CodePicnic is described as 'helps developers and companies to offer embeddable, sandboxed, real-time containers with a single line of code' and is an website in the Development category. There are four alternatives to CodePicnic, not only websites but also apps for Self-Hosted solutions and SaaS. The best alternative is AWS Cloud9. It's not free, so if you're looking for a free alternative, you could try Ideone or SLAppForge.
AWS Cloud9 is a code editor and development environment built with browser technology yet with the power of a desktop IDE. It's available both as an online service and as a locally hosted platform. FEATURES - Full featured Linux terminal built in.