style Sheets)Web StandardsCSS Keyframes (@keyframes, Animation Timing & Hardware Acceleration)Web StandardsCSS Selectors (Syntax, Combinators, Specificity & Pseudo-Classes)Web StandardscURL (Client URL) Command & LibraryNetworkingDockerfile (Container Image Build Specification)DevOpsGitHub Actions (CI/CD & Workflow Automation)DevOpsGo Structs & JSON Serialization in GolangDeveloper ToolsHTML (HyperText Markup Language)Web StandardsHTML Entities & Character EncodingWeb DevelopmentHTTP Headers (Request & Response Metadata)NetworkingMarkdown (Lightweight Markup Language)Web DevelopmentOAuth 2.0 Authorization FrameworkSecurityOpen Graph Protocol (OGP, Social Meta Tags & Link Unfurling)Web StandardsOpenAPI Specification (formerly Swagger)API StandardsProof Key for Code Exchange (PKCE)SecurityPWA (Progressive Web Application)Web StandardsQR Code (Quick Response Code)IdentifiersSoftware Bill of Materials (SBOM)Developer ToolsSemantic Versioning 2.0.0 (SemVer)Developer ToolsServer-Sent Events (SSE) & EventSource APINetworkService Worker (PWA Background Worker & Offline Caching)Web StandardsJavaScript Source Maps (V3 Specification)Developer ToolsSQL (Structured Query Language)DatabaseStack Trace (Error Call Stack & Traceback)Developer ToolsSVG (Scalable Vector Graphics)Web StandardsTech Stack (Web Technology Fingerprinting & Architecture)ArchitectureTree Shaking & Dead Code Elimination in JavaScript BundlersDeveloper ToolsURL Encoding (Percent-Encoding)EncodingViewport (Layout vs Visual Viewport & Responsive Design)Web StandardsWebAssembly (WASM) Binary Instruction FormatDeveloper ToolsWebhooks (HTTP Push Notifications & Reverse APIs)NetworkingWebP Image FormatWeb StandardsXML (Extensible Markup Language)Data FormatsYAML (YAML Ain't Markup Language)Data Formats

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Frequently Asked Questions

Are the web & code tools free?+

Yes, all web & code tools are free with no limits. SQL formatting, URL encoding, JS minification, and validation all run directly in your browser.

Can I validate OpenAPI specs with these tools?+

Yes. The OpenAPI validator checks your spec for structural issues that violate the spec, and the PWA audit validates manifests and service workers.

Do I need to sign up to use the web tools?+

No. Every web & code tool works instantly from a paste, with no account and no data uploads.