Indexing Data on Base Sepolia Testnet

Base Sepolia Testnet is the primary public test network for Base, Coinbase’s OP Stack Ethereum Layer 2, where teams deploy and validate contracts before mainnet. The Graph can stream that onchain activity — DEX swaps, pools, and liquidity; lending and borrowing positions; token transfers and holder balances; and contract events — as real-time data with Substreams.

Base Sepolia Testnet is supported by The Graph with Substreams — a parallelized, real-time streaming engine for high-throughput use cases — via Pinax Network⁠.

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Substreams is a parallelized, real-time streaming engine for extracting and transforming blockchain data. Where a Subgraph indexes into a hosted GraphQL API, Substreams lets you consume high-throughput data directly or via 10+ supported sinks. Base Sepolia Testnet is served with the extended EVM block model, so Substreams modules have access to full transaction, call, and event data. Modules are written in Rust and composed into reusable packages.

Find an Existing Module on Substreams.dev

Before writing any code, check the Substreams Registry⁠ for a package that already does what you need. The registry hosts community- and team-built modules — DEX trades, token transfers, contract events, and more — that you can run as-is or compose into your own pipeline. Search for the protocol or data you want on Base Sepolia Testnet; if a module fits, you can consume its output directly or import it as a dependency in your own project.

Develop Your Own Substreams Module

If no existing module fits, you can build one. The Substreams Quick Start is the full walkthrough. In short:

1. Install the Substreams CLI and get an API key from Pinax Network.
2. Scaffold a project with substreams init and choose the EVM path, pointing it at your Base Sepolia Testnet contract.
3. Write your extraction and transformation logic in Rust, then run substreams build.
4. Stream the output with substreams gui (or substreams run) to iterate, then publish your package to the Substreams Registry⁠ to reuse or share it.