Tools · Vixyun · Tools & Content

JSON Formatter — Pretty Print, Minify, and What the Round Trip Rewrites

Paste JSON and it prints it back with your browser's own parser: pretty-printed, minified, keys sorted if you ask. It then lists every value the round trip rewrote - integers past 2^53, 1.0 and 1e3, -0, duplicate keys, reordered keys - and a failed parse comes back with the line and column.

Percentage Calculator — what percent of, increase or decrease by, percent change, reversing a discount

Four separate answers for the four questions people actually type: 87 out of 120 is what percent, 120 plus 15 percent, the percent change from 120 down to 102, and the original price when 240 is the 20%-off price. Live results, division by zero explained, float noise cleaned to 12 significant digits.

Calculator — expressions with brackets, powers, roots and percent

Type a whole expression and get the answer: brackets, × ÷, powers, square roots, logs, trig functions and percent signs (so 120 + 15% really gives 138). Use your keyboard or the on-screen keys. Parsing and maths happen on your device.

Word Counter — Three Numbers for One Text, and Two Ways to Split a Word

One text, three character counts: code units as they are stored, code points as they are numbered, grapheme clusters as a reader groups them. Words are counted twice too - by a pattern, and by this browser's own segmentation - and every span where the two come apart is listed. Chinese, Japanese and Korean text gets a word count from the segmenter; the pattern finds nothing in it. Nothing you type or paste is sent anywhere.

Base64 Text Encoder / Decoder — UTF-8 safe, so Chinese and emoji survive

Encode text to Base64 or decode it back. Works on UTF-8 bytes, so Chinese and emoji do not throw the InvalidCharacterError you get from btoa. URL-safe output, optional = padding, byte counts and inflation ratio. Your input never leaves this device.

URL Encoder / Decoder with Query-String Breakdown

Split a link into scheme, host, port, path, query and fragment (international domains come out as punycode), or percent-encode and decode any text with a count of every escape. Everything runs locally in your browser.

Unix timestamp to date and time — 10-digit seconds, 13-digit milliseconds, local and UTC

Paste a 10-digit second or 13-digit millisecond timestamp and read off the local time, the UTC time and both ISO 8601 spellings; or pick a date and time and get its seconds and milliseconds back. How the digit count decides the unit, and where the famous 8-hour offset comes from, is explained below. Everything converts on your device.

Case Converter for Identifier Names — camelCase, snake_case, kebab-case and 4 More

Turn a name, or a whole column of names, into camelCase, PascalCase, snake_case, CONSTANT_CASE, kebab-case, Title Case and sentence case, and show which words it split the input into. Everything runs locally in your browser.

Color Format Converter & WCAG Contrast Checker (HEX · rgb · hsl)

Convert one color between HEX, rgb() and hsl() and read its WCAG relative luminance, then test a foreground/background pair against all five WCAG 2.1 contrast thresholds and get the smallest fix when it fails. Everything is computed in your browser.

Image Compressor - What Each Format Actually Costs in Bytes

Measures compression instead of promising it: real bytes out for every format your browser encodes, a quality search when you must fit a target size, and what the metadata and transparency lose.

Text Diff — Compare Two Blocks of Text Line by Line

Diff two blocks of text line by line: an exact longest-common-subsequence edit script listing added, removed and unchanged lines, a similarity percentage, and optional trailing-whitespace and case ignoring. Everything runs in your browser and what you paste never leaves this device.

Regex Tester with Match Positions, Capture Groups and Replace Preview

Type a pattern and some text and see every match with its position, its raw text and each capture group — null distinguished from empty — plus the result of a $& / $1 / $ replacement. Everything runs locally in your browser.

Days Between Two Dates — the Gap in Days, Weeks, Months and Working Days

Pick two dates and the gap comes out every way you might need it: calendar days, the same span written as years-months-days, weeks, whole months, and how many of those days are weekdays. Optional clock times turn it into an hours figure.

Age Calculator — Full Years, Leftover Months and Days, and the Next Birthday

Type a birthday and read the age the way people actually say it: full years plus the leftover months and days, how many days that adds up to, how long until the next birthday, which weekday the birth date fell on, and the zodiac sign of that year.

Password Generator with Real Randomness — and an Honest Strength Read

Draw passwords from the browser's cryptographic random numbers with rejection sampling, so no character is quietly favoured, then read the bits, the average number of guesses and what those numbers do not say about a password you typed yourself. Everything happens in this tab — what you type never leaves this device.

UUID Generator — v4, v7 and v1 Built From Your Browser's Own Random Bytes, With the Fields Read Back Out

Make v4, v7 or v1 UUIDs in your browser, from crypto.getRandomValues, and have every value taken apart again in front of you: the version nibble, the variant bits, the 48-bit or 60-bit instant carried inside a v7 or v1, the count of bits that are actually random. Write them out dashed, undashed, in braces or as urn:uuid:, in either alphabet. Put a list side by side with the ones your own browser's crypto.randomUUID() produces and compare the two. Paste UUIDs back in to be read, including the ones your library wrote in the other byte order. Nothing you generate, paste or save is sent anywhere.

QR Code Generator - The Symbol Built Under Your Hands, Module by Module

Mode chosen by bit cost, version sized by arithmetic, Reed-Solomon check words computed in GF(256), all eight masks scored - and then the finished symbol is read back out of its own modules to check the symbol that came out.

Number to Chinese Words — spoken reading and RMB capital amount (大写)

One number in, both Chinese spellings out: the plain reading used in body text (一千二百三十四点五) and the anti-tampering capital form invoices and bank wires insist on (壹仟贰佰叁拾肆元伍角). Accepts negatives, decimals and thousands commas, rounds money to the fen, merges runs of zeros. Your input never leaves this device.

Storage Unit Converter — Bytes, KB and KiB Side by Side, Plus the Real Size of a Disk

Type a size such as 1.5 GiB, 500MB or 8e3 KB and it prints the exact byte count next to every decimal and binary unit, shows how a 1 TB drive ends up as 931 GiB, converts a rate like 100 Mbps into how long the download takes, and compares the amount with floppy disks, CDs, DVDs and Blu-ray discs. Everything runs locally in your browser.

CSV to JSON Converter (and Back) — Quoted Cells, Embedded Newlines, Ragged Rows

Paste CSV and get an array of objects, or paste JSON and get text back that a spreadsheet will open. The delimiter, the header row and the ragged rows are all reported instead of guessed at, and every step is a loop in plain JavaScript, with no server in the middle — what you paste never leaves this device.

Image to Base64 — A Data URL, an img Tag, or the Raw String, With the Real Size Cost

Pick a picture from this device and get back exactly the form you need: a data URL, the raw base64 string, an image tag, a CSS background rule, or a JSON value. The type comes from the file's own magic bytes rather than its extension, so a .jpg that is really a PNG says so. Every output is measured - bytes in, characters out, the size change, and a table of which destinations that string can actually be pasted into. Paste base64 back in to decode it, check the padding, see the picture and save it as a file. Nothing you pick leaves this device.

Text Dedupe and Sort by Line — Remove Duplicates, Empty Lines and Sort Naturally

Paste a column of text and it drops duplicate lines, strips leading and trailing whitespace, removes empty lines, and sorts lexicographically, by character count or in natural order so item2 comes before item10. It also tells you exactly which lines were merged. Everything runs locally in your browser.

Random Number Picker — Unbiased Draws, Name Lotteries, and a Seed You Can Re-run

Whole numbers, decimals, or names you paste in — drawn from the browser's cryptographic generator using a mask-and-reject step instead of a modulo, so every outcome really has the same chance. Draws can be without repetition, a list can be split into even groups, and a seed mode makes the whole draw reproducible so you can show somebody the result was picked once, not re-rolled until it looked good. There is a measured side-by-side of the modulo bias. Nothing you type leaves this device.

Markdown to HTML - Every Block Named, Every Refusal Recorded

CommonMark block structure resolved by column arithmetic, emphasis by the rule of three, and four tables underneath: which block each run of lines became and why, which constructs were declined rather than interpreted, and your own browser's HTML parser checking the markup that came out. Nothing you type leaves this device.

HTML to Markdown - Every Tag Traced, Every Refusal Recorded

Paste markup, get markdown back - with the whole path in print: the tokeniser that read your tags the way your browser reads them, what each element became and why, every character that had to be escaped, every construct that was declined, and a differential run against your own browser's HTML parser at the bottom. Nothing you paste leaves this device.

HTML Entity Escape and Unescape — & < Numeric References and the Browser's Lenient Rules

Turn plain text into HTML-safe markup (& < > quotes, plus optional numeric references for Chinese and emoji), or decode entity references back to text: a 187-name table, the legacy entities that never needed a semicolon, the Windows-1252 numeric range and the surrogate rules, all matching what the browser's own parser produces.

List Converter — Lines, Commas, Arrays and SQL IN From One Paste

Paste any messy list and get it back as plain lines, comma or semicolon separated text, a Markdown bullet list, a JavaScript array, JSON, an SQL IN list or HTML items — with trimming, empty items dropped, duplicates removed and natural sorting applied on the way. Everything runs locally in your browser.

Date Add and Subtract — a Start Date Plus a Duration Gives the Due Date

Add or take away years, months, weeks, days, hours and minutes from a date and see the result with its weekday, how far it sits from today, and how the month-end and leap-year rounding was handled.

Hash and Checksum Calculator — MD5, SHA-1, SHA-256, SHA-384, SHA-512, CRC32 and Adler32 for text or a file

Type text or pick a file and get every digest at once: MD5, SHA-1, SHA-256, SHA-384 and SHA-512 from the browser's own crypto, plus hand-written CRC32 and Adler32. Paste a published checksum and the line that matches is named. Nothing you type or open leaves this device.

Loan Payment Calculator — monthly installment, total interest, year-by-year amortization

Enter the loan amount, annual rate and term to get the equal-payment monthly installment, total interest, an equal-principal comparison, and a year-by-year breakdown of how much you are actually paying off. Runs entirely in your browser.

Daily Rate to Annual Salary — working days, hourly equivalent, and what rate you actually need

Turn a day rate into an annual, monthly and hourly figure using the days you really work, then work backwards from a target income to the daily rate you need and how many days it would take. Everything is calculated in your browser.

Savings Goal Calculator — how long to reach my target

Enter a savings target, what you already have, your monthly deposit and an interest rate. Get the month you reach it, how much came from interest, and what you would need to save monthly to finish in 3, 5 or 10 years. Runs entirely in your browser.

Image EXIF Reader — Open a Photo and See What the Camera Wrote

Pick a JPEG, PNG, WebP or TIFF file and read the metadata the camera left in it: model, exposure, orientation, timestamps and GPS coordinates, decoded byte by byte in your browser from the file on your disk — the file never leaves this device.

Timezone Meeting Planner — One Instant, Every Attendee's Clock, and the Hours That Actually Work

Type a date and a clock reading, say which zone that reading belongs to, then pick up to six cities. Each one gets its local time, weekday, UTC offset, whether the day rolls over, and whether that hour falls inside your working window. Nudge the instant by an hour and a 24-hour scan lists every slot ranked by how many people would be at work. Clocks that skip or repeat an hour around a daylight-saving change are reported as they are, and nothing you type leaves this device.

JSON to TypeScript Converter — Interfaces, Unions and Optional Keys From Real Samples

Paste a JSON response and get TypeScript declarations for it: nested interfaces, array element types, a union where the records really do differ, a question mark on keys some objects lack, and quoted names for keys that are not identifiers. Every caveat the sample leaves open is listed instead of guessed away, and what you paste never leaves this device.

Cron Expression Parser — What a Crontab Line Means and When It Next Fires

Paste a crontab line and it splits the five or six fields, lists every value each field really matches, explains the day-or-week rule, and computes the next upcoming run times from this machine's clock. No server is contacted and nothing you type leaves this device.

JWT Decoder — Read the Header and Payload and What exp Actually Says

Paste a JSON Web Token and it splits the three base64url segments, prints the header and payload as formatted JSON, and turns iat, nbf and exp into real dates with a plain answer to whether the token is still inside its own validity window. No key is asked for and no signature is checked. Everything runs locally in your browser.

HTTP Status Code Lookup — What 404, 502 and 429 Actually Mean

Enter a status code, or paste a response line and a log fragment, and get what the number promises, what the browser does next, and where to look first — for 200 and 204, for 301, 302, 303, 307 and 308, for the whole 4xx family and for 502 versus 504. Includes whether repeating the request is safe. Everything runs locally in your browser.

IPv4 Subnet Calculator — CIDR breakdown & the smallest prefix that fits N hosts

Paste an IP with a prefix (like 192.168.1.0/24) to get the network address, usable host range, broadcast, netmask, wildcard and an IANA-range classification, or ask how large a prefix you need for a given host count. Runs entirely in your browser.

Base Converter - Every Base from Two to Thirty-Six, One Digit at a Time

Convert any integer or decimal fraction between base 2 and base 36 and read the work: the digit-by-digit ledger, which bases the number ends in and which repeat forever, the bytes at 8, 16, 32 and 64 bits in both endians, and a differential run against your own browser's Number, parseInt, BigInt and DataView at the bottom - with the size of every difference printed as a number. Nothing you type leaves this device.

Character Codes - Every Byte, Every Cluster, Every Rule Written Down

Paste any text and read it back as code points, UTF-8 and UTF-16 bytes, HTML character references, percent-encoding, a CSS identifier and a JavaScript string literal - plus the way it splits into the clusters your browser draws as one character, the exact rules behind that split, what gets declined rather than guessed, and a differential run against your own browser's encoder, segmenter and parser at the bottom. Nothing you paste leaves this device.

Contrast Checker - Two Colours, the Exact Ratio, and Every Rounding That Gets You There

Paste a foreground and a background as hex, rgb(), hsl(), hwb(), a CSS name or a wide-gamut function and read the WCAG 2.1 and 2.2 verdicts with the arithmetic shown: the 8-bit channels computed three ways, the layer stack a translucent colour really paints, the smallest lightness or opacity move that reaches the line with the steps counted, a palette matrix over every pair you paste, and a differential run against your own browser's colour parser, canvas and computed styles at the bottom. Nothing you type leaves this device.

Text Encoding Repair - What These Bytes Actually Say, and What Can Still Be Given Back

Give it a file and it reads the bytes: the mark at the front, whether the whole run is legal UTF-8 and if not exactly where it breaks, whether the pairs walk as GBK, Big5, EUC-KR or Shift_JIS, and what your own browser's decoder makes of them. Paste a screen of mojibake and it tells you which accidents are reversible and which lost the data. Hand back readable text, as UTF-8 with or without the BOM, or byte for byte as it came in. Nothing you pick leaves this device.

EAN Barcode Generator - The Check Digit, the Ten Patterns, and Every Module It Paints

Type or paste an EAN-13, EAN-8 or UPC-A number and build the symbol one module at a time: the weighted sum behind the check digit with every product listed, the ten seven-module patterns the three code sets are derived from, a part-by-part table of guards and digits, quiet-zone and millimetre arithmetic, and a read-back that measures the painted bars and the pixels your own browser rasterised before it agrees the number is still in there. Nothing you type leaves this device.