Optimistic building, unmatchable infrastructure

Access Optimism APIs through Blast and enjoy the network's robustness, decreased transaction costs and latency. Explore the capabilities of optimistic rollups technology through Blast's leading technology and performance.

Benefits of Optimism

About Optimism

Optimism is a layer 2 (L2) blockchain, built using the optimistic-rollup technology for improved scalability. It batches transactions into groups, which are later submitted to the Ethereum mainnet that records the cumulative block state.
These rollups are presumed valid, hence the term 'optimistic rollups'. However, their authenticity can be disputed and overturned within a seven-day window. This leads to asset transfer lengths of a week from Optimism to Ethereum using the official bridge.

Optimism's approach offers the benefit of significantly reduced gas fees (in $ETH) for L2 transactions and potential long-term reductions on the Ethereum blockchain. As Ethereum will need to process fewer transaction details, a key goal for Optimism is to minimize congestion on the Ethereum mainnet. Thus, one of the main advantages is that Ethereum smart contract developers don't need to learn new programming languages or frameworks for OVM development. Optimism utilizes familiar programming languages from the Ethereum ecosystem, like Solidity and Vyper, along with toolchains such as Ethers and Hardhat.

Start building for free on Optimism with Blast APIs!

Optimism Mainnet

The main blockchain network within the Optimism ecosystem is the OP Mainnet, an EVM equivalent Layer 2 blockchain connected to Ethereum. The OP token runs at the core of the OP Mainnet and is used for paying transaction fees along with ETH. Developers can get access to Optimism public APIs for free with Blast!

Public RPC Endpoint

Public WSS Endpoint





Returns the number of the most recent block

eth_blockNumber response

Returns the number of the most recent block


An integer value of the current block number the client is on


curl -X POST https://optimism-mainnet.public.blastapi.io \
-H 'Content-Type: application/json' \
-d '{"jsonrpc":"2.0","id":0,"method":"eth_blockNumber"}'
See all Public APIs

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Blast Features for Optimism Builders

Pay on chain

With the Blast Multichain Payment solution, you can get instant access to premium RPC endpoints and pay using your non-custodial wallet directly on the Optimism mainnet!

Included with all plans

Debug & Trace APIs

The Debug API gives OP developers access to several non-standard RPC methods, which will allow them to inspect, debug and set certain debugging flags during runtime. The Trace API provides detailed information about specific transactions on OP Mainnet, including their origins, destinations, intermediate steps, and associated data. Trace & Debug APIs are enabled starting with the Developer plan.

Included with Developer, Startup, Enterprise & Pay As You Go plans

Builder API

The Builder APIs are a suite of powerful API endpoints providing access to more comprehensive and better structured blockchain data on the Optimism blockchain. You can start using the Builder APIs with the Free plan.

Included with all plans

Archive Nodes

These nodes retain all historical transaction information on the Optimism blockchain from the genesis block to the present, enabling users to query and retrieve any past information. The Archive Nodes feature is enabled starting with the Developer plan.

Included with Developer, Startup, Enterprise & Pay As You Go plans

Frequently Asked Questions

What are optimistic-rollups?

Rollups are an Ethereum scaling solution, which process transactions off-chain, using a sidechain that is connected to the main blockchain.

What is EVM-compatibility?

EVM-compatible chains are Blockchain networks that conform to the same standards and protocols as the Ethereum blockchain.

Can I use Blast to add an Optimism API in MetaMask?

Yes, you can add both a public or a dedicated API for OP by simply clicking “Add to Metamask“ on the chain page.

How can I use Blast to upload my project on Optimism?

You can use Blast to connect to Optimism by simply copy-pasting a line of code. Start for free and scale your subscription according to the resources you need.

Where do I get support if my Blast APIs are not working on Optimism?

The Bware Labs team is available 24/7 via Discord for support! Just join our server and write down your questions in the Technical Support channel.

Blast Resources for Optimism Developers

Getting started with developing on Optimism by using Blast APIs is straightforward. You can follow the instructions in our documentation to set up your development environment and start building.