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What Is a Transaction ID (TXID)? How to Find and Use One

A transaction ID, or TXID, is the unique hash of a transaction's data that identifies it on a blockchain, used to look it up in a block explorer and as the leaf entry in a block's merkle tree.

Key takeaways

What it is

Every transaction has an identifier made by hashing its serialised data. The result is a long string of hexadecimal characters, usually 64 of them. Because it is derived from the content, any change to the transaction produces a different TXID, and two transactions with different content cannot share one in practice. The TXID is how nodes, wallets and explorers refer to a specific transaction.

What you use it for

When a payment looks stuck or missing, the TXID is the exact reference you need. Paste it into a block explorer to see whether the transaction is unconfirmed, how many confirmations it has, which block it is in and where the coins went. Support teams also ask for it, because an address alone can match many payments while a TXID matches one.

How blocks use it

Inside a block, transactions are listed by their TXIDs. The Bitcoin developer documentation describes pairs of TXIDs being hashed together, row by row, to form the merkle root that goes in the block header. That is how a header commits to every transaction without listing them.

SegWit and malleability

Before Segregated Witness, parts of the signature data were included in the hash, and a third party could sometimes alter how a signature was encoded without changing its validity, which changed the TXID. BIP-141 moved signature data into a separate witness section and excluded it from the TXID, introducing a separate witness TXID (wtxid) that covers it. That makes involuntary changes to a transaction's ID impossible for the transactions it covers.

Example

You send coins and your wallet shows a 64-character TXID starting with 3f9a. Pasting it into a block explorer shows 'unconfirmed, 0 confirmations'. Twenty minutes later the same TXID shows block 2,650,000 and 4 confirmations.

Put it into practice

Look up any payment by its ID

Choose your preferred block explorer in Scrypt Wallet, then paste a TXID to check the confirmations and the block a payment landed in.

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Sources and verification

Last reviewed 2026-10-02 by the Scrypt Wallet team. The factual claims on this page, and where each comes from:

  1. The merkle tree is built by hashing pairs of TXIDs with SHA256(SHA256()), up to the merkle root in the block header. [1]
  2. BIP-141 excludes signature (witness) data from the transaction hash and defines a separate wtxid that includes it. [2]
  3. Because signature data is no longer part of the transaction hash, involuntary malleability due to signing changes is prevented. [2]

Sources

  1. Bitcoin developer reference: Block chain · Bitcoin.org · primary source
  2. BIP-141: Segregated Witness (consensus layer) · bitcoin/bips on GitHub · primary source

Primary sources are protocol papers, specifications, source code or a project's own documentation; secondary sources are wikis and explainers. We checked each claim against the source text on the review date. Found an error? Tell us and we will correct it.

Frequently asked questions

Is a TXID the same as my address?

No. An address says where coins can be received. A TXID identifies one specific transaction.

Can two transactions have the same TXID?

Not in practice. The ID is a hash of the transaction's content, so different transactions have different IDs.

Where do I find my TXID?

In your wallet's transaction details, and on the transaction's page in a block explorer.

Related terms

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Written by the Scrypt Wallet team · Updated 2026-10-02. General education, not financial, tax or legal advice.