# Fuel
> Fuel API is available on [Web3 API platform](https://crypto-chief.com/rpc/fuel/).
*Fuel* is a modular execution layer and high-performance rollup platform built around the FuelVM — a UTXO-based virtual machine designed for parallel transaction execution. Unlike EVM rollups, FuelVM uses predicates and scripts (UTXO unlocking conditions) rather than an account-state model, enabling native parallelism without conflicts. Fuel targets high-throughput use cases where the EVM's sequential execution model creates bottlenecks.
The node exposes a [JSON-RPC](https://www.jsonrpc.org/specification) interface along with a GraphQL API for richer data queries.
### Queries/Mutations supported
* [getAddressAssetBalance](#getaddressassetbalance) — retrieves the balance of a specific asset of a given address.
* [getAddressAssetBalances](#getaddressassetbalances) — retrieves balances of all assets of a given address.
* [getTransactionsByOwner](#gettransactionsbyowner) — retrieves all transactions of a given address.
* [getLatestTransactions](#getlatesttransactions) — retrieves the most recent transactions on the network.
* [getContractAssetBalance](#getcontractassetbalance) — retrieves the balances of a specific asset of a given contract.
* [getContractAssetBalances](#getcontractassetbalances) — retrieves all asset balances of a given contract.
* [getLatestBlocks](#getlatestblocks) — retrieves several most recent blocks on the network.
* [getLatestBlock](#getlatestblock) — retrieves the most recent block on the network.
* [getBlockByHeight](#getblockbyheight) — retrieves info on a block specified by height.
* [getBlockById](#getblockbyid) — retrieves info on a block specified by ID.
* [getMessagesByAddress](#getaddressassetbalance) — retrieves all messages of a given address.
* [dryRunTransaction](#dryruntransaction) — simulates a transaction without broadcasting it.
* [submitTransaction](#submittransaction) — submits a transaction to the network.
***
### `getAddressAssetBalance`
> Returns the asset balance (including CKB and UDT tokens) for the given CKB address.
#### Parameters
* `address` (string; required): an address of an externally owned account identified by a 32 byte string prefixed by `0x`.
* `assetId` (string; required): a 32 byte unique ID used to identify a coin.
#### Returns
* `data` (object): contains the query result.
* `balance` (object): represents the balance for the specified address and asset.
* `owner` (string): the address that owns the balance returned.
* `amount` (string): the amount of the asset held by the address.
* `assetId` (string): the asset ID for the queried asset.
#### Request example
```bash
curl --location 'https://rpc.crypto-chief.com/fuel/{YOUR_API_KEY}' \
--header 'Accept: application/json' \
--header 'Content-Type: application/json' \
--data '{
"query": "query Balance($address: Address, $assetId: AssetId) { balance(owner: $address, assetId: $assetId) { owner amount assetId } }",
"variables": {
"address": "0xce9f8d9367fc4671c0ececce7ab603f6f75d1e66082a82ad12ecdc219b308820",
"assetId": "0x2a0d0ed9d2217ec7f32dcd9a1902ce2a66d68437aeff84e3a3cc8bebee0d2eea"
}
}'
```
#### Response example
```json
{
"data": {
"balance": {
"owner": "0xce9f8d9367fc4671c0ececce7ab603f6f75d1e66082a82ad12ecdc219b308820",
"amount": "0",
"assetId": "0x2a0d0ed9d2217ec7f32dcd9a1902ce2a66d68437aeff84e3a3cc8bebee0d2eea"
}
}
}
```
***
### `getAddressAssetBalances`
> Returns asset balances for multiple CKB addresses in a single request.
#### Parameters
* `filter` (object; required): the filter object to query balances.
* `owner` (string; required): an address of an externally owned account identified by a 32 byte string prefixed by `0x`.
#### Returns
* `data` (object): contains the query result.
* `balance` (object): represents the balance details of the provided address based on the filter applied
* `nodes` (array): an array of balance entries (up to 5 in this case, based on first: 5). Each object contains information about a balance for a specific asset.
* `amount` (string): the amount of the asset associated with the address.
* `assetId` (string): the asset ID for the specific asset the balance is associated with.
#### Request example
```bash
curl --location 'https://rpc.crypto-chief.com/fuel/{YOUR_API_KEY}' \
--header 'Accept: application/json' \
--header 'Content-Type: application/json' \
--data '{
"query": "query Balances($filter: BalanceFilterInput) { balances(filter: $filter, first: 5) { nodes { amount assetId } } }",
"variables": {
"filter": {
"owner": "0xce9f8d9367fc4671c0ececce7ab603f6f75d1e66082a82ad12ecdc219b308820"
}
}
}'
```
#### Response example
```json
{
"data": {
"balances": {
"nodes": [
{
"amount": "1000000000000000000",
"assetId": "0xAssetIdHere"
},
{
"amount": "2000000000000000000",
"assetId": "0xAnotherAssetIdHere"
}
]
}
}
}
```
***
### `getTransactionsByOwner`
> Returns transactions associated with the given address or lock script owner.
#### Parameters
* `address` (string; required): the address to fetch the transactions for.
#### Returns
* `data` (object): contains the query result.
* `transactionsByOwner` (object): contains the transactions related to the provided address. It is an object with the following properties:
* `nodes` (array): an array of transactions, with each transaction containing information about inputs, outputs, and status.
* `id` (string): the transaction identifier.
* `inputs` (array): a list of inputs to the transaction:
* `__typename` (string): a specific type of input in the transaction.
* `owner` (string): the owner of the coin input (address).
* `utxoId` (string): the ID of the unspent transaction output (UTXO).
* `amount` (string): the amount of the asset involved in the transaction.
* `assetId` (string): the unique identifier of the asset involved in the transaction.
* `outputs` (array): an array of outputs, representing the transaction destination.
* `__typename` (string): a specific type of output in the transaction.
* `to` (string): the transaction destination address.
* `amount` (string): the amount of the asset involved in the transaction.
* `assetId` (string): the unique identifier of the asset involved in the transaction.
* `status` (object): the transaction status.
* `__typename` (string): the status name.
#### Request example
```bash
curl --location 'https://rpc.crypto-chief.com/fuel/{YOUR_API_KEY}' \
--header 'Accept: application/json' \
--header 'Content-Type: application/json' \
--data '{
"query": "query Transactions($address: Address) { transactionsByOwner(owner: $address, first: 5) { nodes { id inputs { __typename ... on InputCoin { owner utxoId amount assetId } ... on InputContract { utxoId contractId } ... on InputMessage { sender recipient amount data } } outputs { __typename ... on CoinOutput { to amount assetId } ... on ContractOutput { inputIndex balanceRoot stateRoot } ... on ChangeOutput { to amount assetId } ... on VariableOutput { to amount assetId } ... on ContractCreated { contract stateRoot } } status { __typename ... on FailureStatus { reason programState { returnType } } } } } }",
"variables": {
"address": "0xf65d6448a273b531ee942c133bb91a6f904c7d7f3104cdaf6b9f7f50d3518871"
}
}'
```
#### Response example
```json
{
"data": {
"transactionsByOwner": {
"nodes": [
{
"id": "0x670dde2a38d1bcd055aff7dfde5ed4c8f7532002dd0a9740f1b8732981c575be",
"inputs": [
{
"__typename": "InputCoin",
"owner": "0x33d25d8d874c0eb5933f9ca505a172725aa19c65bd707ce7c1e7917b483bda16",
"utxoId": "0x00c38d75412b7835947c8fde5f6d1f892488687c5a030bafe058b97a253766c60000",
"amount": "2000000",
"assetId": "0xf8f8b6283d7fa5b672b530cbb84fcccb4ff8dc40f8176ef4544ddb1f1952ad07"
}
],
"outputs": [
{
"__typename": "CoinOutput",
"to": "0xf65d6448a273b531ee942c133bb91a6f904c7d7f3104cdaf6b9f7f50d3518871",
"amount": "160000",
"assetId": "0xf8f8b6283d7fa5b672b530cbb84fcccb4ff8dc40f8176ef4544ddb1f1952ad07"
},
{
"__typename": "ChangeOutput",
"to": "0x33d25d8d874c0eb5933f9ca505a172725aa19c65bd707ce7c1e7917b483bda16",
"amount": "1715889",
"assetId": "0xf8f8b6283d7fa5b672b530cbb84fcccb4ff8dc40f8176ef4544ddb1f1952ad07"
}
],
"status": {
"__typename": "SuccessStatus"
}
}
]
}
}
}
```
***
### `getLatestTransactions`
> Returns a list of the most recently confirmed transactions.
#### Parameters
None.
#### Returns
* `data` (object): contains the query result.
* `transactions` (object): the transaction object with the following properties:
* `nodes` (array): an array of transactions, with each transaction containing information about inputs, outputs, and status.
* `id` (string): the transaction identifier.
* `inputs` (array): a list of inputs to the transaction:
* `__typename` (string): a specific type of input in the transaction.
* `owner` (string): the owner of the coin input (address).
* `utxoId` (string): the ID of the unspent transaction output (UTXO).
* `amount` (string): the amount of the asset involved in the transaction.
* `assetId` (string): the unique identifier of the asset involved in the transaction.
* `outputs` (array): an array of outputs, representing the transaction destination.
* `__typename` (string): a specific type of output in the transaction.
* `to` (string): the transaction destination address.
* `amount` (string): the amount of the asset involved in the transaction.
* `assetId` (string): the unique identifier of the asset involved in the transaction.
* `status` (object): the transaction status.
* `__typename` (string): the status name.
#### Request example
```bash
curl --location 'https://rpc.crypto-chief.com/fuel/{YOUR_API_KEY}' \
--header 'Accept: application/json' \
--header 'Content-Type: application/json' \
--data '{
"query": "query LatestTransactions { transactions(last: 5) { nodes { id inputs { __typename ... on InputCoin { owner utxoId amount assetId } ... on InputContract { utxoId contractId } ... on InputMessage { sender recipient amount data } } outputs { __typename ... on CoinOutput { to amount assetId } ... on ContractOutput { inputIndex balanceRoot stateRoot } ... on ChangeOutput { to amount assetId } ... on VariableOutput { to amount assetId } ... on ContractCreated { contract stateRoot } } status { __typename ... on FailureStatus { reason programState { returnType } } } } } }"
}'
```
#### Response example
```json
{
"data": {
"transactions": {
"nodes": [
{
"id": "0x330d0c4fb7d1c8dda917906ff2c87097b92bdf3be67b1c2fb03a4ad1fe0cd9a0",
"inputs": null,
"outputs": [],
"status": {
"__typename": "SuccessStatus"
}
},
{
"id": "0x4ece83232f7b818e484546414cf6d8ffe98a61691602f4a34e9ed8b9bcf2b1d2",
"inputs": [
{
"__typename": "InputContract",
"utxoId": "0x8cbd7f0a0e01cd848ef95b1702c70e07bc509d7461375be959358a9ea9cb4e280000",
"contractId": "0x2e40f2b244b98ed6b8204b3de0156c6961f98525c8162f80162fcf53eebd90e7"
},
{
"__typename": "InputCoin",
"owner": "0x4526bf524620d52a5f2046ca4835f84bcc81a8359172dbd13995367d61adb08b",
"utxoId": "0x76766650603cb2146f48a7ee6a42215b91b0e48df2565e7598e42826e5b915b70001",
"amount": "296940893153",
"assetId": "0x1d5d97005e41cae2187a895fd8eab0506111e0e2f3331cd3912c15c24e3c1d82"
}
],
"outputs": [
{
"__typename": "ContractOutput",
"inputIndex": "0",
"balanceRoot": "0x0000000000000000000000000000000000000000000000000000000000000000",
"stateRoot": "0x0000000000000000000000000000000000000000000000000000000000000000"
},
{
"__typename": "VariableOutput",
"to": "0x4526bf524620d52a5f2046ca4835f84bcc81a8359172dbd13995367d61adb08b",
"amount": "10906889",
"assetId": "0xf8f8b6283d7fa5b672b530cbb84fcccb4ff8dc40f8176ef4544ddb1f1952ad07"
}
],
"status": {
"__typename": "SuccessStatus"
}
}
]
}
}
}
```
***
### `getContractAssetBalance`
> Returns the token balance held at a given CKB script (contract) address.
#### Parameters
* `contract` (string; required): the contract address to fetch the balance for.
* `asset` (string: required): the unique identifier of an asset to fetch the balance for.
#### Returns
* `data` (object): the data object with the following fields:
* `contractBalance` (object): the object containing details on the contract's balance for a specific asset:
* `contract` (string): the ID of the contract.
* `amount` (string): the balance amount of the asset in the contract.
* `assetId` (string): the unique identifier of the asset associated with the contract.
#### Request example
```bash
curl --location 'https://rpc.crypto-chief.com/fuel/{YOUR_API_KEY}' \
--header 'Accept: application/json' \
--header 'Content-Type: application/json' \
--data '{
"query": "query ContractBalance($contract: ContractId, $asset: AssetId) { contractBalance(contract: $contract, asset: $asset) { contract amount assetId } }",
"variables": {
"contract": "0x7777777777777777777777777777777777777777777777777777777777777777",
"asset": "0x2a0d0ed9d2217ec7f32dcd9a1902ce2a66d68437aeff84e3a3cc8bebee0d2eea"
}
}'
```
#### Response example
```json
{
"data": {
"contractBalance": {
"contract": "0x7777777777777777777777777777777777777777777777777777777777777777",
"amount": "0",
"assetId": "0x2a0d0ed9d2217ec7f32dcd9a1902ce2a66d68437aeff84e3a3cc8bebee0d2eea"
}
}
}
```
***
### `getContractAssetBalances`
> Returns token balances held at multiple CKB script addresses.
#### Parameters
* `filter` (object; required): the filter object used to query balances.
* `contract` (string; required): the contract address for which the asset balances is to be fetched.
#### Returns
* `data` (object): the data object which contains the following fields:
* `contractBalances` (object): the object containing details on the contract's balance for a specific asset.
* `nodes` (array): an array of balance records for different assets.
* `amount` (string): the balance amount of the specified asset in the contract.
* `assetId` (string): the unique identifier of the asset associated with the balance.
#### Request example
```bash
curl --location 'https://rpc.crypto-chief.com/fuel/{YOUR_API_KEY}' \
--header 'Accept: application/json' \
--header 'Content-Type: application/json' \
--data '{
"query": "query ContractBalances($filter: ContractBalanceFilterInput!) { contractBalances(filter: $filter, first: 5) { nodes { amount assetId } } }",
"variables": {
"filter": {
"contract": "0xf5b08689ada97df7fd2fbd67bee7dea6d219f117c1dc9345245da16fe4e99111"
}
}
}'
```
#### Response example
```json
{
"data": {
"contractBalances": {
"nodes": [
{
"amount": "0",
"assetId": "0x0000000000000000000000000000000000000000000000000000000000000000"
},
{
"amount": "7661229750000",
"assetId": "0x2a0d0ed9d2217ec7f32dcd9a1902ce2a66d68437aeff84e3a3cc8bebee0d2eea"
},
{
"amount": "0",
"assetId": "0xf8f8b6283d7fa5b672b530cbb84fcccb4ff8dc40f8176ef4544ddb1f1952ad07"
}
]
}
}
}
```
***
### `getLatestBlocks`
> Returns a list of the most recently produced blocks.
#### Parameters
None.
#### Returns
* `data` (object): the data object with the following fields:
* `blocks` (object): the blocks object with the following fields:
* `nodes` (array): an array with individual block records.
* `id` (string): the unique identifier of a block.
* `transactions` (array): an array representing the transactions within the block.
* `id` (string): the unique identifier of a transaction.
* `inputAssetIds` (array): an array of asset IDs used as inputs in the transaction.
* `inputs` (array): an array of the inputs used in the transaction.
* `__typename` (string): the specific type of input in the transaction.
* `owner` (string): the address that owned the input in the transaction.
* `utxoId` (string): the unique identifier for the unspent transaction output (UTXO) related to the input.
* `amount` (string): the amount of the asset in the transaction.
* `assetId` (string): the unique identifier of the asset in the transaction.
* `outputs` (array): an array of outputs, representing where the transaction destination.
* `__typename` (string): the specific type of output in the transaction.
* `inputIndex` (string): the index of the input that this contract output is associated with.
* `balanceRoot` (string): the root hash representing the contracts balance state.
* `stateRoot` (string): the root hash representing the contracts overall state.
* `to` (string): the destination address of the transaction.
* `amount` (string): the amount of the asset in the transaction.
* `assetId` (string): the unique identifier of the asset in the transaction.
#### Request example
```bash
curl --location 'https://rpc.crypto-chief.com/fuel/{YOUR_API_KEY}' \
--header 'Accept: application/json' \
--header 'Content-Type: application/json' \
--data '{
"query": "query LatestBlocks { blocks(last: 5) { nodes { id transactions { id inputAssetIds inputs { __typename ... on InputCoin { owner utxoId amount assetId } ... on InputContract { utxoId contractId } ... on InputMessage { sender recipient amount data } } outputs { __typename ... on CoinOutput { to amount assetId } ... on ContractOutput { inputIndex balanceRoot stateRoot } ... on ChangeOutput { to amount assetId } ... on VariableOutput { to amount assetId } ... on ContractCreated { contract stateRoot } } } } } }"
}'
```
#### Response example
```json
{
"data": {
"blocks": {
"nodes": [
{
"id": "0xfc309ad1b32896287ffb19de63d49242d9f7eb7f067b9397d2e9cda134241bfc",
"transactions": [
{
"id": "0x5749b555b9e4c89e453d08395e0b291df8b4a1b8235ca5440cd3701f6c11aa22",
"inputAssetIds": null,
"inputs": null,
"outputs": []
}
]
},
{
"id": "0x52a868e1b13afecf51ef2161663011c9f3865381316fc568aaa209ff41ee35aa",
"transactions": [
{
"id": "0x1078a8d9fc64a08a75ee2a20329bf98ad2cdafa340726e5184424709a6c25841",
"inputAssetIds": null,
"inputs": null,
"outputs": []
}
]
}
]
}
}
}
```
***
### `getLatestBlock`
> Returns the latest committed block from the Fuel node.
#### Parameters
None.
#### Returns
* `data` (object): the data object with the following fields:
* `chain` (object): the object representing the blockchain network info:
* `latestBlock` (object): the object containing details of the latest block on the network.
* `id` (string): the unique identifier (hash) of the latest block.
* `height` (string): the block height of the latest block.
#### Request example
```bash
curl --location 'https://rpc.crypto-chief.com/fuel/{YOUR_API_KEY}' \
--header 'Accept: application/json' \
--header 'Content-Type: application/json' \
--data '{
"query": "{ chain { latestBlock { id height } } }"
}'
```
**Response example**
```json
{
"data": {
"chain": {
"latestBlock": {
"id": "0x1cd6d6725bb58123623e8a60de42f269252dbf0df8922e27e45b9e894bffeea7",
"height": "13781885"
}
}
}
}
```
***
### `getBlockByHeight`
> Returns the full block at the specified height including header, transactions, and uncles.
#### Parameters
* `height` (string; required): the height of the block.
#### Returns
* `data` (object): the data object with the following fields:
* `block` (object): the object with the queried block info.
* `id` (string): the unique identifier (hash) of the block.
#### Request example
```bash
curl --location 'https://rpc.crypto-chief.com/fuel/{YOUR_API_KEY}' \
--header 'Accept: application/json' \
--header 'Content-Type: application/json' \
--data '{
"query": "query Block($height: U64) { block(height: $height) { id } }",
"variables": {
"height": "3000"
}
}'
```
#### Response example
```json
{
"data": {
"block": {
"id": "0xe4f573c8ba98085d8006d64176587720f166e761558a6f13fb40ad884d5db52c"
}
}
}
```
***
### `getBlockById`
> Returns block data for the block identified by the given hash.
#### Parameters
* `id` (string; required): a unique hash identifier for a block.
#### Returns
* `data` (object): the data object with the following fields:
* `block` (object): the object representing a specific block info.
* `id` (string): the unique identifier (hash) of the block.
* `height` (string): the height of the block.
* `transactions` (array): an array of transactions included in the block.
* `id` (string): the unique identifier (hash) of each transaction in the block.
#### Request example
```bash
curl --location 'https://rpc.crypto-chief.com/fuel/{YOUR_API_KEY}' \
--header 'Accept: application/json' \
--header 'Content-Type: application/json' \
--data '{
"query": "query BlockById($id: BlockId!) { block(id: $id) { id height transactions { id } } }",
"variables": {
"id": "0xe4f573c8ba98085d8006d64176587720f166e761558a6f13fb40ad884d5db52c"
}
}'
```
#### Response example
```json
{
"data": {
"block": {
"id": "0xe4f573c8ba98085d8006d64176587720f166e761558a6f13fb40ad884d5db52c",
"height": "3000",
"transactions": [
{
"id": "0x9dd04fce60b052963d8131c3e956a80e9a413363bae4f06a0ed0eeb575e24e0d"
}
]
}
}
}
```
***
### `getMessagesByAddress`
> Returns messages or transactions associated with the given CKB address.
#### Parameters
* `address` (string; required): the address to fetch the messages for.
#### Returns
* `data` (object): the data object with the following fields:
* `blocks` (object): the object representing the queried block info.
* `amount` (string): the amount of the message.
* `sender` (string): the address of the message sender.
* `recipient` (string): the address of the message destination.
* `nonce` (string): a unique identifier associated with the message.
* `data` (string): an optional additional data included in the message.
#### Request example
```bash
curl --location 'https://rpc.crypto-chief.com/fuel/{YOUR_API_KEY}' \
--header 'Accept: application/json' \
--header 'Content-Type: application/json' \
--data '{
"query": "query MessageInfo($address: Address) { messages(owner: $address, first: 5) { nodes { amount sender recipient nonce data daHeight } } }",
"variables": {
"address": "0xce9f8d9367fc4671c0ececce7ab603f6f75d1e66082a82ad12ecdc219b308820"
}
}'
```
#### Response example
```json
{
"data": {
"messages": {
"nodes": []
}
}
}
```
***
### `dryRunTransaction`
> Performs a dry-run of a transaction, returning effects and events without committing to the chain.
#### Parameters
* `encodedTransaction` (string: required): the hex-encoded transaction.
* `utxoValidation` (boolean; required): a UTXO validation selector.
#### Returns
* `data` (object): the data object with the following fields:
* `dryRun` (array): an array representing the simulated transaction result.
* `receiptType` (string): the type of receipt generated by the simulation.
* `data` (string): the hexadecimal data associated with the transaction outcome.
#### Request example
```bash
curl --location 'https://rpc.crypto-chief.com/fuel/{YOUR_API_KEY}' \
--header 'Accept: application/json' \
--header 'Content-Type: application/json' \
--data '{
"query": "mutation DryRun($encodedTransaction: HexString!, $utxoValidation: Boolean) { dryRun(tx: $encodedTransaction, utxoValidation: $utxoValidation) { receiptType data } }",
"variables": {
"encodedTransaction": "YOUR_ENCODED_TRANSACTION_HERE",
"utxoValidation": true
}
}'
```
***
### `submitTransaction`
> Submits a signed transaction to the network for processing.
#### Parameters
* `encodedTransaction` (string: required): the hex-encoded transaction.
#### Returns
* `data` (object): the data object with the following fields:
* `submit` (object): result of the submit mutation:
* `id` (string): the unique transaction ID generated upon transaction submission.
#### Request example
```bash
curl --location 'https://rpc.crypto-chief.com/fuel/{YOUR_API_KEY}' \
--header 'Accept: application/json' \
--header 'Content-Type: application/json' \
--data '{
"query": "mutation submit($encodedTransaction: HexString!) { submit(tx: $encodedTransaction) { id } }",
"variables": {
"encodedTransaction": "YOUR_ENCODED_TRANSACTION_HERE"
}
}'
```
---
# Agent Instructions: Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.
Perform an HTTP GET request on the current page URL with the `ask` query parameter:
```
GET https://docs-rpc.crypto-chief.com/chains/fuel.md?ask=
```
The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.
Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.