# Optimism API

The Crypto APIs Optimism API, part of the Blockchain API, lets you read balances, token transfers and blocks on Optimism and send transactions without running a node. One API key covers mainnet and sepolia. Webhooks tell your server when a payment confirms, and we never hold your private keys.

## Key facts

| | |
| --- | --- |
| Networks | Mainnet, Sepolia |
| Model | Account (EVM) |
| Endpoints | 34 |
| Confirmations webhook | Yes, per address |
| Custody | Non-custodial, you sign |
| Free trial | 14 days, no card |

## How do I get the latest Optimism block?

Send one GET request with your API key; the same request works on sepolia when you replace mainnet with sepolia in the path.

```
curl https://rest.cryptoapis.io/blocks/evm/optimism/mainnet/latest/details \
  -H "X-API-Key: YOUR_API_KEY"
```

## Which Optimism endpoints are available?

The main calls. Every path takes the network: mainnet or sepolia.

| What it does | Method and path | Reference |
| --- | --- | --- |
| Latest block | `GET /blocks/evm/optimism/mainnet/latest/details` | [Docs](https://developers.cryptoapis.io/v-2.2024-12-12-175/RESTapis/blocks-evm/get-last-mined-block-evm/get) |
| Block by height | `GET /blocks/evm/optimism/mainnet/height/{blockHeight}/details` | [Docs](https://developers.cryptoapis.io/v-2.2024-12-12-175/RESTapis/blocks-evm/get-block-details-by-block-height-evm/get) |
| Address balance | `GET /addresses-latest/evm/optimism/mainnet/{address}/balance` | [Docs](https://developers.cryptoapis.io/v-2.2024-12-12-175/RESTapis/address-latest-evm/get-address-balance-evm/get) |
| Transactions of an address | `GET /addresses-latest/evm/optimism/mainnet/{address}/transactions` | [Docs](https://developers.cryptoapis.io/v-2.2024-12-12-175/RESTapis/address-latest-evm/list-confirmed-transactions-by-address-evm/get) |
| Token transfers of an address | `GET /addresses-latest/evm/optimism/mainnet/{address}/tokens-transfers` | [Docs](https://developers.cryptoapis.io/v-2.2024-12-12-175/RESTapis/address-latest-evm/list-confirmed-tokens-transfers-by-address-evm/get) |
| Transaction by hash | `GET /transactions/evm/optimism/mainnet/{transactionHash}` | [Docs](https://developers.cryptoapis.io/v-2.2024-12-12-175/RESTapis/transactions-data-evm/get-transaction-details-by-transaction-hash-evm/get) |
| Fee recommendations | `GET /blockchain-fees/evm/optimism/mainnet/mempool` | [Docs](https://developers.cryptoapis.io/v-2.2024-12-12-175/RESTapis/blockchain-fees-evm/get-fee-recommendations-evm/get) |
| Prepare an unsigned transaction | `POST /prepare-transactions/evm/optimism/mainnet/native-coins` | [Docs](https://developers.cryptoapis.io/v-2.2024-12-12-175/RESTapis/prepare-transactions-evms/prepare-transaction-from-address-evm/post) |
| Broadcast a signed transaction | `POST /broadcast-transactions/optimism/mainnet` | [Docs](https://developers.cryptoapis.io/v-2.2024-12-12-175/RESTapis/broadcast-locally-sign-transactions/broadcast-locally-signed-transaction/post) |
| Webhook on a confirmed payment | `POST /blockchain-events/optimism/mainnet/address-coins-transactions-confirmed` | [Docs](https://developers.cryptoapis.io/v-2.2024-12-12-175/RESTapis/create-subscriptions-for/new-confirmed-coins-transactions/post) |

## Optimism API questions

**Is there a free Optimism API?** You can try it free for 14 days. The Blockchain API free trial covers Optimism and every feature, with no card. It ends after 14 days or when its credits run out; after that, calls need a subscription, listed on the pricing page.

**How do I get the balance of a Optimism address?** Call the address balance endpoint with the address; it returns the confirmed ETH balance. Token balances live in the token contracts, so list the address's token transfers to see them.

**How do I broadcast a Optimism transaction?** Sign the transaction on your own server, then send the signed raw transaction to the broadcast endpoint, authenticated with your API key, and Crypto APIs pushes it to the Optimism network and returns the transaction ID. We can prepare the unsigned transaction for you first.

**Do you support Optimism sepolia?** Yes. Every Optimism endpoint works on mainnet and sepolia. Change mainnet to sepolia in the path; the same API key works on both.

**What makes Optimism different to work with?** It is an account-model EVM chain — every address has a single balance and a nonce. Tokens live in their own contracts rather than in the account balance, so reading them means calling the token contract; and every transaction needs the account's next nonce, which the same API returns.

**How do I know when a Optimism transaction is confirmed?** Create a webhook subscription for the address. Crypto APIs calls your URL when a transaction to or from it confirms on Optimism.

## The Optimism Blockchain

Optimism is a Layer-2 scaling solution for Ethereum, aiming to improve transaction throughput and reduce fees by employing optimistic rollups, a technology that enables faster and more cost-effective smart contract execution.

Optimism blockchain, crafted by Ethereum developers for Ethereum developers, stands as a swift, reliable, and scalable Layer 2 blockchain. Functioning as a streamlined augmentation to current Ethereum software, Optimism architecture mirrors the EVM, ensuring seamless scalability for your Ethereum applications. If a feature operates on Ethereum, it seamlessly translates to OP Mainnet, offering the same functionality at a significantly reduced cost.

| About Optimism | |
| --- | --- |
| Released | 2019 |
| Consensus | Optimistic Rollups |
| Block time | 2 seconds |
| Smart contracts | Yes |

## Other EVM chains, same request shape

- [Arbitrum API](/chains/arbitrum-one)
- [Base API](/chains/base)
- [Ethereum API](/chains/ethereum)

## Pointers

- [Blockchain API](/products/blockchain-api)
- [All networks](/what-we-support)
- [Pricing](/pricing)
- [Developer portal](https://developers.cryptoapis.io/)