Vin and fendertag decoder
There's a reason 'good' decoders don't already exist.
What was coded, when it was coded and even where it was coded changes year to year, plant to plant and even within the model year. An accurate decoders would have to be done for every plant for every year.
It's is almost impossible to account for tag nuances via an online decoder that lacks if/then as well as and/or logical functions as well as intelligent experience.
What may be correct for an 'early' car may be incorrect for a 'late' car. Online decoders do not account for the SPD time function of coding.
What applies at one plant may not apply at another plant. On line decoders need to be able to account for this and don't. Different plants have different layouts.
Most decoders are designed to simply return info already listed in the data base. If you have Garbage in you get garbage out. Weird coding quirks exist that would be difficult for a non-intelegent entity to determine, decode and explain.
Online decoders can't spot bad/fake tags
So while more cumbersome and time consuming, personal decodes are still the most complete and accurate.