152 Free Online Tools

Developer Tools & Utilities

Accelerate your workflow with instant browser-based coding tools. Format JSON, debug API endpoints, validate regular expressions, generate configurations, and inspect network records with client-side privacy.

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converters

YAML to JSON Converter

Convert YAML to JSON with real-time validation and syntax highlighting

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developers

Iframe Generator

Generate responsive, secure iframe embed code with sandbox flags and preview

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developers

Box Shadow Generator

Create multi-layer CSS box-shadows with presets, inset support, and live preview

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number generators

3 Digit Random Number Generator

Generate random 3-digit numbers with advanced options

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number generators

4 Digit Random Number Generator

Generate random 4-digit numbers instantly

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number generators

5 Digit Random Number Generator

Generate random 5-digit numbers with filters

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number generators

6 Digit Random Number Generator

Generate random 6-digit numbers for PINs and codes

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number generators

7 Digit Random Number Generator

Generate random 7-digit numbers for local phone mockups and raffles

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number generators

8 Digit Random Number Generator

Generate random 8-digit numbers for 2FA backup codes and date stamps

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developers

ASCII to HEX Converter

Translate ASCII strings to hexadecimal or decode hex payloads back to readable text

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developers

IP Lookup Tool

Reveal IP geolocation, ISP, ASN, timezone, and security flags with one click

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converters

JSON to CSV Converter

Convert JSON data to CSV format

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converters

Markdown to HTML Converter

Convert Markdown to HTML instantly

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converters

CSV to HTML Table Generator

Convert CSV data to HTML tables

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developers

JSON Formatter

Format and validate JSON data

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developers

JWT Token Decoder

Decode and inspect JWT tokens

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developers

Hash Generator

Generate MD5, SHA-1, SHA-256 hashes

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developers

API Endpoint Tester

Test REST API endpoints

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developers

CSS Minifier

Minify CSS code for production

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developers

HTML Entity Encoder/Decoder

Encode and decode HTML entities

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developers

HTTP Status Code Explainer

Understand HTTP status codes

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developers

Random JSON Generator

Generate random JSON data for testing

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developers

WordPress Hash Generator

Create and verify WordPress-compatible phpass password hashes in the browser

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developers

DNS Lookup Tool

Query A, AAAA, MX, NS, TXT, and CNAME records with resolver diagnostics

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developers

MX Lookup Tool

Check MX records and mail routing priorities for any domain

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developers

NS Lookup Tool

Validate authoritative nameserver delegation records for domains

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developers

Reverse IP Lookup Tool

Resolve PTR records to map IPv4 and IPv6 addresses back to hostnames

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developers

MAC Address Lookup Tool

Lookup device vendors from MAC OUI prefixes with searchable directory support

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developers

HTML Minifier

Minify HTML code with whitespace, comment, and attribute cleanup controls

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developers

HTTP Header Checker

Inspect response headers, redirects, and security header coverage for any URL

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developers

Browser Window Size Checker

Measure live viewport size, DPR, and active responsive breakpoint

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developers

Screen Resolution Tester

Preview websites at common device resolutions and custom viewport sizes

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developers

JSON Path Tester

Evaluate JSONPath expressions against JSON documents with result previews

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developers

IEEE-754 Analysis Tool

Break float32 and float64 values into sign, exponent, and mantissa bits

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developers

URI Template Parser

Expand URI templates into real URLs with editable path and query variables

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developers

Redirect Generator

Generate redirect snippets for Apache, Nginx, Netlify, Vercel, JS, and HTML

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developers

HTML Viewer

Render and preview raw HTML code inside a safe iframe

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developers

Domain IP Lookup

Resolve IPv4 and IPv6 addresses for any hostname or website domain

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seo tools

Meta Tag Generator

Generate SEO meta tags

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seo tools

Keyword Density Checker

Analyze keyword density in content

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seo tools

Long Tail Keyword Generator

Generate long-tail keyword ideas

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seo tools

Question Keyword Generator

Generate question-based keywords

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seo tools

Local Keyword Modifier

Add local modifiers to keywords

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seo tools

Autocomplete Keyword Suggester

Get autocomplete keyword suggestions

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validators

Credit Card Validator & Luhn Checker

Validate credit card numbers using the Luhn algorithm for payment sandbox testing

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validators

Password Strength Checker

Check password strength and security

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validators

XML Validator

Validate, prettify, highlight, and minify XML feeds, SOAP envelopes, and sitemaps

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validators

Color Contrast Checker

Check color contrast for accessibility

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seo tools

Robots.txt Generator

Generate custom robots.txt files with crawl rules and sitemaps

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seo tools

Open Graph Meta Tag Generator

Generate Facebook Open Graph & Twitter Card meta tags with live card preview

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developers

.htaccess Redirect Generator

Generate 301, 302, HTTPS, and WWW rewrite rules for Apache web servers

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converters

CSV to JSON Converter

Convert CSV spreadsheets into clean, formatted JSON arrays or objects

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developers

JavaScript Minifier

Minify JavaScript code to reduce file size and increase load speed

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seo tools

Schema.org JSON-LD Generator

Generate Google-rich snippet Schema.org JSON-LD structured data code

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developers

SQL Formatter & Prettifier

Format, beautify, and clean up unformatted SQL queries for MySQL, Postgres, and SQLite

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developers

Markdown Table Generator & CSV Converter

Create, format, and convert Markdown tables visually for GitHub READMEs and docs

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developers

Cron Expression Generator & Explainer

Build, test, and translate crontab cron expressions with instant plain-English explanations

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developers

User Agent Parser & Detector

Parse HTTP User-Agent strings to detect browser, version, OS, engine, and device type

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developers

cURL to JavaScript Fetch & Axios Converter

Convert cURL commands into JavaScript fetch(), Axios, Python requests, and PHP code

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converters

HTML to Markdown Converter

Convert raw HTML markup and web articles into clean Markdown text

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generators

CSS Glassmorphism UI Generator

Design modern frosted glass UI elements with backdrop-filter blur and transparency controls

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developers

CSS Clamp() Calculator & Fluid Typography Generator

Calculate CSS clamp() formulas for responsive fluid typography and spacing

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converters

JSON to TypeScript Interface Generator

Convert raw JSON objects into strongly-typed TypeScript interfaces and type aliases

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developers

Subnet Calculator (IPv4 CIDR & Netmask)

Calculate IPv4 subnets, CIDR blocks, usable host ranges, broadcast addresses, and binary netmasks

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seo tools

Google SERP Simulator & Snippet Previewer

Preview how your page appears on Google desktop and mobile search results with pixel width checks

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developers

Security Headers Generator & CSP Builder

Generate hardened HTTP security headers (CSP, HSTS, X-Frame-Options) for Nginx, Apache, and Next.js

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developers

CSS Gradient Generator & Color Palette Maker

Create linear, radial, and conic CSS gradients with multi-stop color controls and Tailwind export

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developers

Aspect Ratio Calculator & Dimension Resizer

Calculate proportional aspect ratios, CSS padding-top hacks, and display dimensions

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developers

Regex Tester & Regular Expression Matcher

Test, validate, and debug regular expressions in real-time with capture groups and flags

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developers

Cron Expression Explainer & Schedule Humanizer

Translate crontab schedules into plain English sentences and view upcoming execution times

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developers

UTM Parameter Parser & URL Builder

Inspect, parse, edit, and rebuild Google Analytics UTM tracking links and query parameters

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developers

Cryptographic Hash Identifier & Analyzer

Identify MD5, SHA-1, SHA-256, bcrypt, Argon2, and checksum algorithms with security ratings

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developers

SVG to PNG Converter Online

Convert vector SVG code or files into high-resolution PNG or JPEG images with transparency

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developers

Linux Chmod Permissions Calculator

Generate octal and symbolic Linux file permissions with copyable bash terminal commands

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developers

CSV to SQL Converter & Table Generator

Convert CSV data into SQL CREATE TABLE schemas and multi-row batch INSERT INTO statements

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developers

Code to Image Converter

Convert code snippets into beautiful social media screenshots with themes, gradients, and window frames

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developers

CSS Clip-Path Generator & Polygon Maker

Create custom geometric shapes, diagonal sections, and polygon masks with draggable visual control points

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developers

CSS Neumorphism & Soft UI Generator

Design tactile Soft UI cards, buttons, and elements with dual directional highlights and box-shadows

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developers

CSS Border-Radius & Fancy Blob Generator

Generate fluid organic shapes and keyframe morphing animations with the 8-value border-radius syntax

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developers

CSS Animation & Keyframe Generator

Build hardware-accelerated CSS keyframe animations with easing curves, duration controls, and live element preview

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developers

HTML to JSX Converter

Transform standard HTML5 and SVG code into clean React JSX with className mapping and style objects

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developers

Image Color Extractor & Palette Generator

Extract dominant color palettes and inspect individual pixel hex codes from any image with an eyedropper

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developers

Dummy JSON Generator

Generate realistic mock JSON datasets for frontend UI prototypes, database seeding, and REST API testing

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developers

SVG Path Visualizer & Inspector

Inspect and visualize SVG path commands (M, L, C, Z) on an interactive coordinate grid with length calculation

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developers

SVG Optimizer & Minifier

Clean and minify bloated SVG vector code from Illustrator and Figma for high-speed web production

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seo tools

Social Share & Open Graph Previewer

Simulate social links on Twitter, Facebook, LinkedIn, Discord, and Google SERPs with copyable meta tags

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developers

Favicon & Apple Touch Icon Generator

Create browser tab favicons and mobile app icons from emojis or initials with multi-size PNG bundle downloads

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developers

Audio Tone Generator & Frequency Synthesizer

Generate pure sound frequencies from 20 Hz to 20,000 Hz with real-time oscilloscope waveform visualizer

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developers

.env to Docker Compose Converter

Transform .env files into Docker Compose configurations and generate sanitized .env.example templates

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productivity

Capital Gains Tax Calculator

Calculate short-term vs long-term capital gains tax on stocks, crypto, and real estate with NIIT thresholds

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developers

NGINX Config Generator

Generate production-ready NGINX server blocks for reverse proxies, Single Page Apps, SSL/TLS, and WebSockets

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developers

Dockerfile Generator

Generate optimized, multi-stage Dockerfiles with security hardening, layer caching, and automatic .dockerignore creation

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developers

CIDR IP Range Calculator

Calculate IPv4 subnet ranges, network addresses, broadcast boundaries, usable hosts, and binary bitmasks

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developers

Password Entropy Calculator

Calculate Shannon entropy bits, character pool sizes, and realistic GPU brute force cracking times according to NIST standards

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developers

CSP Header Generator

Build hardened Content Security Policy headers for Nginx, Next.js, and Apache with instant security audit scoring

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developers

JSON to Zod Schema Converter

Convert JSON payloads into TypeScript Zod validation schemas, UUID checkers, email rules, and inferred types

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productivity

CSS Mesh Gradient Generator

Create fluid, multi-point aurora mesh gradients with interactive node coordinates, live CSS export, and HD wallpaper downloads

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developers

CSR & OpenSSL Command Generator

Generate Certificate Signing Requests (CSR) and zero-trust OpenSSL CLI commands with Subject Alternative Names (SANs)

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developers

Cloud Storage Pricing Calculator

Compare monthly storage, egress bandwidth, and API request costs across AWS S3, Cloudflare R2, Azure Blob, GCP, and Wasabi

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developers

Kubernetes Resource Calculator

Calculate pod CPU, memory requests, limits, cluster overcommit ratios, and node capacity planning with YAML export

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developers

SQL to Prisma Schema Converter

Convert SQL CREATE TABLE DDL statements into Prisma schema models with primary keys, relations, and enums

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developers

.gitignore Generator

Generate production-ready .gitignore files for Node, Python, Next.js, Rust, Go, macOS, and IDEs with custom rule merging

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developers

DNS Record Generator

Generate BIND, Cloudflare, and RFC-compliant zone records for A, AAAA, CNAME, MX, TXT, SPF, and DKIM

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seo tools

Sitemap XML Generator

Generate schema-compliant XML sitemaps with custom priorities, change frequencies, and bulk URL importing

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developers

SSH Key Generator

Generate secure Ed25519 and RSA 4096 SSH key pairs in-browser with automated OpenSSH terminal commands

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developers

Base58 Encoder & Decoder

Encode and decode Bitcoin, Solana, and IPFS Base58 strings to text or hex with instant client-side validation

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developers

Base32 Encoder & Decoder

Encode and decode RFC 4648 Base32 strings and 2FA TOTP secret keys to plain text or hex with instant conversion

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developers

HAR File Viewer

Inspect HTTP Archive (.har) logs, analyze network waterfall timings, and debug HTTP errors with 100% client-side privacy

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developers

SVG to JSX Converter

Transform raw SVG code into production-ready React JSX and TypeScript TSX components with camelCase attributes

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productivity

CSS Triangle Generator

Generate pure CSS border triangles, tooltip arrows, and dropdown carets with live preview and Tailwind CSS export

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productivity

CSS Text Shadow Generator

Design multi-layer CSS text shadows, neon glow, and 3D typography effects with real-time visual preview

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developers

HTML Table Generator

Build responsive HTML tables, modern Tailwind CSS layouts, and GitHub Markdown tables with an interactive WYSIWYG editor

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converters

TSV to JSON Converter

Convert Tab-Separated Values (TSV) from Excel or datasets into structured JSON arrays and keyed objects

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developers

SemVer Version Calculator

Calculate Semantic Versioning release bumps, evaluate caret (^) and tilde (~) ranges, and audit dependency constraints

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seo tools

Hreflang Tag Generator

Generate valid HTML hreflang link tags and XML sitemap hreflang blocks for multi-language and international SEO websites.

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seo tools

Canonical Tag Generator

Create valid canonical URL link tags to prevent duplicate content penalties, consolidate PageRank, and specify preferred search index URLs.

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developers

CSS Flexbox Generator

Interactive visual flexbox playground to tweak flex direction, wrap, justify-content, align-items, and export clean CSS.

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developers

CSS Grid Generator

Visual 2D CSS grid layout builder to configure rows, columns, gaps, and fr units with instant copyable CSS and HTML.

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developers

CSS Cubic-Bezier Curve Generator

Interactive cubic-bezier timing curve visualizer with physics animation previews and CSS transition code export.

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developers

SVG Wave Generator

Create smooth, organic multi-layered SVG waves and gradient section dividers for websites with instant SVG and CSS export.

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developers

WCAG Color Contrast Checker

Test foreground and background color pairs against WCAG 2.1 AA and AAA standards with visual text simulations and contrast ratios.

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developers

SSL Certificate Decoder

Inspect X.509 PEM certificates, check expiration countdowns, SAN domains, and cryptographic SHA-256 fingerprints with zero server logs.

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developers

cURL to Python Converter

Transform cURL command lines into clean, production-ready Python requests, async HTTPX, or Node.js fetch code in seconds.

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developers

Crontab Schedule Debugger

Translate 5-field cron expressions into human-readable English, calculate next execution dates, and test crontab syntax effortlessly.

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developers

JSON to YAML Converter

Convert JSON to YAML and YAML to JSON in real time. Fast, secure, client-side formatting for Kubernetes, Docker, and CI/CD.

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text tools

Title Capitalization Tool

Capitalize headlines and article titles following Chicago, AP, APA, and MLA editorial rules automatically.

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developers

ULID Generator and Decoder

Generate and decode 128-bit sortable Crockford Base32 ULIDs and extract millisecond timestamps.

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developers

Webhook Signature Generator & Verifier

Generate and verify HMAC SHA-256 webhook signatures for Stripe, GitHub, Shopify, and custom endpoints.

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developers

TCP/UDP Port Number Lookup

Search standard TCP/UDP port numbers (0-65535), default database ports, protocols, and security risks.

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developers

Dockerfile Linter & Optimizer

Lint Dockerfiles for root user security, layer cache optimization, and multi-stage image shrinking.

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developers

SQL Injection (SQLi) Payload Explainer

Analyze SQL injection attack vectors with parser syntax breakdowns and secure parameterized code fixes.

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developers

CORS Header Generator

Generate production-ready Cross-Origin Resource Sharing (CORS) headers for Express, Nginx, Next.js, and Cloudflare.

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developers

JWT Token Generator

Generate, inspect, and sign JSON Web Tokens (JWT) with custom claims and browser-side HMAC-SHA256.

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developers

SSL Pinning Hash Generator

Calculate Subject Public Key Info (SPKI) SHA-256 pins for Android network_security_config and iOS TrustKit.

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developers

DNS SPF Record Generator

Build RFC 7208 compliant SPF DNS TXT records with Google, Microsoft, and SendGrid 10-lookup validation.

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developers

Git Merge Conflict Resolver

Resolve Git merge conflict markers (<<<<<<< HEAD, =======, >>>>>>>) side-by-side in your browser.

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productivity

Opportunity Zone Tax Calculator

Calculate Qualified Opportunity Zone (QOZ) capital gains tax deferral, tax-free basis step-ups, and 10-year net IRR returns.

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developers

Subnet Mask & Wildcard Calculator

Calculate IPv4 subnets, inverted wildcard masks, CIDR network IDs, usable host ranges, and Cisco IOS statements.

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developers

Kubernetes Ingress YAML Generator

Generate production-grade Kubernetes Ingress YAML manifests with cert-manager Let's Encrypt TLS and Nginx annotations.

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developers

Redis Memory Sizing Calculator

Calculate Redis RAM requirements by data structure (Strings, Hashes, Sets, ZSets) accounting for jemalloc and cloud nodes.

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developers

Argon2 Hash Generator & Tuning Tool

Generate and configure RFC 9106 Argon2id password hashes with memory, iteration, parallelism, and OWASP compliance auditing.

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developers

Terraform Provider Generator

Generate Terraform provider blocks, remote state S3/DynamoDB backends, VPC networks, and security groups in clean HCL.

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developers

Black-Scholes Option Pricing Calculator

Calculate theoretical European Call and Put option prices with full Delta, Gamma, Theta, Vega, and Rho Greeks.

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developers

SOC 2 Compliance & Audit Cost Estimator

Estimate Year 1 and ongoing SOC 2 Type 1 and Type 2 compliance costs, auditor fees, pentests, and tooling.

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developers

Independent Contractor Misclassification Risk Calculator

Assess 1099 contractor misclassification legal risk against DOL 6-factor standards and model back-tax penalties.

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developers

SaaS Quick Ratio Calculator

Calculate your SaaS Quick Ratio: (New MRR + Expansion MRR) / (Churned MRR + Contraction MRR) and benchmark growth.

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developers

AWS Lambda Serverless Cost Calculator

Calculate serverless execution costs in GB-seconds, compare x86 vs Graviton2 ARM pricing, and forecast cloud spend.

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developers

FinCEN BOI Exemption & Deadline Checker

Check if your LLC or Corporation is exempt from FinCEN BOI reporting under the Corporate Transparency Act.

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developers

Non-Compete Enforceability Checker

Check if your employee non-compete clause is legally enforceable under state laws, wage thresholds, and FTC rules.

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productivity

UK Capital Gains Tax (CGT) Property & Shares Calculator

Calculate HMRC Capital Gains Tax on residential buy-to-let properties (18%/24%) and shares with the £3,000 allowance.

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developers

SaaS Magic Number & Sales Efficiency Calculator

Calculate your SaaS Magic Number and CAC Payback period to benchmark Go-To-Market sales efficiency.

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developers

Cloud Data Egress Cost Calculator

Compare data transfer out bandwidth fees across AWS, Azure, Google Cloud, and Cloudflare Zero Egress.

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Why Use Stilest Developer Tools?

Every tool in our Developer Tools collection is built specifically for creators, developers, and everyday users who demand fast, reliable utilities without bloated software installs, account creation gates, or hidden paywalls. By performing operations client-side in modern WebAssembly and native JavaScript engines, your data remains securely on your device without transmitting sensitive text, tokens, or code to third-party cloud servers.

No Sign-up Required

Jump straight to solving your problem. All tools are immediately interactive on page load without email verification or registration.

Mobile & Desktop Optimized

Clean responsive layouts engineered for fast performance and high usability on tablets, smartphones, and high-resolution monitors.