---
title: "getMempoolTransaction"
method: POST
path: "/mempool/transaction"
tags: ["Cardano - Rosetta"]
---

# getMempoolTransaction

`POST /mempool/transaction`

Get a transaction in the mempool by its Transaction Identifier. This is
a separate request than fetching a block transaction (/block/transaction)
because some blockchain nodes need to know that a transaction query is
for something in the mempool instead of a transaction in a block.

Transactions may not be fully parsable until they are in a block (ex: may
not be possible to determine the fee to pay before a transaction is
executed). On this endpoint, it is ok that returned transactions are
only estimates of what may actually be included in a block.

## Request body

- MempoolTransactionRequest — A MempoolTransactionRequest is utilized to retrieve a transaction from the mempool.
  - `network_identifier` NetworkIdentifier, required — The network_identifier specifies which network a particular object is associated with.
    - `blockchain` string, required
    - `network` string, required — If a blockchain has a specific chain-id or network identifier, it should go in this field. It is up to the client to determine which network-specific identifier is mainnet or testnet.
    - `sub_network_identifier` SubNetworkIdentifier — In blockchains with sharded state, the SubNetworkIdentifier is required to query some object on a specific shard. This identifier is optional for all non-sharded blockchains.
      - `network` string, required
      - `metadata` object
  - `transaction_identifier` TransactionIdentifier, required — The transaction_identifier uniquely identifies a transaction in a particular network and block or in the mempool.
    - `hash` string, required — Any transactions that are attributable only to a block (ex: a block event) should use the hash of the block as the identifier. This should be normalized according to the case specified in the transaction_hash_case in network options.

## Response `200`

Expected response to a valid request

- MempoolTransactionResponse — A MempoolTransactionResponse contains an estimate of a mempool transaction. It may not be possible to know the full impact of a transaction in the mempool (ex: fee paid).
  - `transaction` Transaction, required — Transactions contain an array of Operations that are attributable to the same TransactionIdentifier.
    - `transaction_identifier` TransactionIdentifier, required — The transaction_identifier uniquely identifies a transaction in a particular network and block or in the mempool.
      - `hash` string, required — Any transactions that are attributable only to a block (ex: a block event) should use the hash of the block as the identifier. This should be normalized according to the case specified in the transaction_hash_case in network options.
    - `operations` Operation[], required
      - `operation_identifier` OperationIdentifier, required — The operation_identifier uniquely identifies an operation within a transaction.
        - `index` integer, required — The operation index is used to ensure each operation has a unique identifier within a transaction. This index is only relative to the transaction and NOT GLOBAL. The operations in each transaction should start from index 0. To clarify, there may not be any notion of an operation index in the blockchain being described.
        - `network_index` integer — Some blockchains specify an operation index that is essential for client use. For example, Bitcoin uses a network_index to identify which UTXO was used in a transaction. network_index should not be populated if there is no notion of an operation index in a blockchain (typically most account-based blockchains).
      - `related_operations` OperationIdentifier[] — Restrict referenced related_operations to identifier indices < the current operation_identifier.index. This ensures there exists a clear DAG-structure of relations. Since operations are one-sided, one could imagine relating operations in a single transfer or linking operations in a call tree.
        - `index` integer, required — The operation index is used to ensure each operation has a unique identifier within a transaction. This index is only relative to the transaction and NOT GLOBAL. The operations in each transaction should start from index 0. To clarify, there may not be any notion of an operation index in the blockchain being described.
        - `network_index` integer — Some blockchains specify an operation index that is essential for client use. For example, Bitcoin uses a network_index to identify which UTXO was used in a transaction. network_index should not be populated if there is no notion of an operation index in a blockchain (typically most account-based blockchains).
      - `type` string, required — Type is the network-specific type of the operation. Ensure that any type that can be returned here is also specified in the NetworkOptionsResponse. This can be very useful to downstream consumers that parse all block data.
      - `status` string — Status is the network-specific status of the operation. Status is not defined on the transaction object because blockchains with smart contracts may have transactions that partially apply (some operations are successful and some are not). Blockchains with atomic transactions (all operations succeed or all operations fail) will have the same status for each operation. On-chain operations (operations retrieved in the `/block` and `/block/transaction` endpoints) MUST have a populated status field (anything on-chain must have succeeded or failed). However, operations provided during transaction construction (often times called "intent" in the documentation) MUST NOT have a populated status field (operations yet to be included on-chain have not yet succeeded or failed).
      - `account` AccountIdentifier — The account_identifier uniquely identifies an account within a network. All fields in the account_identifier are utilized to determine this uniqueness (including the metadata field, if populated).
        - `address` string, required — The address may be a cryptographic public key (or some encoding of it) or a provided username.
        - `sub_account` SubAccountIdentifier — An account may have state specific to a contract address (ERC-20 token) and/or a stake (delegated balance). The sub_account_identifier should specify which state (if applicable) an account instantiation refers to.
          - `address` string, required — The SubAccount address may be a cryptographic value or some other identifier (ex: bonded) that uniquely specifies a SubAccount.
          - `metadata` object — If the SubAccount address is not sufficient to uniquely specify a SubAccount, any other identifying information can be stored here. It is important to note that two SubAccounts with identical addresses but differing metadata will not be considered equal by clients.
        - `metadata` object — Blockchains that utilize a username model (where the address is not a derivative of a cryptographic public key) should specify the public key(s) owned by the address in metadata.
      - `amount` Amount — Amount is some Value of a Currency. It is considered invalid to specify a Value without a Currency.
        - `value` string, required — Value of the transaction in atomic units represented as an arbitrary-sized signed integer. For example, 1 BTC would be represented by a value of 100000000.
        - `currency` RpcCurrency, required — Currency is composed of a canonical Symbol and Decimals. This Decimals value is used to convert an Amount.Value from atomic units (Satoshis) to standard units (Bitcoins).
          - `symbol` string, required — Canonical symbol associated with a currency.
          - `decimals` integer, required — Number of decimal places in the standard unit representation of the amount. For example, BTC has 8 decimals. Note that it is not possible to represent the value of some currency in atomic units that is not base 10.
          - `metadata` object — Any additional information related to the currency itself. For example, it would be useful to populate this object with the contract address of an ERC-20 token.
        - `metadata` object
      - `coin_change` CoinChange — CoinChange is used to represent a change in state of a some coin identified by a coin_identifier. This object is part of the Operation model and must be populated for UTXO-based blockchains. Coincidentally, this abstraction of UTXOs allows for supporting both account-based transfers and UTXO-based transfers on the same blockchain (when a transfer is account-based, don't populate this model).
        - `coin_identifier` CoinIdentifier, required — CoinIdentifier uniquely identifies a Coin.
          - `identifier` string, required — Identifier should be populated with a globally unique identifier of a Coin. In Bitcoin, this identifier would be transaction_hash:index.
        - `coin_action` 'coin_created' | 'coin_spent', required — CoinActions are different state changes that a Coin can undergo. When a Coin is created, it is coin_created. When a Coin is spent, it is coin_spent. It is assumed that a single Coin cannot be created or spent more than once.
      - `metadata` object
    - `related_transactions` RelatedTransaction[]
      - `network_identifier` NetworkIdentifier — The network_identifier specifies which network a particular object is associated with.
        - `blockchain` string, required
        - `network` string, required — If a blockchain has a specific chain-id or network identifier, it should go in this field. It is up to the client to determine which network-specific identifier is mainnet or testnet.
        - `sub_network_identifier` SubNetworkIdentifier — In blockchains with sharded state, the SubNetworkIdentifier is required to query some object on a specific shard. This identifier is optional for all non-sharded blockchains.
          - `network` string, required
          - `metadata` object
      - `transaction_identifier` TransactionIdentifier, required — The transaction_identifier uniquely identifies a transaction in a particular network and block or in the mempool.
        - `hash` string, required — Any transactions that are attributable only to a block (ex: a block event) should use the hash of the block as the identifier. This should be normalized according to the case specified in the transaction_hash_case in network options.
      - `direction` 'forward' | 'backward', required — Used by RelatedTransaction to indicate the direction of the relation (i.e. cross-shard/cross-network sends may reference `backward` to an earlier transaction and async execution may reference `forward`). Can be used to indicate if a transaction relation is from child to parent or the reverse.
    - `metadata` object — Transactions that are related to other transactions (like a cross-shard transaction) should include the tranaction_identifier of these transactions in the metadata.
  - `metadata` object

## Other responses

- `500` — unexpected error

---

[API](https://skmtc.net/tatum/apis/blockchain-data.md) · [All operations](https://skmtc.net/tatum/apis/blockchain-data/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/tatum/blockchain-data/versions/8622ee4b8fae/schema)