TLV Parser

What is TLV (Tag-Length-Value)?

TLV (Tag-Length-Value) is the binary data-encoding scheme that powers EMV chip card communication, ISO 7816 smart cards, and the vast majority of contactless payment protocols. Each data element is encoded as three back-to-back fields: a Tag identifying the semantic meaning of the data, a Length specifying how many bytes the value occupies, and the Value containing the actual bytes. This format is self-describing and extensible — a parser that does not recognize a tag can still skip it cleanly using the Length field. The EMV specifications (originally Europay, Mastercard, Visa; now maintained by EMVCo with American Express, Discover, JCB, UnionPay) define hundreds of tags spanning card authentication, transaction processing, terminal risk management, and issuer-to-card script commands. Tags fall into two classes: primitive tags carry raw data directly (e.g., tag 5A is the Application PAN), while constructed tags are containers whose value field is itself a sequence of nested TLV objects (e.g., tag 70 is the Application Proprietary Template that wraps several primitives). Tags can be one or two bytes; lengths can be one byte (≤127) or use BER encoding for longer values. Our parser handles all variants automatically and resolves tag names from the full EMV tag dictionary.

How to Use This Tool

1. Paste EMV TLV hex data from a card reader, transaction log, EMV script, or HSM response.
2. The parser identifies each tag using the comprehensive EMV tag dictionary (EMV Book 3 + scheme-specific extensions).
3. Nested (constructed) tags are automatically expanded to show their child elements in a tree view.
4. View tag names, descriptions, lengths, and raw HEX values side-by-side for each element.
5. Click any tag to copy its raw value for use in HSM commands or test fixtures.
6. Use the parser output as documentation when filing certification evidence with payment networks.

Common Use Cases

• Parsing EMV chip card responses from SELECT, GET PROCESSING OPTIONS, READ RECORD, and GENERATE AC commands.
• Decoding Application Cryptograms (ARQC, TC, AAC) and the related Cryptogram Information Data (CID) byte.
• Analyzing TLV captured from EMV contactless flows (Visa qVSDC, Mastercard PayPass, AMEX ExpressPay).
• Verifying EMV script commands (PUT DATA, APPLICATION BLOCK, UNBLOCK PIN) before personalization.
• Debugging Track 2 Equivalent Data (tag 57) and Application PAN (tag 5A) extraction in acquirer integrations.
• Reading issuer scripts returned from authorization hosts (tag 71 / 72) to confirm card-management updates.
• Validating TLV produced by HSM Thales payShield commands (HC, GE, IE) during testing.
• Educating new EMV engineers on tag semantics and constructed-vs-primitive distinctions.

Worked Example: Decoding a GENERATE AC Response

Below is a typical Format 2 response from a GENERATE AC command — the moment the chip returns its ARQC during an online authorization. Tag 77 is constructed, so its value is itself a sequence of TLV objects:

Input:
771E9F2701809F3602003C9F26088A1B2C3D4E5F60719F100706010A03A00000

Decoded:
77       Response Message Template Format 2   (constructed, 30 bytes)
├─ 9F27  Cryptogram Information Data          80                → ARQC requested
├─ 9F36  Application Transaction Counter      003C              → ATC = 60
├─ 9F26  Application Cryptogram               8A1B2C3D4E5F6071
└─ 9F10  Issuer Application Data              06010A03A00000

EMV Tags Quick Reference

The tags you will meet in almost every EMV transaction log. Paste any of them into the parser above, or browse the complete dictionary with formats and full descriptions in the EMV Tag Dictionary & Decoder.

Frequently Asked Questions