NBTLint

Quickly and easily validate the stringified NBT format (SNBT) used in Minecraft commands. Available on the web at https://www.soltoder.com/NBTLint/

Also available as a JavaScript library.

<script src="nbt-lint.js"></script>
<script>
    var tag1;
    try {
        tag1 = nbtlint.parse(input.value);
    } catch (e) {
        output.value = e.message;
    }
    
    var tag2 = new nbtlint.TagCompound({
        Score: new nbtlint.TagInteger(1500),
        Pos: new nbtlint.TagList(nbtlint.TagDouble, [
            new nbtlint.TagDouble(15.5),
            new nbtlint.TagDouble(123),
            new nbtlint.TagDouble(-491.77),
        ]),
        SelectedItem: new nbtlint.TagCompound({
            id: new nbtlint.TagString("minecraft:diamond_sword"),
        }),
    });
    console.log(nbtlint.stringify(tag2, "\t"));
    
// {
// 	Score: 1500,
// 	Pos: [15.5d, 123d, -491.77d],
// 	SelectedItem: {
// 		id: "minecraft:diamond_sword"
// 	}
// }
</script>