Open source web-based tool for schematics and circuits

I am currently working on a project where I am supposed to have several ethernet uC's that send TCP/UDP packets to a PC/Rpi and then are forwarded to other devices depending on which configuration is set.

How do I make such configuration? I am looking for a web-based tool where you are supposed to add a 'block' for a source, assign an IP and then add a 'block' for a destination and simply draw a line between them

The closest I can find are schematic web tools to draw circuits: All of them have the same principle, add several devices and connect them with lines.

I found several, like:

• http://ift.tt/Ah24hj
• http://ift.tt/1OmXs6m
• http://ift.tt/1dB02Ss
• http://ift.tt/2bqjRCa
• http://ift.tt/1ug1zXJ

They all look cool, but all of them are paid and closed source. Questions:

1. Do you know if there is any open source of something similar?
2. What language do you advise? Javascript (Im a newbie btw)
3. Do you advise any library to use? Canvas-based? Vector-based? (i should be able to save/load and convert the connections to some text file that would be interpreted by my project app)