| ALGOL 68 | ⊕ 1968 | ↓ ↑ ⊕ Numerical Scientific | True ALGOL68s | ⊕ International | 3rd generation ALGOL |
| ALGOL 68 Revised | ⊕ 1975 | ↓ ↑ ⊕ Numerical Scientific | True ALGOL68s | ⊕ International | |
| Algol 68 with areas | ⊕ 1972 | ↓ ↑ ⊕ Experimental and other | True ALGOL68s | ⊕ United Kingdom | Addition of areas to Algol 68 |
| ALGOL 68+ | ⊕ 1980 | ↓ ↑ ⊕ Numerical Scientific | True ALGOL68s | ⊕ Netherlands | Superlanguage of ALGOL 68 |
| ALGOL 68C | ⊕ 1975 | ↓ ↑ ⊕ Numerical Scientific | True ALGOL68s | ⊕ United Kingdom | Cambridge Algol 68 |
| ALGOL 68-R | ⊕ 1970 | ↓ ↑ ⊕ Numerical Scientific | True ALGOL68s | ⊕ United Kingdom | |
| ALGOL 68RS | ⊕ 1972 | ↓ ↑ ⊕ Numerical Scientific | True ALGOL68s | ⊕ United Kingdom | Extended RS Algol |
| ALGOL 68-RT | ⊕ 1979 | ↓ ↑ ⊕ Numerical Scientific | True ALGOL68s | ⊕ United Kingdom | Parallel ALGOL 68-R |
| ALGOL 68S | ⊕ 1977 | ↓ ↑ ⊕ Numerical Scientific | True ALGOL68s | ⊕ International | Simplified version of ALGOL 68 |
| Algol H | ⊕ 1975 | ↓ ↑ ⊕ Experimental and other | True ALGOL68s | ⊕ United Kingdom | Proposed extensions to the mode system of Algol 68 |
| ALGOL Y | ⊕ 1966 | ↓ ↑ ⊕ Numerical Scientific | True ALGOL68s | ⊕ International | First version of Algol 68 |
| EPOS ALGOL | ⊕ 1971 | ↓ ↑ ⊕ Numerical Scientific | True ALGOL68s | ||
| FLACC | ⊕ 1977 | ↓ ↑ ⊕ Multi-purpose | True ALGOL68s | ⊕ Canada | Mailloux's Algol 68 |
| Generalized ALGOL | ⊕ 1962 | ↓ ↑ ⊕ Numerical Scientific | True ALGOL68s | ⊕ Netherlands | ALGOL for generalised grammars |
| RS Algol | ⊕ 1979 | ↓ ↑ ⊕ Numerical Scientific | True ALGOL68s | ⊕ United Kingdom |