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 559th bojernico 806 96 449ms 6 Apr 2023 562nd edsrzf 🇳🇿 806 114 7ms 22 Aug 2025 563rd emgordon154 806 234 1,451ms 18 Apr 2025 563rd error256 806 234 1,485ms 8 Feb 2026 565th emgordon154 805 125 6ms 20 days ago 566th h3ra993huskp 🇯🇵 805 133 496ms 30 Nov 2025 567th scpchicken 🇵🇼 804 58 3ms 22 Feb 2023 567th blaztoma 🇱🇹 804 58 3ms 16 days ago 569th mtirado1 804 108 2ms 6 May 2023 570th typeswitch-dev 🇵🇹 804 121 8ms 14 Aug 2023 571st kg583 🇺🇸 804 155 34ms 4 days ago 572nd Babafaba 803 94 475ms 28 Nov 2025 572nd snoozingnewt 🇨🇦 803 94 497ms 20 Feb 2026 574th btjones0 803 110 9ms 25 Jan 2022 574th adamnielson42 🇺🇸 803 110 10ms 25 Apr 2023 574th sultan 803 110 10ms 24 Feb 2024 574th fgrosshans 🇫🇷 803 110 10ms 16 Jul 2024 574th InigoK 🇺🇸 803 110 9ms 22 Sep 2025 574th albanian-laundromat 803 110 10ms 7 Nov 2025 574th vhoulbreque 🇫🇷 803 110 10ms 25 Nov 2025 581st madex 🇩🇪 803 115 2ms 10 Apr 2022 581st FragmentedCurve 803 115 2ms 22 Nov 2023 581st mathisfun271 803 115 2ms 5 Feb 2024 584th Shanethegamer 🇺🇸 803 168 25ms 28 Apr 2022 585th Shanethegamer 🇺🇸 800 89 133ms 8 Jan 2025 585th emplv 🇱🇻 800 89 135ms 28 Mar 2025 585th ovs-code 🇩🇪 800 89 139ms 17 Apr 2025 588th akshatj27 🇦🇶 799 68 35ms 10 Jan 2022 588th SirBogman 🇺🇸 799 68 42ms 19 May 2022 588th Shanethegamer 🇺🇸 799 68 35ms 27 May 2022 588th Haksell 🇦🇶 799 68 37ms 23 Feb 2023 588th anter69 🇭🇺 799 68 38ms 20 Nov 2023 593rd GolfingSuccess 🇬🇷 799 156 34ms 39 hours ago 594th Yewzir 🇧🇪 799 185 1,707ms 21 May 2024 595th igmcdowell 798 89 11ms 24 Feb 2022 595th inventshah 798 89 11ms 21 Jun 2022 595th olleicua 🇺🇸 798 89 10ms 3 Feb 2024 595th kpal81xd 798 89 10ms 15 Sep 2024 599th adyache 🇺🇸 798 92 9ms 2 Aug 2023 600th stefangimmillaro 798 152 152ms 28 Oct 2023 601st Shanethegamer 🇺🇸 797 115 374ms 21 Apr 2022 602nd neihousaigaai 796 111 10ms 11 Jan 2022 602nd knutae 🇳🇴 796 111 9ms 18 Jan 2022 602nd rschwa6308 🇺🇸 796 111 10ms 22 Mar 2023 602nd zbreit 🇺🇸 796 111 9ms 22 Mar 2023 602nd plcc0 796 111 10ms 3 Mar 2025 602nd emgordon154 796 111 10ms 25 Mar 2025 602nd BREMAUCY 🇫🇷 796 111 10ms 15 Apr 2025 602nd now4est 🇯🇵 796 111 10ms 25 Sep 2025 610th MeWhenI 🇻🇦 796 116 2ms 5 Jul 2024 611th SirBogman 🇺🇸 795 39 41ms 4 Oct 2022 612th prplz 🇦🇺 795 70 305ms 19 Jan 2022 612th SirBogman 🇺🇸 795 70 295ms 19 May 2022 614th error256 794 74 742ms 13 Feb 2026 615th ovs-code 🇩🇪 793 153 226ms 21 Jun 2023 616th Salutations45 792 66 2ms 2 Jan 2025 617th KrausRaus 🇺🇸 792 106 4ms 11 Nov 2023 618th GrayJoKing 🇦🇺 791 59 3ms 14 Jan 2022 618th Shanethegamer 🇺🇸 791 59 3ms 20 Jun 2022 620th Shanethegamer 🇺🇸 791 90 2,763ms 28 Oct 2024 620th DialFrost 🇸🇬 791 90 131ms 3 Nov 2024 622nd sean-niemann 🇺🇸 791 127 40ms 1 Dec 2023 623rd tomh1012 790 98 437ms 31 Jan 2022 623rd pkim 790 98 450ms 6 Apr 2023 623rd danielxbauer 790 98 459ms 6 Apr 2023 623rd meinsiedler 790 98 412ms 6 Apr 2023 623rd postie77 790 98 461ms 8 May 2023 628th weliveinhell 🇭🇹 789 90 11ms 11 Jan 2024 629th m-tkach 🇺🇦 789 117 1ms 11 Jan 2022 629th prestosilver 🇺🇸 789 117 2ms 16 Dec 2025 631st 4hg 🇺🇸 788 69 35ms 30 Nov 2022 631st Andriamanitra 🇫🇮 788 69 39ms 17 Apr 2023 633rd guilhem-roy 🇫🇷 788 112 9ms 5 Jun 2022 633rd ahmetdemirag 🇨🇾 788 112 10ms 30 Jun 2024 633rd CommandLeo 🇮🇹 788 112 10ms 3 Nov 2025 633rd denkyuu1 788 112 10ms 23 Feb 2026 637th lynn 788 154 163ms 11 Mar 2022 637th The3gs 788 154 157ms 18 Aug 2023 639th dokutan 787 130 8ms 21 Jun 2024 640th edsrzf 🇳🇿 787 133 1,256ms 26 Apr 2025 First Prev 561–640 of 1,620 Next Last