# What is a test network?
As you know, Circle APIs represent value in the form of USDC, BTC, and ETH. [USDC](🔗) is a token running on multiple blockchains including the [Ethereum blockchain](🔗), the [Algorand blockchain](🔗), the [Solana blockchain](🔗), [Stellar blockchain](🔗), and [Hedera Hashgraph](🔗).
These blockchains also exist on various testing networks ("testnet"), allowing developers to test their applications before deploying code on the main network ("mainnet").
As the below networks are for testing only, the USDC tokens in circulation on these networks are minted in a completely arbitrary way, and **are in no way backed by real US dollars**.
Similarly, BTC and ETH on testnet and Goerli also have no intrinsic value.
# USDC on Ethereum Goerli
**Goerli** is one of the Ethereum testing networks.
The USDC smart contract has been deployed to the Goerli testnet and is available at address [0x07865c6e87b9f70255377e024ace6630c1eaa37f](🔗).
The USDC smart contract is also available on the Ropsten testnet, however Circle sandbox does not support Ropsten. On September 21st, 2021 at 8am, Circle moved the sandbox environment from Ropsten to Goerli. No historical transaction data was removed, however deposit addresses were reset. You can read more about the migration [here](🔗)
# USDC on Algorand TestNet
**TestNet** is the Algorand testing network.
The USDC Algorand Standard Asset (ASA) has been deployed to the TestNet and with asset ID [10458941](🔗).
# USDC on Solana Testnet
**Devnet** is the Solana testing network.
The USDC Solana SPL token has been deployed to the Devnet and is available on address [4zMMC9srt5Ri5X14GAgXhaHii3GnPAEERYPJgZJDncDU](🔗).
# USDC on Stellar Testnet
**Testnet** is the Stellar testing network.
The USDC Stellar asset has been deployed to the Testnet and is available at address [GBBD47IF6LWK7P7MDEVSCWR7DPUWV3NY3DTQEVFL4NAT4AQH3ZLLFLA5](🔗). Information on the asset is published at [centre.io](🔗).
# USDC on TRON Testnet
**Shasta** is the TRON testing network.
The USDC TRON token has been deployed to the Testnet and is available at address [TFGBSrddCjLJAwuryZ9DUxtEmKv13BPjnh](🔗)
# USDC on Hedera Testnet
**Testnet** is the Hedera testing network.
The USDC Hedera token has been deployed to the Testnet and is available at address [0.0.3120049](🔗)
# USDC on Avalanche Testnet
**Testnet** is the Avalanche testing network.
The USDC Avalanche token has been deployed to the Testnet and is available at address [USDC-on-AVAX token address: 0x5425890298aed601595a70ab815c96711a31bc65](🔗)
# USDC on Flow Testnet
**Testnet** is the Flow testing network.
The USDC Flow token has been deployed to the Testnet and is available at address [USDC-on-FLOW token address: A.a983fecbed621163.FiatToken](🔗)
# Bridged USDC on Polygon Testnet
Mumbai Testnet is the Polygon testing network. Polygon USDC is a bridged version of USDC that has been bridged from Ethereum to the Polygon PoS network via the Polygon PoS Bridge.
Polygon USDC is available at address [0x0fa8781a83e46826621b3bc094ea2a0212e71b23](🔗)
# Testnets and Circle APIs on Sandbox
Circle's [sandbox environment](🔗) is connected to USDC on the testing networks listed above.
In other words, when you send funds from a Circle hosted wallet to an external blockchain address, it will be sent as USDC on the testnet. Similarly, if you want to receive funds from an external blockchain address, you can use USDC on the testnet to achieve that.
For BTC and ETH support in Sandbox, we use **testnet** and **Goerli**, respectively.