⚙️ Useful Utilities

helps find differences between any texts

quickly converts the case of any string to the desired format

turns text typed with the wrong keyboard layout back into readable text

placeholder text generator for layouts and prototypes

count characters, words, sentences, lines, and reading time

whole-text and per-line entropy, high-entropy secret line detection

live Markdown preview in real time

convert Markdown to Confluence Wiki Markup and back

Cyrillic to Latin: ICAO passport scheme, GOST 7.79-2000, and SEO slugs for URLs

a catalog of useful GitHub projects with stars, authors, tags, languages, and detailed repository pages

complete V.I. Dahl dictionary: 44,942 entries, search across headwords and definitions

modern explanations, word forms, and links across Dahl and Wiktionary

English word explanations, pronunciations, forms, translations, and synonyms from Wiktionary

format, minify, and validate JSON

compress JSON to one line without losing large integers or duplicate keys

pretty-print and minify SQL queries, several dialects

a reference of every HTTP status with clear explanations and search: 200, 301 vs 302, 404, 418, 429...

builds meta tags, Open Graph and Twitter Card with a live social card preview

builds a .gitignore for your stack from ready templates: Node, Python, Laravel, Go and more

escape and unescape for JSON, JS, SQL, CSV, regex, shell and HTML

Mermaid diagram editor with live preview: flowcharts, sequence, class, ER, Gantt, mindmap. Export as SVG/PNG and share link

live mock APIs with projects, endpoints, response variants, delays, templates and request logs

temporary endpoint for receiving webhook requests and inspecting headers, query, and body

test regular expressions with match highlighting

generate UUID v4, bulk generation

generate MD5, SHA-1, SHA-256, SHA-512 hashes

decode and analyze JWT tokens

visual Elasticsearch Query DSL builder: bool queries, filters, sorting, aggregations, mapping-aware hints, and validation

parse cron expressions into human-readable format with next run times

visual cron expression builder with presets and live preview

chmod permissions calculator (755 ↔ rwxr-xr-x) with interactive checkboxes

generate QR codes with dot style, color, logo customization and PNG/SVG download

compare two JSON documents or validate against JSON Schema with optional value checks

validate JSON structure and types against a schema with a complete guide

powerful diff for two CSV files: match by key or row, filters, stats, supports large files

area of a circle, triangle, trapezoid, and other shapes — with the formula, substitution, and explanation

motion problems with explanations: the formula, unit conversion (km/h ↔ m/s), and substitution

A mechanical model of an inline four: pistons, camshaft and valves in motion, with a crank you can turn

molar mass from a chemical formula with a per-element breakdown: H2SO4, Ca(OH)2, hydrates

An analytical calculator on an infinite canvas: step-by-step solutions, graphs, matrices, geometry

solve quadratic equations with step-by-step explanations: discriminant, root formula, Vieta check

add, subtract, multiply, and divide fractions with step-by-step solutions: common denominator, reducing, mixed numbers

percent of a number, percentage change, and a number from its percent — with formulas and explanations

greatest common divisor and least common multiple with explanations: Euclidean algorithm step by step and prime factorization

aₙ/bₙ coefficients, partial sums, textbook functions, and pointwise convergence visualization

RREF, determinant, inverse matrix, and Ax=b solving with exact fractions and row steps

Compress PDF online directly in your browser. Best for scans and image-heavy PDFs: choose quality and DPI, then download a smaller file.

Merge multiple PDF files into one document online. Files are processed locally in your browser and are not sent to a server.

Split a PDF into separate pages online. Select a page range and download a ZIP with individual PDF files.

Extract selected pages from a PDF into a new document online. Ranges like 1-3, 7, 10-12 are supported.

Rotate all PDF pages or a selected range by 90, 180, or 270 degrees online directly in your browser.

View and edit PDF metadata online: title, author, subject, keywords, creator, producer, and document dates. Processing runs in your browser.

Remove PDF metadata online: rebuild pages into a new document without original title, author, subject, and keywords fields.

Convert PDF to Word DOCX online. Server-side pdf2docx conversion with temporary file handling and automatic cleanup.

Convert Word DOC/DOCX to PDF online through LibreOffice. DOC, DOCX, ODT, RTF, and TXT are supported with temporary server-side processing.

encode and decode text to/from Base64

convert colors between HEX, RGB, and HSL

HSL color wheel with palette generator across six classic schemes (complementary, triadic, etc.) and export options

crop, resize, compress, strip EXIF, and convert PNG/JPEG/WebP/AVIF directly in the browser

shows camera, lens, date, GPS, and other image metadata directly in the browser

convert numbers between BIN, OCT, DEC, and HEX

temperature, length, area, volume, mass, speed, pressure, energy, and hundreds of conversion directions

CBR, NBK, ECB rates and crypto: instant conversion with charts

a utility for working with UNIX Timestamp. Converts timestamps to a readable format or converts date and time into a number

convert a page address or text into a readable format or encode special characters

encode and decode HTML entities (& ↔ &)

calculate the difference between two dates in years, months, days, hours, minutes, and seconds

convert between CSV and JSON formats with delimiter settings

convert between YAML and JSON formats with indent settings

get information about your or any other IP address: country, city, approximate coordinates, and timezone

compute range, mask, broadcast, host count from CIDR and split a network into subnets. IPv4 and IPv6

test how any deeplinks work for your applications

check website availability, HTTP code, response time, SSL, and IP address

look up A, AAAA, CNAME, MX, TXT, NS, SOA, and CAA records for a domain

inspect certificate validity, issuer, SAN names, expiration, fingerprint, and TLS details

analyze any page: title, meta tags, Open Graph, Twitter Cards, schema.org, headings, links, robots.txt, and an overall SEO score

generate secure passwords with customizable settings

real-time earthquakes on a map: search, sensitivity zones and "I felt it" reports

ISS, Tiangong and Hubble live on a map with ground track, day-night terminator and pass predictions for your city

Kp index, geomagnetic storms, solar flares, solar wind and the aurora oval with a visibility estimate for your latitude

asteroid close approaches for the next 60 days: distance in lunar distances, size and speed from NASA/JPL data

active fire hotspots from the last 24 hours from NASA satellites on a map, the strongest fires and nearest cities

volcanoes with new and ongoing activity this week from the Smithsonian / USGS weekly volcanic activity report

live air-traffic map from ADS-B and OpenSky: flights, routes, tracks, search by flight number, airframe or airport, METAR/TAF weather and NOTAMs

interactive TUI tool for analyzing and cleaning disk space from the terminal

a desktop app that builds a full course on any topic through your Claude Code or Codex subscription

a Claude Code mod that decrypts HTTPS, HTTP/2, gRPC, WebSockets and SSE from the browser, iOS and Android, and lets Claude read, replay and mock the traffic