Generate chess diagrams in Node.

npm install
npm run start

Open your browser and enter this sample URL:

http://localhost:3000/diagram?fen=2r3k1/p4p2/3Rp2p/1p2P1pK/8/1P4P1/P3Q2P/1q6&inline=1&size=400

Send parameters as a query string:

• fen = FEN string for the diagram
• size = size of the diagram (100 to 1000 pixels)
• rev = set 1 to true if you want the board to be reversed (black pieces at the bottom)
• inline = set to 1 to display the image, default will download it

A bit more complex code is being used by SparkChess, an online chess app, to generate and download chess diagrams.

You can find more details about the code in this article.

I also created a PHP version of this code.