Run Forth-2012 in a sandbox: definitions stay between calls, each result shows the stacks.
Free
One server, in developer tools & repos. Run Forth-2012 in a sandbox: definitions stay between calls, each result shows the stacks.
Developer Tools & Repos
Run Forth-2012 in a sandbox: definitions stay between calls, each result shows the stacks.
The rest either hold an API key issued by the publisher or ask for nothing.
Listed without a verification tick. Read the listing before installing.