List of free decoder stuff for developerππ½
If you're looking for all programming tools around decoder (not just free). Check this page List of decoder Programming Tools

SmallDev.tools
FREE tools for developers like encoder/decoder, HTML/CSS/Javascript formatters, minifiers, fake or test data generators & much more.
Tag: formatter, encoder, decoder, minifier, beautifier, dataset
Encode/Decode various formats Minify HTML/CSS/Javascript Beautifier Generate Fake/Testing real like dataset in JSON/CSV & multiple other formats

DevPal
DevPal is a set of many online developer tools that make developers' everyday work productve
Tag: url-encoder, text-editor, devtools, json, image, generator, encoder, decoder, formatter, productivity