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100+ online utilities for developers, designers, and teams.
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View all tools →JSON Formatter
Format, beautify, and validate JSON data with syntax highlighting
Image Compressor
Compress images to reduce file size while maintaining quality. Supports JPEG,...
Base64 Encoder
Encode text or data to Base64 format instantly
Image Resizer
Resize images to exact dimensions or percentages. Supports JPG, PNG, WebP. Al...
Base64 Decoder
Decode Base64 to readable text instantly. Private - decoding happens in your ...
Mortgage Calculator
Calculate monthly mortgage payments, total interest, and view amortization sc...
UUID Generator
Generate random UUID v4 identifiers instantly
Invoice Generator
Create professional invoices in seconds. Add items, calculate totals, and dow...
Browse All Tools by Category
Converters (14 tools)
Convert between formats - encoding, decoding, data transformation
Image Compressor
Compress images to reduce file size while maintaining quality. Supports JPEG, PNG, and WebP.
Base64 Encoder
Encode text or data to Base64 format instantly
Base64 Decoder
Decode Base64 to readable text instantly. Private - decoding happens in your browser, never sent to servers.
URL Encoder
Encode text for safe use in URLs and query strings
URL Decoder
Decode URL-encoded (percent-encoded) text back to readable form
Unix Timestamp Converter
Convert Unix timestamps to dates instantly. What date is 1704067200? January 1, 2024. Free epoch to date converter - paste any timestamp and see the result.
Hex to RGB Converter
Convert hex color codes to RGB values and RGB to hex
Binary Converter
Convert between binary, decimal, hexadecimal, and octal
Markdown to HTML
Convert Markdown text to HTML markup
CSV to JSON
Convert CSV data to JSON format and vice versa
Translations to Excel
Combine JSON or YAML translation files into one Excel table. Keys in column A, each language in the next columns.
CSV Cleaner
Clean messy CSV data. Remove empty rows/columns, trim whitespace, fix delimiters.
TSV ↔ CSV Converter
Convert between tab-separated (TSV) and comma-separated (CSV) formats.
Excel Column Converter
Convert between Excel column letters and numbers. A=1, Z=26, AA=27, etc.
Generators (9 tools)
Generate UUIDs, passwords, hashes, lorem ipsum, and more
UUID Generator
Generate random UUID v4 identifiers instantly
Password Generator
Generate secure random passwords with customizable options
Hash Generator
Generate MD5, SHA-1, SHA-256, and SHA-512 hash values
Random Name Generator
Generate random names for characters, projects, usernames, or testing. First names, last names, or full names.
Random Color Generator
Generate random colors in hex, RGB, and HSL formats
Fake Data Generator
Generate realistic fake data for testing and development
Color Palette Generator
Generate harmonious color palettes for design projects
Random Number Generator
Generate random numbers within a specified range
Lorem Ipsum Generator
Generate placeholder text for design mockups and layouts
Image Tools (1 tools)
Image compression, resizing, format conversion
Validators (11 tools)
Validate JSON, XML, email addresses, and other formats
Email Validator
Check email address format instantly. Validate syntax against RFC standards. Free, private.
URL Validator
Check if a URL format is valid and well-formed
XML Validator
Validate XML syntax and check for well-formedness
IBAN Validator
Validate International Bank Account Numbers (IBAN). Check format and checksum.
IP Address Validator
Validate IPv4 and IPv6 addresses and get details
VAT Number Validator
Validate EU VAT identification numbers. Format validation for all EU countries.
Domain Validator
Validate domain name format. Check syntax, TLD, and length requirements.
Phone Number Validator
Validate phone number formats from various countries
Credit Card Validator
Validate credit card number format using Luhn algorithm
JSON Validator
Validate JSON syntax and see detailed error messages
Username Validator
Check if usernames meet requirements. Configurable rules for characters and length.
SEO Tools (1 tools)
SERP simulators, schema generators, site analyzers
Formatters (8 tools)
Format and beautify JSON, SQL, code, and text
JSON Formatter
Format, beautify, and validate JSON data with syntax highlighting
SQL Formatter
Format and beautify SQL queries online. Proper indentation, uppercase keywords, clean formatting. Free SQL formatter - paste your query and get readable SQL instantly.
XML Formatter
Format and beautify XML with proper indentation
HTML Formatter
Format and beautify HTML with proper indentation
CSS Formatter
Format and beautify CSS with proper indentation
Markdown Formatter
Clean up and prettify Markdown documents instantly. Consistent headings, proper spacing, clean output.
YAML Formatter
Format and validate YAML documents
Number Formatter
Format numbers with thousands separators and decimal places. Multiple locale formats.
CSS Tools (2 tools)
Gradient generators, box shadow builders, CSS utilities
Text Tools (16 tools)
Word counters, case converters, and text manipulation
Text to Speech
Convert text to spoken audio. Choose voices, adjust speed, and listen or download.
Case Converter
Convert text between uppercase, lowercase, title case, and more
Emoji Picker & Search
Search and copy emojis instantly. Browse by category or search by name and keywords.
Word Counter
Count words, characters, sentences, and paragraphs in text
Character Counter
Count characters online with and without spaces. See character count, word count, and text length instantly. Free character counter - no signup, works in your browser.
Text Cleaner
Remove smart quotes, non-breaking spaces, and hidden characters from copy/paste text.
Text Diff Checker
Compare two texts online and see differences highlighted. Free text diff checker - find changes between two paragraphs, documents, or code snippets instantly.
Line Sorter
Sort lines of text alphabetically, numerically, or randomly
Text Reverser
Reverse text, words, or lines in various ways
Duplicate Line Remover
Remove duplicate lines from text
Whitespace Remover
Remove extra spaces, tabs, and line breaks from text
Text Case Identifier
Detect if text is camelCase, snake_case, kebab-case, or other formats. Analyze text casing.
Slug ↔ Title Converter
Convert URL slugs to human-readable titles and vice versa. Bidirectional slug conversion.
Stopword Remover
Remove common words like 'the', 'a', 'is' from text. Useful for SEO and NLP preprocessing.
Alphabetizer
Alphabetize words within a sentence or sort lines alphabetically. Multiple sorting options.
Sentence Simplifier
Make sentences simpler or more formal. Rule-based text transformation for readability.
Business Tools (1 tools)
Invoice generators, calculators for business
Developer Tools (25 tools)
Regex testers, JWT decoders, cron explainers
Git Command Generator
Describe what you want to do in plain English and get the exact Git command. Perfect for beginners.
API Request Builder
Build and test API requests in your browser. Like Postman, but no install needed. Send GET, POST, PUT, DELETE requests.
Cron Job Generator
Build cron expressions visually. Select schedule options and get the cron syntax automatically.
Redirect Checker
Check URL redirects, follow redirect chains, and see final destinations with status codes
Regex Tester
Test and debug regular expressions with live matching and highlighting
Regex Explainer
Paste any regex and get a plain English explanation. Understand anchors, groups, quantifiers instantly.
JWT Decoder
Decode JWTs instantly in your browser. See header, payload, claims. Private - never sent to a server.
Contrast Checker (WCAG)
Check color contrast for WCAG accessibility compliance. AA and AAA conformance levels.
JSON to YAML Converter
Convert JSON data to YAML format and vice versa
Cron Expression Explainer
Understand what a cron schedule expression means in plain English
HTML Entity Encoder
Encode and decode HTML entities
HTTP Status Code Reference
Look up HTTP status codes and their meanings
Chmod Calculator
Calculate Unix file permissions in numeric and symbolic notation
MIME Type Lookup
Look up MIME types by file extension or find extensions by MIME type. Comprehensive database.
URL Parameter Extractor
Extract query parameters from URLs into table or JSON format. Parse URLs instantly.
Font Size Converter
Convert between px, em, rem, pt, and percentage font sizes. Typography unit converter.
CSS Unit Converter
Convert px to vw, vh, rem instantly. Essential for responsive CSS. Set your viewport dimensions.
JWT Generator
Generate unsigned JWTs for testing. Build custom headers and payloads for development.
JSONPath Tester
Test JSONPath expressions against JSON data. Query and filter JSON with JSONPath syntax.
Base64 Image Viewer
Preview Base64-encoded images. Paste data URI or raw Base64 to render image.
HTTP Header Explainer
Understand HTTP headers in plain English. Paste headers and get clear explanations.
JWT Explainer
Decode and explain JWTs with security focus. Understand token claims and expiration.
HTTP Method Explainer
Reference for HTTP methods (GET, POST, PUT, DELETE). When to use each method.
Subdomain Extractor
Extract subdomain, domain, and TLD from any URL. Handles .co.uk, .com.au and complex TLDs.
Token Counter
Count tokens for GPT, Claude, and other LLM models
Productivity Tools (1 tools)
Timers, typing tests, and productivity utilities
Calculators (16 tools)
Percentage, time, and unit calculators
Mortgage Calculator
Calculate monthly mortgage payments, total interest, and view amortization schedule.
Compound Interest Calculator
Calculate investment growth with compound interest. See how your money grows over time.
Meeting Cost Calculator
Calculate the real cost of meetings based on attendees, duration, and salaries. See the true price of meetings.
Pomodoro Timer
Boost productivity with the Pomodoro Technique. 25-minute work sessions with 5-minute breaks.
Countdown Timer Maker
Create countdown timers to any date. Perfect for events, deadlines, holidays, and product launches.
Percentage Calculator
Calculate any percentage instantly. What is X% of Y? Find percentage of a number, percentage change, or percent of a percentage. Free online calculator.
Age Calculator
Calculate exact age from birthdate in years, months, and days
Time Duration Calculator
Add and subtract hours, minutes, and seconds. Calculate total duration from multiple time entries.
Hourly to Salary Converter
Convert between hourly rate, monthly salary, and annual salary. Calculate your true earnings.
Date Difference Calculator
Calculate the difference between two dates
Tip Calculator
Calculate tips and split bills instantly. 15%, 18%, 20% or custom. Works on any device.
BMI Calculator
Calculate Body Mass Index with health category
Loan Calculator
Calculate loan payments, interest, and amortization
Discount Calculator
Calculate sale prices and savings from discounts
Fuel Cost Calculator
Calculate trip fuel cost based on distance and fuel consumption. Supports metric and imperial units.
Aspect Ratio Calculator
Calculate image dimensions while maintaining aspect ratio. Resize without distortion.
Marketing Tools (8 tools)
UTM builders, meta tag generators, SERP preview
Schema Markup Generator
Generate JSON-LD structured data for SEO. Create schema for FAQ, Article, Product, Organization, and more.
UTM Link Builder
Build UTM tracking links for campaign analytics
Meta Tag Generator
Generate HTML meta tags for SEO and social sharing
URL Slug Generator
Convert text to URL-friendly slugs
QR Code Generator
Generate QR codes for URLs, text, and more
Open Graph Preview
Preview how your links appear on social media
Keyword Density Checker
Analyze keyword frequency and density in text
Reading Time Calculator
Estimate reading time for articles and documents
Why Use CuriousTools?
100% Private
All processing happens in your browser. Your data never leaves your device. No server uploads, no logging, no tracking.
Instant Results
No waiting for server responses. Tools work offline and process instantly using modern browser APIs.
No Signup Required
Just open and use. No accounts, no email verification, no paywalls. Every tool is completely free.
Works Everywhere
Responsive design works on desktop, tablet, and mobile. Use your favorite tools from any device.
Free Online Developer Tools and Utilities
CuriousTools provides a comprehensive collection of free online utilities designed for developers, designers, marketers, and anyone who works with data. Our tools include JSON formatters, Base64 encoders and decoders, UUID generators, password generators, hash generators, regex testers, and many more essential utilities.
Unlike other online tools, CuriousTools processes everything locally in your browser. This means your sensitive data—API keys, passwords, personal information—never gets sent to any server. It's the privacy-first approach to online utilities.