| Itk | 1993 | multi-paradigm programming | dynamic typing | — |
| Ixi lang | — | — | — | — |
| J | 1990 | functional programming, function-level programming, tacit programming, multi-paradigm programming, array programming, object-oriented programming | dynamic typing | 2 |
| J# | 2002 | structured programming, imperative programming, object-oriented programming | — | 1 |
| Jai | — | procedural programming | static typing, strong typing | — |
| Jakarta Expression Language | — | — | — | — |
| Jakt | 2022 | — | — | — |
| JaM | 1978 | — | — | — |
| Janus | 1982 | procedural programming, reversible computing, imperative programming | — | — |
| Janus | 1990 | concurrent constraint logic programming | — | — |
| Jasmin | — | object-oriented programming | — | — |
| JASS | 2001 | — | — | — |
| Java | 1995 | generic programming, reflective programming, functional programming, structured programming, imperative programming, class-based programming, concurrent object-oriented programming, component-based software engineering, object-oriented programming | manifest typing, static typing, nominative typing, safe typing, strong typing | 43 |
| Java Agent Development Framework | — | — | — | — |
| JavaFX Script | 2008 | scripting language, declarative programming | static typing | — |
| JavaScript | 1995 | generic programming, event-driven programming, prototype-based programming, functional programming, imperative programming, aspect-oriented programming | dynamic typing, prototype-based programming, duck typing | 25 |
| JavaScript for Automation | — | — | — | — |
| Jess | 1995 | logic programming, declarative programming | — | — |
| Jim Tcl | — | — | — | — |
| Jmax | — | — | — | — |
| JModelica.org | — | declarative programming | — | — |
| JoCaml | — | — | — | — |
| Joe-E | 2004 | Object-capability model | — | — |
| Join Java | 2000 | reflective programming, concurrent computing, procedural programming | — | — |
| Jolie | — | — | — | — |
| JOSS | 1963 | — | — | 3 |
| Joule | 1996 | dataflow programming, imperative programming, object-oriented programming | — | 1 |
| JOVIAL | 1960 | procedural programming, structured programming, imperative programming | static typing, safe typing, structural typing, strong typing | 1 |
| Joy | 2001 | purely functional programming, concatenative programming, stack-oriented programming | dynamic typing, strong typing | 2 |
| Joyce | 1980 | concurrent computing, procedural programming | — | 1 |
| Jq | 2012 | functional programming, tacit programming | — | — |
| JS++ | 2011 | generic programming, functional programming, structured programming, imperative programming, object-oriented programming | dynamic typing, gradual typing, static typing | — |
| JScript | 1996 | prototype-based programming, object-oriented programming | dynamic typing, duck typing, weak typing | — |
| JScript .NET | — | — | dynamic typing, duck typing, weak typing | — |
| Jsish | — | multi-paradigm programming | dynamic typing, duck typing | — |
| JSX | 2012 | — | — | — |
| Judoscript | 2001 | object-oriented programming | dynamic typing, strong typing | — |
| Julia | 2009 | procedural programming, multiple dispatch, functional programming, parallel computing, imperative programming, multi-paradigm programming, array programming, metaprogramming, object-oriented programming | dynamic typing, nominative typing, parametric polymorphism, strong typing | — |
| Julia | — | — | — | — |
| K | 1993 | functional programming, array programming | dynamic typing, strong typing | 1 |
| Kaitai Struct | — | — | — | — |
| Kalaam | 2020 | — | — | — |
| Kaleidoscope | 1994 | procedural programming, imperative programming, constraint programming, object-oriented programming | — | — |
| Kalimat | — | — | — | — |
| Karel | 1981 | procedural programming | — | 1 |
| Kawa | 1998 | scripting language | — | — |
| Kent Recursive Calculator | 1981 | functional programming | — | 1 |
| Keykit | — | object-oriented programming | — | — |
| Kinetic Rule Language | 2007 | event-driven programming, rule-based programming | dynamic typing, weak typing | — |
| Kiste | 2026 | — | — | — |
| KiXtart | 1991 | — | — | — |
| KL0 | — | — | — | — |
| KM | — | knowledge representation and reasoning, declarative programming | — | 1 |
| Kodu Game Lab | 2009 | visual programming language | — | — |
| Kojo | 2010 | functional programming, object-oriented programming | strong typing | — |
| KornShell | 1983 | — | — | 1 |
| Kotlin | 2011 | generic programming, reflective programming, concurrent computing, functional programming, structured programming, imperative programming, declarative programming, object-oriented programming | static typing, inference typing, strong typing | 2 |
| KRL | 1971 | logic programming, declarative programming | — | — |
| KTurtle | — | — | — | — |
| KUKA Robot Language | — | — | — | — |
| KuMir | — | — | — | — |
| Kyma | 1986 | — | — | — |
| Lasso | 1995 | concurrent computing, procedural programming, structured programming, object-oriented programming | dynamic typing, nominative typing, duck typing | — |
| LC-3 | — | — | — | — |
| Le Lisp | 1981 | — | — | — |
| Lean | 2013 | functional programming | — | 1 |
| Lean 3 file format | — | — | — | — |
| Lean 4 file format | — | — | — | — |
| Leet | — | — | — | — |
| LFE | 2008 | functional programming | dynamic typing, strong typing | — |
| Liberty BASIC | 1992 | event-driven programming | dynamic typing | — |
| LibreOffice Basic | — | — | — | — |
| Light.vn | 2024 | — | — | — |
| Limbo | 1995 | concurrent computing, modular programming | strong typing | 2 |
| Linda | 1985 | — | — | — |
| Linden Scripting Language | — | — | — | — |
| Lingo | 1989 | object-oriented programming | — | — |
| Links | 2006 | — | — | — |
| Linotte | 2005 | object-oriented programming | — | — |
| Lioness | — | — | dynamic typing | — |