Flashblocks API Quickstart

Get started building on Optimism using Flashblocks

Introduction

Flashblocks on Optimism are a transaction preconfirmation feature that provides near-instant transaction feedback by streaming partial block updates every 200 milliseconds. This significantly reduces the effective block time from Optimism’s standard 2 seconds to just 200 milliseconds, a 10x increase.

Flashblocks is great for developers who demand instant UX such as decentralized exchanges, onchain gaming, and other high-frequency applications.

Getting started instructions

Flashblocks is currently supported on both Optimism Sepolia testnet and mainnet and can be accessed using your existing Alchemy Optimism RPC.

NetworkFlashblocks Availability
Optimism Sepolia
Optimism MainnetTBA

Flashblocks-enabled API Endpoints