The Gray Code Decoder and Gray Code Encoder holes will go live in approximately 4 days. Why not try and solve them ahead of time?
ISBN in all languages in bytes. Achievements Cheevos Holes Languages Medals Miscellaneous All Holes 12 Days of Christmas 24 Game 99 Bottles of Beer Abundant Numbers Abundant Numbers (Long) Arabic to Roman Arithmetic Numbers Arrows Ascending Primes ASCII Table Billiards brainfuck Calendar Card Number Validation Catalan Numbers Catalan’s Constant Christmas Trees Collatz Continued Fractions CSS Colors Cubes Day of Week DFA Simulator Diamonds Divisors Emirp Numbers Emirp Numbers (Long) Emojify Evil Numbers Evil Numbers (Long) Factorial Factorisation Farey Sequence Fibonacci Fizz Buzz Foo Fizz Buzz Bar Forsyth–Edwards Notation Fractions Game of Life Gijswijt’s Sequence Happy Numbers Happy Numbers (Long) Hexdump Hilbert Curve Intersection Inventory Sequence ISBN Jacobi Symbol Kaprekar Numbers Kolakoski Constant Kolakoski Sequence Leap Years Levenshtein Distance Leyland Numbers ln 2 Look and Say Lucky Numbers Lucky Tickets Mahjong Mandelbrot Maze Medal Tally Minesweeper Morse Decoder Morse Encoder Multitap Input Musical Chords N Queens Niven Numbers Niven Numbers (Long) Number Spiral Odious Numbers Odious Numbers (Long) Ordinal Numbers PalindromemordnilaP Pangram Grep Partition Numbers Pascal’s Triangle Pernicious Numbers Pernicious Numbers (Long) Poker Polyominoes Prime Numbers Prime Numbers (Long) Proximity Grid QR Decoder Quine Recamán Repeating Decimals Reverse Polish Notation Reversi Rijndael S-box Rock-paper-scissors-Spock-lizard Roman to Arabic ROT13 Rule 110 Scrambled Sort Set Seven Segment SI Units Sierpiński Triangle Smith Numbers Spelling Numbers Star Wars GPT Star Wars Opening Crawl Sudoku Sudoku (Fill-in) Ten-pin Bowling Tic-tac-toe Time Distance Tongue-twisters Topological Sort Tower of Hanoi Transpose Sentence Trinomial Triangle United States Vampire Numbers Van Eck Sequence Zeckendorf Representation Zodiac Signs γ λ π τ φ √2 𝑒 Alphabetic Numbers Apéry’s Constant Binary Lambda Calculus Connect Four Crossword CSS Colors (Inverse) CSS Grid Ellipse Perimeters Flags Floyd-Steinberg Dithering Gray Code Decoder Gray Code Encoder Hexagonal Spiral Highly Composite Numbers NFA Simulator Numbrix Odd Polyomino Tiling p-adic Expansion Polygon Triangulations QR Encoder Quadratic Formula Rectangle Fill Semiprime Numbers Smooth Numbers Snake Sphenic Numbers Taxicab Numbers Turtle Tutorial All Languages ><> ALGOL 68 ArkScript Assembly AWK Bash BASIC Berry brainfuck C C# C++ Civet Clojure COBOL Coconut Common Lisp Crystal D Dart Elixir Erlang F# Factor Forth Fortran Gleam Go GolfScript Groovy Haskell Hexagony J Janet Java JavaScript jq Julia K Kotlin Lua Nim OCaml Pascal Perl PHP PowerShell Prolog Python R Raku Rockstar Ruby Rust Scheme sed SQL Swift Tcl TeX V VimL Wren Zig 05AB1E APL Arturo Befunge BQN CJam CoffeeScript Egel Fennel Harbour Hare Haxe Hush Hy iogii Knight Lily Luau Odin Picat Qore Racket Rebol Rexx Scala Squirrel Stax Uiua Umka Vala Vyxal Bytes Chars Scoring Bytes Chars Language All ><> ALGOL 68 ArkScript Assembly AWK Bash BASIC Berry brainfuck C C# C++ Civet Clojure COBOL Coconut Common Lisp Crystal D Dart Elixir Erlang F# Factor Forth Fortran Gleam Go GolfScript Groovy Haskell Hexagony J Janet Java JavaScript jq Julia K Kotlin Lua Nim OCaml Pascal Perl PHP PowerShell Prolog Python R Raku Rockstar Ruby Rust Scheme sed SQL Swift Tcl TeX V VimL Wren Zig Experimental Language 05AB1E APL Arturo Befunge BQN CJam CoffeeScript Egel Fennel Harbour Hare Haxe Hush Hy iogii Knight Lily Luau Odin Picat Qore Racket Rebol Rexx Scala Squirrel Stax Uiua Umka Vala Vyxal Hole All 12 Days of Christmas 24 Game 99 Bottles of Beer Abundant Numbers Abundant Numbers (Long) Arabic to Roman Arithmetic Numbers Arrows Ascending Primes ASCII Table Billiards brainfuck Calendar Card Number Validation Catalan Numbers Catalan’s Constant Christmas Trees Collatz Continued Fractions CSS Colors Cubes Day of Week DFA Simulator Diamonds Divisors Emirp Numbers Emirp Numbers (Long) Emojify Evil Numbers Evil Numbers (Long) Factorial Factorisation Farey Sequence Fibonacci Fizz Buzz Foo Fizz Buzz Bar Forsyth–Edwards Notation Fractions Game of Life Gijswijt’s Sequence Happy Numbers Happy Numbers (Long) Hexdump Hilbert Curve Intersection Inventory Sequence ISBN Jacobi Symbol Kaprekar Numbers Kolakoski Constant Kolakoski Sequence Leap Years Levenshtein Distance Leyland Numbers ln 2 Look and Say Lucky Numbers Lucky Tickets Mahjong Mandelbrot Maze Medal Tally Minesweeper Morse Decoder Morse Encoder Multitap Input Musical Chords N Queens Niven Numbers Niven Numbers (Long) Number Spiral Odious Numbers Odious Numbers (Long) Ordinal Numbers PalindromemordnilaP Pangram Grep Partition Numbers Pascal’s Triangle Pernicious Numbers Pernicious Numbers (Long) Poker Polyominoes Prime Numbers Prime Numbers (Long) Proximity Grid QR Decoder Quine Recamán Repeating Decimals Reverse Polish Notation Reversi Rijndael S-box Rock-paper-scissors-Spock-lizard Roman to Arabic ROT13 Rule 110 Scrambled Sort Set Seven Segment SI Units Sierpiński Triangle Smith Numbers Spelling Numbers Star Wars GPT Star Wars Opening Crawl Sudoku Sudoku (Fill-in) Ten-pin Bowling Tic-tac-toe Time Distance Tongue-twisters Topological Sort Tower of Hanoi Transpose Sentence Trinomial Triangle United States Vampire Numbers Van Eck Sequence Zeckendorf Representation Zodiac Signs γ λ π τ φ √2 𝑒 Experimental Hole Alphabetic Numbers Apéry’s Constant Binary Lambda Calculus Connect Four Crossword CSS Colors (Inverse) CSS Grid Ellipse Perimeters Flags Floyd-Steinberg Dithering Gray Code Decoder Gray Code Encoder Hexagonal Spiral Highly Composite Numbers NFA Simulator Numbrix Odd Polyomino Tiling p-adic Expansion Polygon Triangulations QR Encoder Quadratic Formula Rectangle Fill Semiprime Numbers Smooth Numbers Snake Sphenic Numbers Taxicab Numbers Turtle Tutorial # Golfer Points Bytes Time Submitted 481st Mandrzejy 🇵🇱 829 134 79ms 13 Sep 2024 482nd rucin93 🇵🇱 828 86 138ms 13 days ago 483rd Shanethegamer 🇺🇸 828 107 152ms 24 May 2025 484th GrayJoKing 🇦🇺 828 130 2ms 12 Sep 2022 485th CLOStrophobic 🇮🇹 827 123 8ms 21 Jan 2025 485th kg583 🇺🇸 827 123 8ms 20 Feb 2026 487th quimey 825 107 10ms 7 Mar 2023 487th fourth-bit 825 107 10ms 10 Jul 2024 487th fuzzylojik-golf 🇺🇸 825 107 10ms 19 May 2025 487th solisolu 825 107 10ms 25 Nov 2025 491st Shanethegamer 🇺🇸 825 112 1ms 20 Apr 2022 492nd Steffan153 🇫🇮 825 151 33ms 4 days ago 493rd GrayJoKing 🇦🇺 824 99 4ms 20 Sep 2023 494th m-tkach 🇺🇦 824 130 535ms 25 Sep 2025 495th error256 823 66 37ms 8 May 2025 496th annaproxy 823 94 438ms 19 Mar 2022 497th MeWhenI 🇻🇦 823 102 5ms 26 Nov 2023 498th primo-ppcg 🇹🇭 823 164 25ms 25 Jun 2022 499th Frowny 822 53 32ms 11 Jan 2022 500th Irratix 🇳🇱 822 135 452ms 14 May 2022 501st DialFrost 🇸🇬 822 286 140ms 22 Apr 2025 501st frankgraziano 822 286 651ms 31 Jan 2026 503rd inventshah 821 92 474ms 21 Jan 2024 503rd GolfingSuccess 🇬🇷 821 92 402ms 2 Mar 2024 505th Shanethegamer 🇺🇸 821 124 6ms 27 Aug 2024 506th Steffan153 🇫🇮 819 57 3ms 6 Jan 2023 506th Natanaelel 🇸🇪 819 57 4ms 13 May 2023 508th stefangimmillaro 818 87 2,700ms 24 Nov 2024 508th emgordon154 818 87 2,768ms 6 Mar 2025 510th prplz 🇦🇺 818 108 10ms 11 Jan 2022 510th galloj 🇨🇿 818 108 10ms 21 Sep 2022 510th TaserTheFox 🇺🇸 818 108 9ms 3 Apr 2023 510th jatloe 818 108 10ms 26 Aug 2024 510th cros107 🇦🇺 818 108 10ms 10 Aug 2025 515th btnlq 818 125 15ms 12 Jan 2022 516th Yewzir 🇧🇪 817 113 1ms 29 Nov 2023 516th drabart 🇵🇱 817 113 2ms 18 Dec 2023 518th sean-niemann 🇺🇸 817 163 298ms 30 Aug 2023 518th Yewzir 🇧🇪 817 163 288ms 7 Feb 2024 518th CaedenHarper 🇨🇦 817 163 288ms 2 Nov 2025 521st emgordon154 817 181 1,625ms 22 Dec 2025 522nd lynn 816 38 41ms 22 Jul 2022 522nd MeWhenI 🇻🇦 816 38 44ms 25 Aug 2022 522nd 5cw 🇺🇸 816 38 2ms 27 May 2024 522nd emgordon154 816 38 3ms 18 days ago 526th DialFrost 🇸🇬 816 72 755ms 4 Sep 2025 527th itsh01 816 87 11ms 13 Mar 2022 527th AlephSquirrel 816 87 11ms 15 Feb 2023 527th danielphilpottwork 816 87 11ms 20 Dec 2023 530th DialFrost 🇸🇬 816 118 461ms 27 Nov 2024 531st Shanethegamer 🇺🇸 816 136 56ms 20 Apr 2022 532nd janbehrens 🇩🇪 815 103 4ms 2 Jul 2023 533rd plcc0 814 125 6ms 23 Mar 2025 534th scpchicken 🇵🇼 813 55 135ms 13 Mar 2022 535th Shanethegamer 🇺🇸 812 93 458ms 16 Jan 2024 535th Yewzir 🇧🇪 812 93 513ms 22 Jun 2024 537th jotslo 🇬🇧 812 107 2ms 17 Jul 2022 538th janlelis 811 67 36ms 11 Jan 2022 538th stefangimmillaro 811 67 40ms 26 Dec 2024 540th chunes3 🇺🇸 811 100 70ms 15 Sep 2023 540th Natanaelel 🇸🇪 811 100 70ms 8 Dec 2023 542nd GrayJoKing 🇦🇺 811 113 401ms 24 Jul 2025 543rd error256 811 132 385ms 21 Nov 2025 544th kg583 🇺🇸 811 154 38ms 17 Nov 2025 545th ZakkkkAttackkkk 🇵🇭 810 109 10ms 23 Feb 2022 545th cefqrn 810 109 10ms 24 Dec 2022 545th AlexanderFair 810 109 10ms 11 Jul 2023 545th PixelSoftwareStudios 🇺🇸 810 109 10ms 6 Jul 2024 545th andrewjc2000 810 109 9ms 9 Mar 2025 545th tomh1012 810 109 10ms 22 days ago 551st Mandrzejy 🇵🇱 810 114 1ms 13 Sep 2024 551st AZTECCO 810 114 1ms 16 Sep 2025 553rd m-tkach 🇺🇦 810 137 56ms 15 Jan 2022 553rd sean-niemann 🇺🇸 810 137 58ms 3 Feb 2024 555th GrayJoKing 🇦🇺 810 152 29ms 18 Jul 2023 555th m-tkach 🇺🇦 810 152 29ms 10 Feb 2026 557th albanian-laundromat 809 133 3ms 22 Sep 2025 558th MeWhenI 🇻🇦 807 101 4ms 23 May 2023 559th ScottHamper 806 96 437ms 26 Feb 2022 559th stefangimmillaro 806 96 419ms 5 Jan 2023 First Prev 481–560 of 1,620 Next Last