Fetch Data via SDK

You can use the Aptos client to retrieve on-chain data using a variety of helper methods. The examples below assume you have already created an Aptos client instance:

use aptos_sdk::{Aptos, AptosConfig};

let aptos = Aptos::new(AptosConfig::testnet())?;

Account Balances

Fetch the APT balance for any account address. The balance is returned in octas (1 APT = 100,000,000 octas).

let address = "0x1".parse()?;
let balance = aptos.get_balance(address).await?;
println!("Balance: {} octas", balance);

Account Information

Check whether an account exists on-chain and retrieve its current sequence number. The sequence number is needed when building transactions manually.

let address = "0x1".parse()?;

// Check if an account exists
let exists = aptos.account_exists(address).await?;
println!("Account exists: {}", exists);

// Get the current sequence number
let sequence_number = aptos.get_sequence_number(address).await?;
println!("Sequence number: {}", sequence_number);

Ledger Info

Retrieve the current state of the blockchain, including the latest ledger version, block height, and epoch.

let info = aptos.ledger_info().await?;
println!("Ledger version: {}", info.ledger_version);
println!("Block height: {}", info.block_height);
println!("Epoch: {}", info.epoch);

View Functions (JSON)

View functions let you call on-chain Move functions that are marked as #[view] without submitting a transaction. The JSON variant returns results as serde_json::Value, which is useful for quick lookups and dynamic data.

No type arguments

Call a simple view function with no type arguments or parameters:

let result = aptos
    .view("0x1::timestamp::now_seconds", vec![], vec![])
    .await?;
println!("Current timestamp: {:?}", result);

With type arguments

To query a specific coin balance, pass the coin type as a type argument and the account address as a function argument:

let result = aptos
    .view(
        "0x1::coin::balance",
        vec!["0x1::aptos_coin::AptosCoin"],
        vec![serde_json::json!("0x1")],
    )
    .await?;
println!("Coin balance: {:?}", result);

View Functions (BCS)

The view_bcs method returns results as BCS-encoded bytes, which you can deserialize into strongly typed Rust structs. This is more efficient and type-safe than the JSON variant.

let timestamp: Vec<u64> = aptos
    .view_bcs("0x1::timestamp::now_seconds", vec![], vec![])
    .await?;
println!("Current timestamp: {} seconds", timestamp[0]);

Tip

Use view_bcs when you know the return type at compile time and want to avoid manually parsing JSON. Use view when working with dynamic or unknown return types.

Gas Estimation

Estimate the gas cost of a transaction before submitting it. This is helpful for displaying fee estimates to users or validating that a transaction will not exceed a gas budget.

use aptos_sdk::types::InputEntryFunctionData;

let payload = InputEntryFunctionData {
    function: "0x1::aptos_account::transfer".to_string(),
    type_arguments: vec![],
    arguments: vec![
        serde_json::json!("0xrecipient_address"),
        serde_json::json!("1000"),
    ],
};

let gas_estimate = aptos.estimate_gas(&sender, payload.clone()).await?;
println!("Estimated gas units: {}", gas_estimate);

Fullnode REST Client

For advanced queries not covered by the high-level Aptos methods, you can access the fullnode REST client directly. This gives you access to the complete set of fullnode API endpoints.

let address = "0x1".parse()?;

// Retrieve all modules published under an account
let modules = aptos.fullnode().get_account_modules(address).await?;
for module in &modules.data {
    println!("Module: {}", module.abi.as_ref().unwrap().name);
}

Note

The fullnode client exposes methods that map directly to the Aptos fullnode REST API. Use it when you need access to endpoints such as get_account_resources, get_transactions, or get_block_by_height.

Indexer Queries

The SDK includes an indexer client for querying aggregated and enriched on-chain data. The indexer provides access to data types that are not available through the fullnode API alone, such as token ownership history, event aggregations, and account transaction summaries.

let indexer = aptos.indexer();

Caution

The indexer client requires the indexer feature flag to be enabled in your Cargo.toml. This feature is included in the default feature set but must be explicitly enabled if you are using default-features = false.

The indexer client provides access to:

• Token data — ownership, metadata, and transfer history for digital assets.
• Coin balances — current and historical balances across all coin types.
• Account transactions — enriched transaction data with decoded payloads.
• Event data — aggregated and filterable event streams.
• Collection data — NFT collection metadata and statistics.

Note

Indexer data may lag slightly behind the latest ledger version because it requires additional processing. If you need the freshest data, query the fullnode client or use ledger version parameters where available.