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Web Tools Calculate network address ranges, broadcast IPs, netmasks, and usable host counts from CIDR blocks. Web Tools Generate Apache basic auth credentials and common redirect rules (Enforce HTTPS, Remove www, 301 Redirects). Web Tools Quick interactive lookup for standard network ports, transport protocols (TCP/UDP), and services. Developer Format, beautify, and minify SQL queries for MySQL, PostgreSQL, SQLite, and MS SQL Server online. Developer Compress HTML and CSS payload sizes or format minified code cleanly online. Developer Minify JS and TS code payloads or un-minify obfuscated scripts online. Developer Convert configuration files bi-directionally between YAML and JSON formats online. Developer Convert Markdown text to HTML code with live visual preview online. Developer Convert images to Base64 Data URIs or decode Base64 strings back to downloadable images online. Developer Format, prettify, and validate GraphQL queries, mutations, and schemas online. Developer Format and pretty-print API responses for debugging, testing, and cleaner JSON output. Developer Encode text to Base64 or decode Base64 content back to plain text instantly. Creative Create polished short bios for social profiles, portfolios, and professional introductions. Creative Generate catchy business name ideas for startups, brands, and new ventures. Developer Build cron expressions for scheduling jobs, tasks, and automation workflows. Finance Convert between major currencies for travel, budgeting, pricing, and estimates. Date & Time Convert Nepali Bikram Sambat dates to Gregorian dates and vice versa. Marketing Create a polished email signature with your contact details and branding. Finance Calculate GST or VAT amounts and totals quickly for invoices and purchases. Developer Generate MD5 and SHA-256 hashes for strings, passwords, and content verification. Marketing Generate relevant hashtags for social media posts and marketing campaigns. Finance Create simple invoices for freelance work, services, and small businesses. Developer Format and validate JSON online with a clean, free developer-friendly interface. Developer Decode JWT headers, payloads, and signatures to inspect authentication tokens safely. SEO Check keyword density in content to improve SEO relevance and readability. Finance Estimate loan EMIs, total interest, and repayment totals for better budgeting. Finance Convert between land measurement units like aana, ropani, bigha, kattha, and square feet. Web Tools Create HTML search engine meta tags (title, description, keywords, robots) for your pages. SEO Preview Open Graph tags and social share cards for Facebook, LinkedIn, and X. Finance Estimate salary, deductions, and take-home pay for payroll planning. Finance Calculate profit, margin, and markup percentages for pricing and business planning. QR & Barcode Generate custom QR codes for URLs, text, and simple messages with styling choices. QR & Barcode Scan and decode QR codes instantly using your camera or by uploading an image. QR & Barcode Generate WiFi QR codes to share network names and passwords securely. QR & Barcode Generate QR codes to initiate emails with pre-filled subject and body. QR & Barcode Generate QR codes to send pre-defined text messages to specific phone numbers. QR & Barcode Generate contact information vCard QR codes for quick scans. QR & Barcode Generate standard barcodes including CODE128, CODE39, EAN-13, and UPC. QR & Barcode Scan and read barcodes from images or live camera streams in your browser. Developer Test regular expressions against sample text and inspect matching results instantly. Web Tools Generate standard robots.txt files with crawl directives and sitemap locations. Web Tools Generate clean, valid XML sitemaps from a list of page URLs for search engines. Text Tools Generate clean, SEO-friendly URL slugs from titles, names, and phrases. Creative Create short, catchy thumbnail text ideas for YouTube and digital content. Marketing Create campaign URLs with UTM parameters for analytics and marketing tracking. Developer Generate version 4 UUIDs for databases, APIs, and system identifiers. Creative Create catchy YouTube title ideas for videos, tutorials, and channel content. Security Generate secure, random passwords with customizable length, symbols, and character sets client-side. Security Generate custom API keys with custom prefixes, lengths, and secure random byte formats. Security Generate secure random CSRF tokens for web forms and API endpoints. Security Generate cryptographically secure random tokens for sessions, passwords, and identifiers. Security Generate single or batch RFC 4122 version 4 UUIDs with formatting and casing options. Security Generate RSA public and private key pairs in PEM format client-side using Web Cryptography API. Security Encrypt plaintext securely using AES (GCM/CBC) algorithms directly in your browser. Security Decrypt AES-encrypted ciphertext using a passcode and initialization vector (IV) client-side. Security Decode and validate JSON Web Tokens (JWT) to check header details, payload claims, and signature validity. Security Analyze and identify unknown cryptographic hash formats such as MD5, SHA-1, SHA-256, and bcrypt. Web Tools Parse any URL string client-side to extract the protocol, host, port, path, query parameters, and hash. Web Tools Shorten long URLs quickly and safely using public url shortening API integration. Web Tools Build campaign URLs with custom UTM parameters (source, medium, campaign name) for tracking. Web Tools Generate Open Graph meta tags to customize social share appearances on Facebook and LinkedIn. Web Tools Generate Twitter Card HTML meta tags to optimize your site share cards on X. Web Tools Inspect web page source code to identify and check its canonical URL tags. Web Tools Trace HTTP redirect paths (301, 302, etc.) of any URL and view intermediate hops. Web Tools Query standard DNS records (A, AAAA, MX, TXT, CNAME, NS) for any domain name. Web Tools Query raw domain registration records and registrar contact information via WHOIS protocol. Web Tools Analyze a domain SSL/TLS certificate to extract validity dates, issuing authorities, and security states. Web Tools Geolocate any IP address or domain to get city, country, coordinates, and ISP details. Web Tools Parse and inspect user agent strings to extract browser, operating system, and device details. Web Tools Inspect raw HTTP response headers of any URL and run security header validation. Web Tools Test latency and connection response times to any web host via TCP handshake measurements. Unit Converters Convert between length and distance units such as meters, kilometers, miles, feet, and inches. Unit Converters Convert between weight and mass units such as kilograms, grams, pounds, ounces, and stones. Unit Converters Convert between temperature units such as Celsius, Fahrenheit, and Kelvin in real-time. Unit Converters Convert between area units such as square meters, square miles, acres, and hectares. Unit Converters Convert between volume and liquid capacity units such as liters, gallons, and cubic meters. Unit Converters Convert between speed and velocity units such as mph, km/h, knots, and meters per second. Unit Converters Convert between pressure units such as pascals, bar, psi, atmosphere, and mmHg. Unit Converters Convert between energy and work units such as joules, calories, and kilowatt-hours. Unit Converters Convert between fuel efficiency units such as MPG, L/100km, and kilometers per liter. Unit Converters Convert between angular measurement units such as degrees, radians, and gradians. Unit Converters Convert between data storage units such as bits, bytes, megabytes, and gigabytes (binary/decimal). Date & Time Calculate your exact age in years, months, and days based on your birthdate. Date & Time Find the exact number of days, weeks, months, and years between two dates. Date & Time Calculate the number of business working days between two dates, excluding weekends and custom holidays. Date & Time Convert dates and times between different world time zones in real-time. Date & Time Set up a custom online countdown timer for events and dates. Date & Time A clean online stopwatch with lap and split time tracking capabilities. Date & Time Generate and print custom monthly or yearly calendars for any year. Date & Time Identify the ISO week number and start/end dates for any calendar date. Date & Time Check if a specific calendar year is a leap year and read leap rules. Color Tools Select colors and inspect matching HEX, RGB, HSL, HSV, and CMYK parameters. Color Tools Convert HEX color values to RGB or RGBA notations online. Color Tools Convert RGB or RGBA color values to standard hexadecimal strings. Color Tools Translate hexadecimal colors to HSL parameters (hue, saturation, lightness). Color Tools Convert HSL parameter coordinates back to standard HEX colors. Color Tools Generate harmonized color palettes based on monochromatic, triadic, or analogous relationships. Color Tools Design linear and radial gradients with customizable stops and CSS outputs. Color Tools Create advanced CSS background gradients with customizable positions and stops. Color Tools Audit foreground/background color combinations against WCAG 2.1 accessibility benchmarks. Color Tools Simulate how colors and uploaded images appear under different color vision deficiencies. Color Tools Generate standard Tailwind CSS color scales (50 to 955) from a single custom color. Password Tools Generate secure, cryptographically random passwords with custom parameters. Password Tools Assess password security, entropy, and estimate crack times using zxcvbn. Password Tools Simultaneously generate MD5, SHA-1, SHA-256, SHA-512, and bcrypt hashes. Password Tools Generate MD5 checksum hashes for strings and payloads. Password Tools Generate SHA-1 cryptographic hashes for verification checkups. Password Tools Generate secure SHA-256 checksum strings client-side. Password Tools Generate high-entropy SHA-512 hashes online. Password Tools Create bcrypt hashes using customizable salt rounds. Password Tools Compare two hash strings or verify a plaintext string against a hash. Password Tools Generate lists of secure random strings with customizable alphabet sets. Text Tools Count words, characters, sentences, paragraphs, read time, and character densities. Text Tools Count character lengths with and without spaces. Text Tools Count sentence occurrences in text blocks. Text Tools Count paragraph blocks in text bodies. Text Tools Reverse character order sequences in text inputs. Text Tools Filter out duplicate lines from multiline text lists. Text Tools Sort lines of text alphabetically or numerically. Text Tools Randomly shuffle the line ordering of multiline text inputs. Text Tools Generate randomized readable sentence blocks. Text Tools Generate custom standard placeholder Lorem Ipsum paragraphs. Text Tools Convert text between UPPERCASE, lowercase, camelCase, snake_case, or Title Case. Text Tools Clean and parse parameters, trailing slashes, and symbols from URL slugs. Text Tools Compare two text bodies side-by-side to review exact matches. Text Tools Visualize word and line additions/deletions between two text versions. Text Tools Strip double spaces, leading/trailing spaces, and empty lines. Text Tools Prepend index numbers to multiline text inputs. Text Tools Find and replace substring matches or regular expressions. Text Tools Capitalize letters of words or sentences. Text Tools Reverse word order coordinates inside sentences.

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Regex Tester & Replacement Studio

Test regular expressions in real-time with visual match highlighting, capture group inspection, regex replacement, and common pattern presets.

Free Online Regex Tester & Replacement Tool

Test JavaScript and PCRE-compatible regular expressions against sample text. View real-time color match highlights, inspect capture groups with index positions, test string replacements using $1 references, and toggle regex flags (g, i, m, s, u).

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Ready to test regex.

What is a Regular Expression (Regex)?

A Regular Expression (Regex) is a sequence of characters that forms a search pattern. It is used in software development for string matching, data validation (e.g. validating emails or credit cards), text extraction, and automated search-and-replace operations.

How to use it

  1. Enter your regular expression pattern inside the /pattern/ field.
  2. Toggle regex flags (g for global search, i for case-insensitive matching).
  3. Paste test text to see instant match results and capture group tables.
  4. Switch to String Replace Mode to test pattern replacement templates with $1, $2 capture group references.

Frequently Asked Questions (FAQ)

What do regex flags (g, i, m, s, u) mean?

g (global) finds all matches instead of stopping after the first. i (case-insensitive) ignores letter casing. m (multiline) treats anchors ^ and $ as line beginnings/ends. s (dotall) allows . to match newlines. u enables full Unicode matching.

How do capture group replacements work?

In Replace Mode, use $1 for the first parenthesized group (...), $2 for the second group, and $0 for the entire matched string.

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