Optimism Sepolia RPC Endpoints & API | OnFinality

Optimism’s Sepolia Testnet

Connect to Optimism Sepolia in seconds with OnFinality RPC endpoints, request analytics, scalable rate limits, and 99.99% uptime for production Web3 apps.

Optimism’s Sepolia Testnet

Create RPC Endpoint

Optimism Sepolia RPC Endpoint

The below example uses the public API endpoint*. This endpoint is only suitable for testing. To avoid rate limiting and service interruption, sign up now to get your own API key.

* The public endpoint is rate limited

RPC API Service

RPC API Features

ArchiveTrace

Optimism Sepolia RPC Endpoints

Optimism Sepolia is the official testnet for Optimism, an Ethereum Layer 2 scaling solution using optimistic rollups. It mirrors the OP Mainnet environment, allowing developers to deploy and test dApps, wallets, DeFi protocols, and smart contracts before going to production. The network uses the OP Stack and is part of the Superchain ecosystem.

Why Use Optimism Sepolia RPC?

To interact with Optimism Sepolia, applications need an RPC endpoint. This endpoint serves as the gateway for reading blockchain data, submitting transactions, and connecting backend services. Whether you are building a DeFi dApp, a wallet, an analytics tool, or a bot, a reliable RPC connection is essential.

OnFinality Optimism Sepolia RPC

OnFinality provides managed RPC API endpoints for Optimism Sepolia. With OnFinality, you can:

Access authenticated endpoints with clearer usage limits and request analytics.
Scale from shared APIs to higher-capacity plans as your project grows.
Use archive and trace capabilities where supported, enabling deep historical data queries and debugging.
Monitor request usage, errors, and limits through the OnFinality dashboard.

Key Facts

Network environment: testnet
RPC protocol: EVM JSON-RPC
Transport: HTTP and WebSocket
Advanced access: archive, trace (availability depends on plan)
Common use cases: production dApps, wallets, DeFi products, analytics tools, games, bots, and backend services

How to Connect

Create or sign in to your OnFinality account.
Select Optimism Sepolia from the supported networks list.
Create an API endpoint or deploy a dedicated node (if supported).
Test the endpoint using eth_blockNumber.
Monitor usage before moving critical traffic.

Public vs Private RPC

Public RPC endpoints are suitable for lightweight testing but often have rate limits and no observability. OnFinality endpoints provide authenticated access, request analytics, and a path to higher capacity, making them ideal for team projects and production workloads.

Conclusion

Optimism Sepolia is a critical testnet for Ethereum Layer 2 development. With OnFinality, you get reliable, scalable RPC infrastructure to build and test your applications with confidence.