Clasp 2.0
github.com
github.com
SBCL: very active
LispWorks: very active
Allegro: very active
ECL: active. Bus factor of two! \o/
CCL: needs more love. Some are ready to financially support a port to the M1. See the CL Foundation.
CLISP: somewhat active, no releases in a long time.
ABCL (on the JVM): looks good, a new release in preparation?
Corman Lisp (for Windows): made open-source a few years ago.
and:
Coalton: Haskell-like types on top of SBCL.
the new SICL: parts are used in Clasp.
more:
NPT is a new implementation in C in the making.
>NPT is a new implementation in C in the making.
NPT vs ECL?
CMUCL
JSCL
> I thought SBCL was its considered its successor.
Generally SBCL has a lot of advantages, incl. being available on current 64bit platforms. The typical developer will very likely better use SBCL.
It's not unusual though that some out-of-fashion Lisp implementations are still maintained by a small group - as long as there is enough knowhow available. Clozure CL for example currently has the problem that some people would like to use it, but it has not the necessary maintainer with the needed low-level knowhow. A problem is for example to get a native port to the Apple Silicon Macs done. Something which was done for SBCL quite some time ago.
There's no relation to CLISP. There's a brief history on the home page; it started out as Kyoto Common Lisp in '84, then William Schelter took it up to support his work on GNU Maxima.