| IBM Advanced BASIC | 1981 | — | — | 1 |
| IBM BASIC | 1981 | — | — | — |
| IBM Cross System Product | — | — | — | — |
| IBM Informix-4GL | 1986 | — | — | — |
| IBM PL/S | 1960 | — | — | — |
| IBM RPG II | 1965 | — | — | — |
| IBM RPG III | 1978 | — | — | — |
| IBM System/36 BASIC | — | — | — | — |
| Icon | 1977 | procedural programming, structured programming, expression-oriented programming, multi-paradigm programming | dynamic typing | 3 |
| Idris | 2007 | total functional programming, functional programming, purely functional programming | static typing, dependent typing, linear typing, uniqueness typing | — |
| Illumination Software Creator | — | — | — | — |
| ILNumerics.Net | — | object-oriented programming | — | — |
| Impromptu | 2005 | functional programming | dynamic typing | 1 |
| Incr Tcl | 1993 | event-driven programming, functional programming, imperative programming, object-oriented programming | dynamic typing | — |
| Inform | 1993 | procedural programming, declarative programming, object-oriented programming | inference typing | 1 |
| Information Processing Language | 1956 | procedural programming | — | 1 |
| Ink | — | — | — | — |
| Integer BASIC | 1977 | — | — | — |
| Intel Parallel Building Blocks | 2010 | imperative programming | manifest typing, weak typing | — |
| Interactive Data Language | 1977 | array programming | dynamic typing | 1 |
| INTERCAL | 1972 | esoteric programming | — | — |
| Interpress | — | — | — | 1 |
| InterSystems Caché | — | — | — | — |
| Io | 2002 | prototype-based programming, object-oriented programming | dynamic typing, strong typing | 3 |
| Ioke | 2008 | prototype-based programming | — | — |
| Iota and Jot | — | esoteric programming | — | — |
| ISLISP | 1997 | reflective programming, procedural programming, functional programming, metaprogramming, object-oriented programming | — | — |
| ISWIM | 1966 | functional programming, imperative programming | — | 1 |
| Itk | 1993 | multi-paradigm programming | dynamic typing | — |
| Ixi lang | — | — | — | — |