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Stuck on a tag, a TVR or a certification step? Send us your question. We reply by email, and useful answers become guides on the blog.
Common questions
Is it safe to paste card data into your tools?
Our tools run entirely in your browser and send nothing to a server. Even so, use test cards and test keys only. Never paste live card numbers, track data or production keys into any website.
Why does my TLV fail to parse?
The most common causes are a missing byte at the start or end of the copy, an odd number of hex digits, or a long length encoded as 81 or 82 that another tool mis-handled. The parser points to the byte where it stopped.
What is the difference between ARQC, TC and AAC?
They are the three cryptograms a card can return. ARQC asks for online authorisation, TC approves offline, and AAC declines. Tag 9F27 tells you which one the card returned.
Why is every transaction going online?
Usually the terminal floor limit is zero, which sets TVR byte 4 bit 8 on every transaction, and the online action codes include that bit. See TVR Explained.