Developer Utilities
Small developer utilities that save a trip to a random website. Encode and decode Base64, explain a regex, build UTM links, generate QR codes and vCards, and more — the everyday helpers. Free in your browser, and available by API when you need them in a script.
ISO 7064 check digit
With MOD 11-2, the code 0794 gets the check character 0, so the full identifier is 07940. Add the check character to a numeric or alphanumeric code, or verify a…
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Wabun Morse code translator
こんにちは becomes ---- .-.-. -.-. ..-. -...: each kana mora gets its Wabun telegraph code, with spaces between letters and a slash between words.
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JMBG check digit
The twelve digits 180198071000 get the check digit 5, giving the full JMBG 1801980710005. Complete or check the unique master citizen number used in Serbia…
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JavaScript string escaper
Text with quotes and a line break, such as Hello "world" over two lines, becomes Hello \"world\"\nline 2, ready to paste between double quotes.
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JSON string escaper
Say "hello", a line break and world become Say \"hello\"\nworld: three escapes, ready to paste between double quotes without breaking the document around it.
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Iceland kennitala check digit
Enter the date and serial 12017433 and get the kennitala check digit 9, worked out with the weighted modulus-eleven rule of the Icelandic National Registry.
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Keyboard coordinate cipher
On a US QWERTY keyboard, hello becomes 2,6 1,3 2,9 2,9 1,9: each letter is named by its row counted from the top and its column counted from the left.
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LaTeX escaper
In 10%_off, LaTeX would read the percent sign as the start of a comment and the underscore as a subscript; escaped as 10\%\_off, both print as written.
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LDAP DN escaper
Smith, John becomes Smith\, John, so the comma stays part of the name instead of splitting the distinguished name.
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Longitudinal redundancy check (LRC)
The nine bytes of 123456789 give the check byte 31 in hexadecimal, 49 in decimal: each byte is combined with exclusive or (XOR), the simplest block parity…
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Luhn mod-10 check digit
For 7992739871 the Luhn check digit is 3, giving 79927398713: the same mod-10 rule payment cards use, applied to any string of digits such as loyalty IDs…
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Luhn mod N check character
With the alphabet abcdef, the code abcdef gets the check character e, so it becomes abcdefe. Luhn mod N runs the classic double-and-sum rule in base N, for…
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Mailto link builder
Give support@example.com a subject and a body, and get a ready-to-paste mailto link where Hello from the web becomes Hello%20from%20the%20web and every space…
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Markdown escaper
In Use *stars* and _underscores_, each star and underscore gets a backslash, as in \*stars\*, so the words appear exactly as typed instead of turning bold or…
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Match Rating Approach codex
Smith becomes SMTH: the Match Rating Approach drops vowels after the first letter, merges doubled consonants and keeps at most six letters, so names that sound…
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Unicode bold text
Hello World 2026 becomes 𝐇𝐞𝐥𝐥𝐨 𝐖𝐨𝐫𝐥𝐝 𝟐𝟎𝟐𝟔: 14 letters and digits swapped for Unicode Mathematical Bold characters, so the style travels with the…
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Australia Medicare check digit
For the base digits 21234567 the Medicare check digit is 0: the eight digits are multiplied by 1, 3, 7, 9, 1, 3, 7 and 9, the products add up to 170, and 170…
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MEID check digit calculator
For the MEID body 6C4BFFC0000004 the check digit is 4, giving the fifteen-character 6C4BFFC00000044: the standard Luhn rule worked in base 16 over the hex…
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MIME B encoded-word
Hello café becomes =?UTF-8?B?SGVsbG8gY2Fmw6k=?=, an RFC 2047 encoded-word that carries the accent safely through mail headers such as Subject or From.
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ISO 7064 mod-11 check digit
For 079 the ISO 7064 MOD 11-2 check character is 4, giving 0794; when the result is ten, the check is written as X so every value has one printable symbol.
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ISO 7064 mod 97-10 check digits
For 123456 the ISO 7064 MOD 97-10 check digits are 76, giving 12345676: the same two-digit rule that protects IBAN check digits, applied to any code of letters…
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Unicode monospace text
Hello World 123 becomes 𝙷𝚎𝚕𝚕𝚘 𝚆𝚘𝚛𝚕𝚍 𝟷𝟸𝟹: 13 letters and digits swapped for Unicode Mathematical Monospace characters, giving a fixed-width…
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Morbit cipher
With the key 568931724, MORE BITS becomes 32379749578158: the message is written in Morse, read two symbols at a time, and each of the nine possible pairs is…
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MurmurHash3 hash calculator
Type Hello, world! and get c0363e43: the MurmurHash3 x86 32-bit hash of its 13 bytes with the default seed 0.
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Japan My Number check digit
For the eleven digits 12345678901 the Japanese My Number check digit is 6, giving the full 123456789016, worked out with the official weighted sum modulo 11.
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Myszkowski transposition cipher
With the key TOMATO, WEAREDISCOVEREDFLEEATONCE becomes ROFOACDTEDSEEEACWEIVRLENE, and the same key turns it back.
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Portuguese NIB check digits
For the body 0002 0123 12345678901 the check digits are 54, so the full NIB reads 0002.0123.12345678901.54.
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Spain NIE control letter
X1234567 gets the control letter L, so the full NIE is X1234567L. Type the prefix and seven digits to complete a foreign resident's number, or paste a whole NIE…
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Polish NIP check digit
The nine digits 526104082 get the check digit 8, giving the NIP 526-104-08-28. Enter nine digits to complete a Polish tax number, or all ten to catch a mistyped…
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NPI check digit
The base 123456789 gets the check digit 3, so the full NPI is 1234567893. Enter nine digits to complete a National Provider Identifier, or ten to confirm its…
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Chaldean numerology calculator
John comes out as 9 in Chaldean numerology: J is 1, O is 7, H and N are 5, a total of 18, and 1 plus 8 makes 9.
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Pythagorean numerology calculator
John Smith gives 8: its letters add up to 44, and 4 plus 4 is 8. Letters take the values 1 to 9 in alphabet order, starting again at J and at S, and the total…
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Numeronym generator
Internationalization becomes i18n: the first letter i, the 18 letters in between, and the last letter n.
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NYSIIS encoder
Bishop becomes BASAP in NYSIIS, a phonetic code that gives names spelled differently but pronounced alike the same key.
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Ook! encoder and decoder
Hi becomes a 1069-character Ook! program built only from Ook., Ook! and Ook? in fixed pairs, one pair for each Brainfuck command.
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Opish language translator
Hello becomes Hopeloplopo in Opish: every consonant gets op after it and the vowels stay as they are.
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Indian PAN card validator
AAAPL1234C is a valid PAN for an individual: five letters, four digits and a final letter, with P in fourth place meaning a person.
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Parity bit calculator
1011001 has four ones, so its even parity bit is 0 and its odd parity bit is 1; appending even parity gives 10110010.
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Sweden personnummer check digit
The nine digits 811228987, a birth date plus serial, get the Luhn check digit 4, giving the personnummer 8112289874.
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Phone keypad multi-tap encoder
HELLO becomes 44 33 555 555 666 on a classic phone keypad: press 4 twice for H, 3 twice for E and 5 three times for each L.
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Pigpen cipher
In Pigpen, H is the bottom cell of the plain grid and E its centre, while L and O sit in the dotted grid.
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Police phonetic alphabet
UNIT becomes Union Nora Ida Tom in the police phonetic alphabet, the Adam, Boy, Charlie list used by North American dispatch.
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Pollux cipher encoder and decoder
With the key .-xx.-x.-x, HI becomes 0470247: the message is first written in Morse, then each dot, dash and gap is replaced by a digit the key assigns to it.
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Porta cipher
With the passphrase PORTA, “Hello, World!” becomes “Oytub, Chjuq!”, and the same passphrase turns it back.
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Printf format escaper
“Progress: 50% complete” becomes “Progress: 50%% complete”, so printf prints the percent sign instead of reading it as a conversion.
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Q-code translator
QTH means station location and QSL means acknowledging receipt: paste ham radio Q-codes to read their meaning, or type a phrase such as low power to get QRP.
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Query string parser
name=Ada&city=New%20York&q=hello+world splits into three pairs, name Ada, city New York and q hello world.
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Q-encoding header encoder
Put accents into an email Subject or sender name safely: Hello café becomes =?UTF-8?Q?Hello_caf=C3=A9?=, and a pasted encoded-word decodes back to readable…
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Refined Soundex encoder
Robert becomes R9196: the first letter stays, each consonant sound becomes a digit from a finer table, and nothing is cut to four characters, so long surnames…
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Regex metacharacter escaper
Paste file.txt (v1.0+) and get file\.txt \(v1\.0\+\): every dot, bracket, plus sign and other regex operator gets a backslash, so the pattern matches your text…
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Poland REGON check digit
Type the base 12345678 and get check digit 5, so the full REGON is 123456785. It also validates complete 9- and 14-digit numbers, including the parent part…
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RFC 1751 S/KEY word encoder
The 64-bit key EB33 F77E E73D 4053 becomes TIDE ITCH SLOW REIN RULE MOT: six short English words that are easier to read aloud or copy by hand than hex, with…
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Czech rodné číslo check
Enter 7401040020 and see that it is valid: a man born on 4 January 1974, with the whole number divisible by 11.
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ROT8000 Unicode cipher
Hello becomes 聈聥聬聬聯: every character in the Basic Multilingual Plane, spaces, digits and any script included, jumps half the plane, and the same step brings the…
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ROT-N cipher
Choose any shift from 0 to 25: with 13, Hello, World! becomes Uryyb, Jbeyq!, with 3 you get the textbook Caesar cipher, and decoding moves each letter back by…
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RTF Unicode escaper
café becomes caf\u233?: plain ASCII stays readable, every other character turns into an RTF control word with a signed decimal and a fallback mark, and pasted…
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Ecuador RUC check digit
1710034065001 is valid: a natural person from province 17, check digit 5 in position ten and establishment 001.
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Running-key cipher
With the key passage It was the best of times, Attack at dawn becomes Impaud hx eeog: each letter is shifted by the next letter of a long text that never…
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Unicode sans-serif text
Hello123 becomes 𝖧𝖾𝗅𝗅𝗈𝟣𝟤𝟥: letters and digits switch to Unicode sans-serif characters that paste into names, captions and titles without any special…
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Unicode cursive script text
Hello becomes ℋℯ𝓁𝓁ℴ: each Latin letter turns into its Unicode cursive script form for names, bios and invitations, digits and punctuation stay as typed, and…
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