Code2flow is described as 'Code2Flow is an innovative diagram creator that uses simple programming structure to build flowcharts in the most intuitive way possible. It employs syntax from the C programming language in a way that makes it easily usable for non-programmers and programmers alike' and is an website in the Office & Productivity category. There are eight alternatives to Code2flow, not only websites but also apps for a variety of platforms, including Self-Hosted solutions, Mac, Windows and Linux. The best alternative is Graphviz, which is both free and Open Source. Other great sites and apps similar to Code2flow are DotEditor (Free, Open Source), Asciio (Free, Open Source), Flowchart.js (Free, Open Source) and textografo (Paid).
Graphviz is open source graph visualization software. It has several main graph layout programs. It also has web and interactive graphical interfaces, and auxiliary tools, libraries, and language bindings.
Asciio is a Perl application that allows you to draw ASCII diagrams in a modern (but simple) graphical interface. The ASCII graphs can be saved as ASCII or in a format that allows you to modify them later.