> ## Documentation Index
> Fetch the complete documentation index at: https://circle-devdocs-test-ai-codegen-component.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Transaction Rate Limits and Optimizations

In this guide, you’ll learn about the transaction rate limits imposed by
supported blockchains and Circle Wallets. You’ll also get client-side
optimization tips to ensure smooth transaction processing within your
applications.

## Transaction Queue Limits

### Blockchain Account Queue Limit

EVM-compatible blockchains typically use a Mempool system. The Mempool queues
transactions sent from a wallet up to a certain limit defined by the full node.
If you exceed this limit, you receive an error from the full node. All queued
transactions in the Mempool can potentially be included in a single block.
Therefore, you can estimate the theoretical transaction throughput as
`queueLimit` / `blockTime`. However, various factors can influence whether your
transaction gets included in a block, such as priority fees, network congestion,
and network liveness. In contrast, the Solana blockchain does not use a Mempool
system and, thus, does not have a queue limit. This contributes to its
transaction throughput being significantly higher.

#### Account queue limit in different blockchains

| Blockchain          | EOA wallet      | SCA wallet          |
| ------------------- | --------------- | ------------------- |
| Ethereum            | 32 transactions | 1 transaction       |
| Polygon             | 16 transactions | 1 transaction       |
| Avalanche           | 32 transactions | 1 transaction       |
| Solana (no Mempool) | Unlimited       | Not supported by PW |

#### Circle Wallets Transaction Queue Limit

The overall transaction throughput is fundamentally constrained by the
blockchain account queue limit and the blockchain's inherent throughput. To
mitigate the impact of these limitations, Circle Wallets provide a queuing
mechanism for transactions that exceed the blockchain limit for a certain
duration. There is a limit on the number of transactions your wallet can queue
in the Circle Wallets service to prevent resource wastage and false
expectations. This limit affects the user experience when too many transaction
requests are made. When you reach this limit, you receive an error message:

<Danger>
  "Wait for pending transactions to be included on the blockchain before
  submitting new requests. EVM chains restrict the number of queued transactions
  per sender address." (Error code 155264)
</Danger>

More detailed error descriptions and suggestions can be found in the
[Transaction error codes](/w3s/synchronous-errors#transaction-error-codes-155201---155299)
section.

To check the number of pending transactions and their status, use the
`listTransaction` API endpoint. The transaction state should be one of the
following: `INITIATED`, `CLEARED`, `QUEUED`, `SENT`.

## Client-side Optimizations

While transaction queuing provides a convenient feature, fee fluctuations and
network congestion can still impact transaction processing times. Below are some
tips to ensure a smooth experience, especially when dealing with a high volume
of transaction requests.

### Higher Fees

Consider setting the `fee_level` parameter to at least MEDIUM or HIGH. This
ensures that your transactions are processed with higher priority in a
reasonable timeframe, reducing delays for subsequent transactions.

### Managing Transactions

1. **Monitor Transaction Status**: Use the list transactions API to query the
   status of your transactions.
2. **Cancellation and Acceleration**: Use the cancellation and acceleration API
   to expedite transactions that have been pending for an extended period.
3. **Transaction Notifications**: Implement transaction notifications to confirm
   the completion of transactions before sending more requests.

### Multiple Sender Wallets

Using multiple sender wallets can help bypass the per-wallet queue limit and
increase the level of parallel processing. This strategy is generally effective
across various blockchains.

### Batch Transactions with Smart Contracts

Leveraging smart contracts for batch transactions can significantly reduce the
number of transactions needed for repetitive tasks. For instance, instead of
sending 1,000,000 transfer transactions individually, you can deploy an airdrop
contract that processes transfers to 500 wallets in a single execution call,
requiring only 2,000 transactions in total. Although a single contract execution
call may incur higher gas costs than a simple transfer, it is often more gas and
time-efficient for batch transactions.

For more details, please refer to our
[Airdrop template for Circle Contracts](/contracts/airdrop) .

## Summary

By understanding the transaction queue limits and exploiting the above
optimization tips, you can improve the transaction throughput of your
applications, thereby increasing their overall efficiency when interacting with
blockchain networks.