FIX versions

This reference and the decoder cover two dictionary versions. Both are shipped as npm packages and both run in the browser.

FIX 4.4912 fields · 93 messages · 105 components FIX 4.2405 fields · 46 messages · 2 components

Which one am I looking at?

Read BeginString, tag 8 — it is the first field of every message. The decoder does this automatically. See FIX 4.4 vs FIX 4.2 for what actually differs.