Payment tools that run locally.

Parse EMV tag structures from Data Element 55. Supports constructed templates, tag dictionary, error offsets, JSON export.

Parse ISO 8583 messages (MTI + bitmap + fields). Built-in field table or custom JSON configs. DE 55 auto-expands to a TLV tree.

Tick data elements to build a bitmap, or paste one to see the fields it turns on. Hex, binary and field list stay in sync, and bit 1 is handled for you.

Fork the built-in field table, edit lengths, types and renderers with live validation, and test a message against it. Saved configs feed straight into the decoder.

Decode an X9.143 / TR-31 or Thales key block: header fields, optional blocks, and — with the protection key — MAC verification and the recovered key. Builds blocks too.

Validate a Luhn check digit, compute one for a number that has none, or generate valid numbers for test data. Works on PANs, ARNs and anything else mod-10.

Paste hex or text, or load a file, and read it as a classic hex dump with an ASCII column alongside. Paged, with jump-to-offset and a plain-text export.

Encode text, hex or a file to Base64, or decode Base64 back to text or hex. Standard and URL-safe alphabets, optional padding and line wrapping, and every input spelling accepted on decode.

Turn a run of hex into readable ASCII, or text into hex. Choose the byte delimiter and case, and see non-printable bytes as dots or \xNN escapes rather than lost characters.

Read the same bytes as UTF-8, UTF-16/32, Latin-1, Windows-1252 or EBCDIC (CP037/CP500) side by side, or encode text into any of them. Handy when a mainframe hands you EBCDIC and you need to know what it says.

Hash text, hex, Base64 or a file with MD5, SHA-1, SHA-2, SHA-3 or CRC32 — several at once, so two digests can be compared side by side. Keyed HMAC mode, and a field to check a digest you were given.

Encrypt and decrypt with DES, 2-/3-key 3DES and AES-128/192/256 in ECB or CBC, plus the checks payments key work needs: key check value, DES parity, CBC-MAC and the ANSI X9.19 Retail MAC. Keys and data as hex; everything anchored to NIST/X9 test vectors.

Derive the IPEK from a BDK and KSN, walk the KSN counter to this transaction's key, and split it into PIN, MAC and data working keys — with the full derivation trail shown, so the tool teaches the X9.24-1 algorithm rather than just printing an answer.

Search action and response codes across ISO 8583 DE 39, Visa, Mastercard, Amex, Discover and UPI. Filter by scheme, search by code or meaning, and see a provenance badge so unofficial codes are labelled rather than trusted blindly.