| 2-step | 1991 | ⊕ United States | |||
| ABC | 1991 | ↓ ↑ ⊕ Specialised Languages | ⊕ Sound-Performance | ⊕ United Kingdom | |
| ACIS | 1991 | ||||
| AIMMS | 1991 | ||||
| AKL | 1991 | ⊕ Japan | Andorra Kernel Language | ||
| AL | 1991 | ↓ ↑ ⊕ Specialised Languages | ⊕ United States | TSL knowledge representation language | |
| ALJABR | 1991 | ⊕ United States | MACSYMA for the Mac | ||
| ALMS | 1991 | parallel langauge | |||
| ANALITIK-91 | 1991 | ⊕ United States | |||
| Andorra-I | 1991 | ↓ ↑ ⊕ Specialised Languages | ⊕ United Kingdom | Bristol U Andorra | |
| ASCEND | 1991 | ||||
| Bob | 1991 | Tiny object-oriented language | |||
| C flat | 1991 | ↓ ↑ ⊕ Specialised Languages | ⊕ United States | obscurantist C | |
| C+@ | 1991 | ↓ ↑ ⊕ Multi-purpose | ⊕ United States | Simplified C | |
| C++Linda | 1991 | ⊕ Germany | |||
| Calico | 1991 | ⊕ United States | |||
| cantata | 1991 | ⊕ United States | |||
| CECIL | 1991 | ↓ ↑ ⊕ Multi-purpose | ⊕ Prototyping | ⊕ United States | Prototyped OOL |
| Closette | 1991 | ⊕ United States | |||
| ConC | 1991 | ||||
| coq | 1991 | ↓ ↑ ⊕ String and List Processing | ⊕ France | ||
| CPL | 1991 | ↓ ↑ ⊕ Specialised Languages | ⊕ United Kingdom | Categorical Programming Lanugage | |
| CUP | 1991 | ⊕ Japan | |||
| DataVis | 1991 | ⊕ United States | |||
| DDL | 1991 | ↓ ↑ ⊕ Business Data Processing | ⊕ United States | Data Definition Language | |
| Dee | 1991 | ⊕ Canada | |||
| DEL | 1991 | ↓ ↑ ⊕ Multi-purpose | ⊕ Brazil | Data Entry Language | |
| Delirium | 1991 | ⊕ United States | |||
| DESMO | 1991 | ⊕ Germany | |||
| DICE | 1991 | ↓ ↑ ⊕ Specialised Languages | ⊕ United States | OO CAE system | |
| DICON | 1991 | ⊕ United States | |||
| DOHJI | 1991 | ⊕ Japan | |||
| DTL | 1991 | ⊕ Netherlands | |||
| Duration Calculus | 1991 | ⊕ United Kingdom | |||
| dVoice | 1991 | ↓ ↑ ⊕ Business Data Processing | ⊕ Labelled Matrix | ⊕ United States | Voice-capable dBase |
| DYNO | 1991 | ⊕ United States | |||
| EDX/EDL | 1991 | ||||
| Eiffel 3 | 1991 | ⊕ France | |||
| Eiffel/S | 1991 | ↓ ↑ ⊕ Multi-purpose | ⊕ Germany | SIG Eiffel | |
| ELSIE | 1991 | ⊕ United Kingdom | |||
| EPL | 1991 | ↓ ↑ ⊕ Numerical Scientific | ⊕ Algebraic | ⊕ United States | Equational language for parallel scientific applications |
| EPOCH | 1991 | ⊕ Japan | |||
| ERAE | 1991 | ||||
| Erasmus | 1991 | ||||
| ESL | 1991 | ↓ ↑ ⊕ Specialised Languages | ⊕ Robotics | ⊕ United States | |
| expect | 1991 | ↓ ↑ ⊕ Specialised Languages | ⊕ United States | ||
| Express | 1991 | ↓ ↑ ⊕ Business Data Processing | ⊕ United States | NIST Data definition language | |
| Fibonacci | 1991 | ⊕ International | |||
| FLEX | 1991 | ↓ ↑ ⊕ Multi-purpose | ⊕ United States | Dynamic real-time language | |
| FORKADS | 1991 | ⊕ United States | |||
| FORMAN | 1991 | ⊕ United States | |||
| Formula | 1991 | ⊕ United States | |||
| Fortran D | 1991 | ↓ ↑ ⊕ Numerical Scientific | ⊕ United States | Parallel extension to FORTAN | |
| Fortran-Linda | 1991 | ⊕ Ireland | |||
| FX-91 | 1991 | ⊕ United States | |||
| GAML | 1991 | Parallel Lazy ML | |||
| GCLA | 1991 | ⊕ Sweden | |||
| Glue-Nail | 1991 | ⊕ United States | |||
| Gofer | 1991 | ⊕ United Kingdom | |||
| GRAP | 1991 | ↓ ↑ ⊕ Experimental and other | ⊕ United States | ||
| Grapes | 1991 | ||||
| Haskell# | 1991 | ↓ ↑ ⊕ Experimental and other | ⊕ United States | Parallel dialect of Haskell | |
| Hence | 1991 | Visual languages | |||
| hepawk | 1991 | ⊕ Germany | |||
| HPCode-Plus | 1991 | ⊕ United States | |||
| HSL | 1991 | ⊕ United States | |||
| HyTime | 1991 | ⊕ United States | |||
| iGlue | 1991 | ⊕ United States | |||
| IRDATA | 1991 | ⊕ Germany | |||
| Iris | 1991 | ⊕ United States | |||
| Isabelle-91 | 1991 | ⊕ United States | |||
| ISL | 1991 | ⊕ United States | Interface Specification Language | ||
| ITL | 1991 | ⊕ Italy | |||
| Jade | 1991 | ⊕ United States | Device independant parallel programming language | ||
| jBasic | 1991 | ⊕ United States | |||
| JOSIE | 1991 | ↓ ↑ ⊕ Specialised Languages | ⊕ Frame languages | ⊕ United States | |
| Kaleidoscope'91 | 1991 | ⊕ United States | |||
| Kid | 1991 | ⊕ United States | |||
| King Kong | 1991 | ⊕ Frame languages | ⊕ United States | ||
| KMODEL | 1991 | ⊕ Germany | |||
| KRIS | 1991 | ⊕ United States | |||
| LCL | 1991 | ||||
| LIANA | 1991 | ⊕ United States | Interpretive c-like language | ||
| Lingo | 1991 | ↓ ↑ ⊕ Specialised Languages | ⊕ Animation | ⊕ United States | Macromedia animation scripting language |
| LinxBasic | 1991 | ↓ ↑ ⊕ Specialised Languages | ⊕ Street basics | ⊕ Canada | Generator language |
| log | 1991 | ⊕ United States | |||
| LOLA | 1991 | ⊕ Germany | |||
| LPMud | 1991 | ⊕ Sweden | |||
| Lucid representations | 1991 | ⊕ United States | |||
| Lucinda | 1991 | ⊕ United Kingdom | |||
| MACL | 1991 | ⊕ United States | Macintosh Allegro CL | ||
| MacOberon | 1991 | ⊕ Switzerland | |||
| Maggiolo-Schettini 3 | 1991 | ||||
| MAL | 1991 | Modal action logic | |||
| Maril | 1991 | ||||
| mawk | 1991 | ||||
| MCL | 1991 | ⊕ United States | Macintosh Common LISP | ||
| Megalog | 1991 | ⊕ United Kingdom | |||
| Meroon | 1991 | ⊕ France | |||
| MIDAS | 1991 | ⊕ United States | Bell Labs Simulator | ||
| Miracula | 1991 | ⊕ United Kingdom | |||
| M-LISP | 1991 | ↓ ↑ ⊕ String and List Processing | ⊕ Lazy Evaluation LISPs | ⊕ United States | |
| Mma | 1991 | ↓ ↑ ⊕ Specialised Languages | ⊕ Algebraic | ⊕ United States | Mathematical system |
| Modula SC | 1991 | ↓ ↑ ⊕ Multi-purpose | ⊕ Switzerland | Modula 2 with Scientific Ccomputing extensions | |
| Morpheus | 1991 | ||||
| NESL | 1991 | ⊕ United States | |||
| Neuro-Prolog | 1991 | ↓ ↑ ⊕ String and List Processing | ⊕ Horn clause | ⊕ Japan | |
| Neuro-Prolog II | 1991 | ↓ ↑ ⊕ String and List Processing | ⊕ Horn clause | ⊕ Japan | |
| nML | 1991 | ↓ ↑ ⊕ Specialised Languages | ⊕ Grammar and Syntax-oriented | ⊕ United States | Grammar specification language |
| NSL | 1991 | ||||
| NSL | 1991 | ⊕ United States | |||
| NUA-Prolog | 1991 | ↓ ↑ ⊕ String and List Processing | ⊕ Horn clause | ⊕ United Kingdom | Extension to the WAM for Parallel Andorra |
| NUE-Prolog | 1991 | ↓ ↑ ⊕ String and List Processing | ⊕ Horn clause | ⊕ Australia | |
| Oberon-2 | 1991 | ⊕ Switzerland | |||
| Object-Oriented Turing | 1991 | ⊕ Canada | |||
| Object-Z | 1991 | ⊕ Australia | |||
| Omega | 1991 | ↓ ↑ ⊕ Specialised Languages | ⊕ Prototyping | ⊕ Austria | Protype based OOL |
| OOT | 1991 | ⊕ Canada | |||
| O'Small | 1991 | ⊕ United States | |||
| Paragon | 1991 | ||||
| Parallaxis 2 | 1991 | ⊕ Germany | |||
| ParaMacs | 1991 | ⊕ United States | |||
| PARIS | 1991 | ↓ ↑ ⊕ Multi-purpose | ⊕ Pascals | ⊕ Russian Federation | Siberian parallel Pascal |
| Parsec | 1991 | ↓ ↑ ⊕ Specialised Languages | ⊕ United States | C-based parallel simulation language | |
| PARULEL | 1991 | ||||
| Pascal-Linda | 1991 | ↓ ↑ ⊕ Multi-purpose | ⊕ Pascals | ⊕ United Kingdom | |
| Pascal-XSC | 1991 | ↓ ↑ ⊕ Multi-purpose | ⊕ Pascals | ⊕ Germany | |
| pC++ | 1991 | ||||
| Persimmon | 1991 | ⊕ Australia | |||
| PFC | 1991 | ⊕ United States | |||
| Pi Calculus | 1991 | ⊕ United Kingdom | |||
| PICL | 1991 | ⊕ Italy | |||
| PICL | 1991 | ⊕ United States | |||
| PICT | 1991 | ⊕ United Kingdom | |||
| PiCTeX | 1991 | ↓ ↑ ⊕ Specialised Languages | ⊕ 2d shape | ⊕ United States | Picture extensions to TeX |
| Poco | 1991 | ⊕ United States | |||
| PREDULA | 1991 | ↓ ↑ ⊕ Experimental and other | ⊕ Pascals | ⊕ Sweden | Data-parallel Pascal |
| PROCOL | 1991 | ||||
| PROGRES | 1991 | ⊕ Germany | |||
| PROOF/L | 1991 | ||||
| PROSIT | 1991 | ⊕ United States | Programming in SItuation Theory | ||
| pSather | 1991 | ↓ ↑ ⊕ Experimental and other | ⊕ United States | parallel Sather | |
| PSDL | 1991 | ||||
| Python | 1991 | ⊕ Netherlands | String based scripting language | ||
| QUINE | 1991 | ⊕ United States | |||
| Quintec Prolog | 1991 | ↓ ↑ ⊕ String and List Processing | ⊕ Horn clause | ⊕ United Kingdom | |
| Quintec-Objects | 1991 | ⊕ United Kingdom | |||
| Quixote | 1991 | ⊕ Japan | |||
| RC | 1991 | ↓ ↑ ⊕ Experimental and other | ⊕ France | Reactive C | |
| RDL | 1991 | ⊕ United States | |||
| Real-Time Concurrent C | 1991 | ↓ ↑ ⊕ Experimental and other | ⊕ CPL, BCPL and B | ⊕ United States | Real-time extensions to Concurrent C |
| REDUCE/OR | 1991 | ⊕ United States | parallel language | ||
| R-Prolog | 1991 | ↓ ↑ ⊕ String and List Processing | ⊕ Horn clause | ||
| RSML | 1991 | ⊕ Decision tables | ⊕ United States | Hardware requirements DT language | |
| Sampletalk | 1991 | ⊕ Russian Federation | |||
| Sather | 1991 | ⊕ United States | |||
| Sather 0 | 1991 | ⊕ United States | ISCI version of programming by contract | ||
| Self-91 | 1991 | ↓ ↑ ⊕ Multi-purpose | ⊕ United States | Instance-based OO Language | |
| SetLog | 1991 | ⊕ United States | |||
| Sim++ | 1991 | ||||
| Siri | 1991 | ⊕ United States | |||
| SNOOPS | 1991 | ⊕ United States | |||
| Sqil | 1991 | ↓ ↑ ⊕ Specialised Languages | ⊕ France | Intermediate language for functional programming languages | |
| SQLMP | 1991 | ⊕ United States | Linear programmign extensions to SQL | ||
| STAR | 1991 | ⊕ Russian Federation | |||
| Starlog | 1991 | ↓ ↑ ⊕ Specialised Languages | ⊕ Interval time | ⊕ Canada | Stratified Temporal Prolog |
| STARSET | 1991 | ↓ ↑ ⊕ Business Data Processing | ⊕ Russian Federation | Distributed databases programming language | |
| STARSIM | 1991 | ↓ ↑ ⊕ String and List Processing | ⊕ United States | Simulator for *Lisp | |
| Synon/1 | 1991 | ||||
| SYNON/2 | 1991 | ||||
| Terse | 1991 | ||||
| TIM | 1991 | ⊕ France | |||
| TL0 | 1991 | ⊕ United States | |||
| Tortoise | 1991 | ||||
| TPDL* | 1991 | ||||
| Trafola-H | 1991 | ||||
| UBASIC | 1991 | ↓ ↑ ⊕ Numerical Scientific | ⊕ Japan | Symbolic maths BASIC | |
| UDL/I | 1991 | ⊕ Japan | |||
| UltraCPL | 1991 | ↓ ↑ ⊕ Specialised Languages | ⊕ Numerical Control | ⊕ United States | CAM systems language |
| USL | 1991 | ⊕ United States | |||
| VCODE | 1991 | ⊕ United States | Intermediate language used in the compilation of NESL | ||
| VCODE | 1991 | ⊕ United States | Intermediate language used in the compilation of C+@ | ||
| Venus | 1991 | ||||
| VPL | 1991 | ||||
| WCL | 1991 | ↓ ↑ ⊕ String and List Processing | ⊕ Lazy Evaluation LISPs | ⊕ United States | CLX optimised for multiple programs |
| WinNodal | 1991 | ||||
| WinSTRUDL | 1991 | ↓ ↑ ⊕ Specialised Languages | ⊕ United States | STRUDL for Windows | |
| Xfun | 1991 | ⊕ France | |||
| x-kernel | 1991 | ||||
| Zipcode | 1991 | Parallel language at Lawrence Livermore | |||
| Zuse | 1991 | ↓ ↑ ⊕ Multi-purpose | ⊕ Pascals | ⊕ Sweden |