| Red | 1978 | Multi-purpose | United States | ||
| RED | 1972 | Strict evaluation FPs | United States | Backus formalism of language | |
| RED1 | 1979 | United States | |||
| REDCODE | 0 | ||||
| RediLisp | 1980 | String and List Processing | Lazy Evaluation LISPs | United States | |
| RedTen | 1985 | Canada | |||
| REDUCE | 1963 | Symbolic | United States | ||
| REDUCE 2 | 1970 | Numerical Scientific | Algebraic | United States | Improved vesion of REDUCE with new format |
| REDUCE 3 | 1983 | United States | |||
| REDUCE/17OO | 1978 | United States | Port of REDUCE | ||
| REDUCE/OR | 1991 | United States | parallel language |