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.
Double columnar transposition
With the keys ZEBRAS and then STRIPE, WEAREDISCOVEREDFLEEATONCE becomes CAEENSOIAEDRLEFWEDREEVTOC: two keyword grids rearrange the text one after the other.
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Brazil CPF check digits
Enter the nine digits 529982247 and get check digits 25, so the full CPF is 52998224725; or paste eleven digits to see whether the last two match.
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Denmark CPR check
Enter 0707610018 and see a valid Danish CPR number for a woman born on 7 July 1961, with the mod-11 control passing.
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CRC-16 Kermit checksum
The nine characters 123456789 give the CRC-16 Kermit value 2189, the reference result for this profile, so you can tell at once whether a device or library…
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CRC-16 Modbus checksum
A Modbus RTU request reading ten holding registers from register 0 of device 1 gets the CRC CDC5, sent as C5 CD.
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CRC-16 XMODEM checksum
The nine characters 123456789 give the CRC-16/XMODEM value 31c3, or 12739 in decimal, the documented check result for the zero-start CCITT profile used in…
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CRC-32 checksum
The nine characters 123456789 give the CRC-32 value cbf43926, the same check ZIP archives and PNG images use, so you can compare your result with any standard…
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CRC-64 checksum
The nine characters 123456789 give the CRC-64/ECMA-182 value 6C40DF5F0B497347, the reference check for this profile, so a library that returns anything else is…
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CRC-8 checksum calculator
The nine characters 123456789 give the CRC-8 value f4, or 244 in decimal, the documented check for the SMBus profile with polynomial 07, so you can verify a bus…
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CSV field quoter
The cell He said "Hi", friend becomes "He said ""Hi"", friend": wrapped in double quotes with each inner quote doubled, as RFC 4180 requires, so commas and…
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Argentine CUIT/CUIL check digit
Enter 20-12345678 and get check digit 6, so the full CUIT is 20-12345678-6; type 20-12345678-7 instead and validation fails.
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Mexico CURP check digit
Enter HEGG560427MVZRRL0 and get check digit 4, so the full CURP is HEGG560427MVZRRL04; or paste all 18 characters to see whether the last digit matches.
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CUSIP check digit calculator
Enter the eight-character body of a CUSIP and get its ninth character: 03783310 gets check digit 0 and becomes 037833100.
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Dancing Men cipher
Turn plain letters into the stick figures of Conan Doyle's Dancing Men and back again: HI becomes two figure descriptions, one per letter, and anything that is…
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Digrafid cipher
Run Delastelle's Digrafid cipher with two keywords: DCODE with the keys KEYWORD and SECRET and a period of 3 becomes LTYDK#, and the same keys and period bring…
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djb2 hash calculator
Paste a word and get Bernstein's djb2 fingerprint: hello gives 0f923099, or 261238937 as a plain number, the same result textbook code produces.
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DNA base encoder
Write a word and see it as DNA letters: Hi becomes CAGACGGC, four bases per byte, because every pair of bits maps to A, C, G or T.
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Spanish DNI/NIF letter calculator
Type the eight digits of a Spanish DNI and get its control letter: 12345678 leaves a remainder of 14 when divided by 23, so the letter is Z and the full number…
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Double Metaphone encoder
Type a name and get two sound-alike keys: Smith gives SM0 as its main code and XMT as the alternate, so records spelled differently but pronounced alike can be…
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Dutch spelling alphabet
Spell any code the Dutch way over the phone: SOS becomes Simon Otto Simon, and every letter from Anna for A to Zacharias for Z, plus the number words Nul to…
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Dvorak QWERTY converter
Recover text typed with the wrong US keyboard layout: Hello typed on QWERTY keys while the computer expected Dvorak comes out as D.nnr, and one swap brings it…
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EAN-13 check digit calculator
Enter the twelve product digits and get the thirteenth: 400638133393 gets check digit 1 and prints as 4006381333931.
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EBCDIC encoder
Turn text into IBM mainframe bytes and back: Hello becomes c8 85 93 93 96 on code page 037, and a pasted hex dump from a COBOL file or trace comes back as…
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Ecoji emoji encoder
Wrap a short message in emojis that survive any chat window: Hello, Ecoji! is 13 bytes and becomes 12 emojis, and pasting them back returns the exact text…
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Bulgarian EGN check digit
Enter the first nine digits of a Bulgarian EGN and get the tenth: 752316926 gets check digit 3 and becomes 7523169263, shown as 752316-926-3.
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US EIN format validator
Check a US EIN before it goes on a W-9 or vendor record: 12-3456789 has nine digits, the hyphen after the prefix and the prefix 12, which the IRS Andover campus…
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HTML named to numeric entities
Switch HTML entities between names and numbers: © becomes © and — becomes —, so markup passes through XML parsers and email gateways that…
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Fibonacci coding (Zeckendorf)
Write any positive whole number as a Fibonacci code: 6 is 5 + 1, so it becomes 10011, and every code ends in 11 so it can be spotted in a stream without a…
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Fletcher-32 checksum
Get a quick checksum that notices word order: 123456789 gives the Fletcher-32 value df09d509, and swapping characters usually changes it.
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Norwegian fødselsnummer check digits
Enter the first nine digits of a Norwegian fødselsnummer and get both control digits: 010190000 gets 8 and 3 and becomes 01019000083.
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FNV-1 hash calculator
Hash text the original Fowler–Noll–Vo way, multiplying before mixing in each byte: foobar gives 31f0b262 at 32 bits, the value reference tables list for FNV-1…
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FNV-1a hash
Get the FNV-1a fingerprint of any text, mixing in each byte before multiplying: foobar gives bf9cf968 at 32 bits, or sixteen hex digits at 64 bits, a stable tag…
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Fractionated Morse
Encrypt with Fractionated Morse and a keyword: COME TO THE EAST with the key GERMANY becomes FBKKCOKWGYXSQB, because the message is turned into Morse, cut into…
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Unicode Fraktur text
Turn plain letters into Unicode blackletter that keeps its gothic look wherever you paste it: Hello Fraktur becomes ℌ𝔢𝔩𝔩𝔬 𝔉𝔯𝔞𝔨𝔱𝔲𝔯, while digits…
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French spelling alphabet
Spell any name or code the French way over the phone: PARIS becomes Pierre Anatole Raoul Irma Suzanne, using the classic table from Anatole for A to Zoé for Z…
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English gematria calculator
Score any word or phrase with English gematria, where each letter is worth six times its place in the alphabet: KIT is 66 + 54 + 120, a total of 240.
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Hebrew gematria calculator
Type a Hebrew word and get its gematria in the standard system: שלום scores 300 + 30 + 6 + 40, a total of 376, with each letter's value listed in reading order.
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Ordinal gematria calculator
Add up a word with ordinal gematria, where every letter counts as its place in the alphabet: KIT is 11 + 9 + 20, a total of 40, which reduces to the single…
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Gibberish language translator
Hello becomes Hidellido and cat becomes cidat: this translator slides the syllable id in front of every vowel, or removes it to recover the original words…
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Grandpré cipher
With the keyword rows CODE, ABLE, FISH and TRAP, the word CAT encrypts to 112141: each letter becomes its row and column number on the grid you build.
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Turning grille cipher
ATTACKATDAWN on a 4-by-4 grille becomes ATTCXAKAXXDTXAWN: letters go through the mask's holes, the mask turns a quarter turn four times, and the full square is…
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India GSTIN check digit
For the body 27AAPFU0939F1Z the check character is V, giving the full GSTIN 27AAPFU0939F1ZV. Calculate that last character for a form or an import, or check a…
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GTIN-14 check digit
Enter the thirteen digits 1001234567890 and get check digit 2, for the full case code 10012345678902.
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Hex dump viewer
Hello World! becomes one dump line starting at offset 00000000, with its 12 bytes in hex and the readable text in a side column, then a closing 0000000c.
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Hill cipher 2×2
With the key numbers 3, 3, 2 and 5, HELP encrypts to HIAT: each pair of letters is multiplied by the key matrix modulo 26.
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Hill cipher 3×3
With the key 6,24,1,13,16,10,20,17,15, the word ACT encrypts to POH: each block of three letters is multiplied by the key matrix modulo 26, so every output…
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Hong Kong ID check digit
The body A123456 gets the check digit 3, so the full Hong Kong ID reads A123456(3). Calculate that last character, or check a full number before saving a…
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Homoglyph text converter
Hello World becomes Неⅼⅼо Ԝо𝗋ⅼԁ: it still reads the same, but 10 of its characters are now Cyrillic, Greek or other look-alikes.
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Decimal HTML entities converter
Hi becomes Hi: every character, including spaces, accents and emoji, is written as its decimal code point between &# and a semicolon.
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Named HTML entities encoder and decoder
A & B © becomes A & B ©: every character with a standard name, from angle brackets to the trademark sign, is written by that name.
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IBAN check digit generator
Country DE, bank code 37040044 and account 0532013000 give check digits 89 and the IBAN DE89370400440532013000.
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IDNA domain encoder
münchen.example.com becomes xn--mnchen-3ya.example.com: each label with accents or another script gets its xn-- form, while plain ASCII labels stay as they are.
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IMEI check digit
The fourteen digits 49015420323751 get the check digit 8, giving the full IMEI 490154203237518. Complete a device number for a label or database, or check a…
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Intel HEX encoder
Address 256, type 0 and sixteen data bytes become the record :10010000214601360121470136007EFE09D2190140, with checksum 40 worked out for you.
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Internet checksum (RFC 1071)
The word hello gives the Internet checksum bc2d: its 5 bytes are paired into 16-bit words, added with carries folded back, and the sum is inverted.
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ISBN-10 check digit
The nine digits 030640615 get the check digit 2, so the full ISBN-10 is 0306406152. Complete a ten-character code, or check one from an old catalog, invoice or…
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ISBN-13 check digit
The twelve digits 978030640615 get the check digit 7, giving the full ISBN-13 code 9780306406157. Finish a book number before printing a barcode, or check a…
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ISBN-10 to ISBN-13 converter
The ISBN-10 code 0306406152 becomes the ISBN-13 code 9780306406157: the prefix 978 is added and the check digit is recalculated, from 2 to 7.
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ISIN check digit
For the body US037833100 the check digit is 5, giving the full ISIN US0378331005. Complete a securities identifier before you print or store it, or check a…
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ISMN check digit
The twelve digits 979023067118 get the check digit 7, so the full music number is 9790230671187. Complete the ISMN of a score, a set of parts or a digital…
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