The Squid SDK is a set of tools to ingest, transform and present blockchain data.

The SDK currently supports indexing of EVM- and Substrate-based chains.

The best way to get started is to install squid CLI and scaffold a squid project with sqd init.

For step-by-step instructions, follow one of the Quickstart guides.

The Squid SDK consists of several key components.

substrate-processor (for Substrate-based networks) and evm-processor(for EVM networks) fetch on-chain data from an Archive and execute user-defined data mapping code to transform and persist the data into the target database.

squid-substrate-typegen(1) generates facade TypeScript classes for type-safe decoding substrate events, calls and RPC storage queries. It natively supports Substrate runtime upgrades by inspecting the historical metadata changes and generating runtime version-aware data access methods.

Similarly, squid-evm-typegen(1) generates facade TypeScript classes for type-safe decoding of EVM event logs, transaction data and RPC contract state responses.

Both evm-processor and substrate-processor are designed to be able to load the processed data into an arbitrary database and indeed one can run it without a persistent store.

Extra tooling for data modeling and serving the data with GraphQL is available when a processor is run against a postgres-compatible database. In such a case, the Subsquid framework suggests the following dev flow:

1. Define the target database schema using a GraphQL dialect enriched with custom directives
2. Generate TypeORM entity classes with typeorm-codegen
3. Generate and apply database migrations with typeorm-migration
4. Use powerful and extensible GraphQL server to serve the produced data.

See the docs for more details on the data modelling using the schema file and an auto-generated GraphQL API over it.

The Subsquid framework incorporates a few npm packages that might be useful in a standalone mode:

• commands - a cross-platform runner of project-specific commands. Designed to replace Makefile and package.json scripts for squid projects. Natively integrated in squid CLI.
• scale-codec - encoder and decoder for SCALE data serialization format
• ss58-codec - encoder and decoder for SS58 address format
• ss58 - ss58-codec paired with SS58 registry.

An Archive is a specialized data lake optimized for batch access to the historical event and transaction data. Archives are the primary data sources for squid projects developed with the Squid SDK. Currently, public Archives are maintained by the Subsquid Labs GmbH and will be replaced by a decentralized solution in the future.

• For EVM chains, see a separate eth-archive repo. For a list of public EVM archive endpoints, see the docs.

• For Substrate chains, the archive service is formed by substrate-ingest, substrate-gateway, postgres compatible database and optionally substrate-explorer, which together

1. ingest blockchain data
2. decode and persist it in a normalized form
3. make it available for further processing and exploration.

For a list of public Substrate archives, see the Aquarium page.

Compared to data access using a conventional chain node RPC, an archive allows one to access data in a more granular fashion and from multiple blocks at once.

Our developers are active on Telegram and Discord. Feel free to join and ask any question!

Subsquid is an OpenSource project, contributions are welcomed, encouraged and will be rewarded!

Please consult CONTRIBUTING.md for hacking instructions and make sure to read our code of conduct.