Flashblocks on Optimism now available via Chainstack RPC

Chainstack now supports Flashblocks on Optimism, giving developers access to near real-time transaction preconfirmations through dedicated low-latency Optimism RPC endpoints.

Traditionally, applications on Optimism wait around two seconds for block confirmation. With Flashblocks, transaction updates can arrive in as little as 250 milliseconds, significantly improving responsiveness for latency-sensitive use cases such as trading platforms, prediction markets, wallets, gaming, and real-time consumer applications.

Built for the OP Stack ecosystem, Flashblocks stream transaction ordering updates before the full block is finalized. This enables developers to build applications that feel more interactive while reducing perceived confirmation delays for end users.

With Chainstack Flashblocks RPC, developers get:

• sub-second transaction feedback
• Ethereum-compatible RPC endpoints
• support for pending state reads
• minimal integration changes for existing applications
• production-grade Optimism infrastructure with global performance optimization

Flashblocks are powered by Rollup-Boost, an open-source initiative developed by Flashbots in collaboration with OP Labs and ecosystem contributors to reduce latency across OP Stack chains.

While Flashblocks were first introduced on Base, the Optimism implementation includes important OP Stack-specific architectural differences. Depending on the chain configuration, sequencing behavior and rollout mechanics may vary between networks.

If you’re new to the technology, read our guide to Flashblocks to understand how sub-block streaming and preconfirmations work across OP Stack ecosystems.

For a deeper technical comparison between Base and Optimism implementations, see the Flashblocks comparison section in the documentation.