The standard definitely limits what precision you should expect to be handled.
But how JSON numbers are handled by different parsers might surprise you. This blog post actually does a good job of detailing the subtleties and the choices made in a few standard languages and libraries: https://github.com/bterlson/blog/blob/main/content/blog/what...
I think one particular surprise is that C# and Java standard parsers both use openAPI schema hints that a piece of data is of type ‘number’ to map the value to a decimal floating point type, not a binary one.
>C# and Java standard parsers
Not sure which parser you consider standard, as Java doesn't have one at all (in the standard libraries). Other than that the existing ones just take the target type (not json) when they deserialize into, e.g. int, long, etc.
That blog post treats Jackson as the de facto standard Java JSON parser/formatter which seems reasonable.
That's bit much - (unfortunately) the codebase uses at least 4 different json libraries (perhaps 5 if I consider one non-general purpose, personally written). gson is generally very popular as well. The blog post mentions BigDecimal and at that point, I'd not dare to trust it much.
The de-facto standard is similar to the expectation everyone uses spring boot.