# @alchemy/common > Overview of common > For the complete documentation index, see [llms.txt](/docs/llms.txt). {/* This file is auto-generated by TypeDoc. Do not edit manually. */} **Beta** — This is a low-level package that is consumed by other Alchemy packages. ## Installation ```bash npm install @alchemy/common viem ``` ## Key Exports - **`alchemyTransport`** - viem-compatible HTTP transport for Alchemy APIs (supports API key, JWT, or direct URL auth) - **Chain registry** - `getAlchemyRpcUrl`, `isChainSupported`, `getSupportedChainIds` - **Custom chain definitions** (via `@alchemy/common/chains`) - chains not yet in viem - **`AlchemyRestClient`** - typed REST client for non-JSON-RPC Alchemy APIs - **Error classes** - `BaseError`, `ChainNotFoundError`, `AccountNotFoundError`, `ConnectionConfigError`, etc. - **Logging** - `createLogger`, `setGlobalLoggerConfig`, `LogLevel` - **Utilities** - `bigIntMultiply`, `bigIntMax`, `lowerAddress`, `assertNever` ## Usage ```ts import { alchemyTransport } from "@alchemy/common"; import { sepolia } from "viem/chains"; import { createPublicClient } from "viem"; const client = createPublicClient({ chain: sepolia, transport: alchemyTransport({ apiKey: "YOUR_API_KEY" }), }); ``` ## License MIT ## Classes | Class | Description | | :--------------------------------------------------------------------------------- | :----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | [AccountNotFoundError](/wallets/reference/common/classes/AccountNotFoundError) | This error is thrown when an account could not be found to execute a specific action. It extends the `BaseError` class. | | [BaseError](/wallets/reference/common/classes/BaseError) | A custom error class that extends from `ViemBaseError`. This class allows for error messages to include links to relevant documentation based on provided `docsPath` and `docsSlug` parameters. This is based on on viem's BaseError type (obviously from the import and extend) we want the errors here to point to our docs if we supply a docsPath though | | [ChainNotFoundError](/wallets/reference/common/classes/ChainNotFoundError) | Error class representing a "Chain Not Found" error, typically thrown when no chain is supplied to the client. | | [ConnectionConfigError](/wallets/reference/common/classes/ConnectionConfigError) | Error class for connection configuration validation failures. | | [FetchError](/wallets/reference/common/classes/FetchError) | Error class representing a "Fetch Error" error, typically thrown when a fetch request fails. | | [InvalidRequestError](/wallets/reference/common/classes/InvalidRequestError) | This error is thrown when an invalid request is made. It extends the `BaseError` class. | | [MethodUnsupportedError](/wallets/reference/common/classes/MethodUnsupportedError) | This error is thrown when an unknown method is called. It extends the `BaseError` class. | | [ServerError](/wallets/reference/common/classes/ServerError) | Error class representing a "Server Error" error, typically thrown when a server request fails. | ## Interfaces | Interface | Description | | :------------------------------------------------------------------------------------ | :-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | [AlchemyTransportConfig](/wallets/reference/common/interfaces/AlchemyTransportConfig) | Configuration options for the Alchemy transport. Extends viem's HttpTransportConfig with Alchemy-specific options while omitting options that are not relevant or supported by Alchemy. | ## Type Aliases | Type Alias | Description | | :---------------------------------------------------------------------------------------- | :------------------------------------------------------------------------------------------------------------------------------------------------ | | [AlchemyConnectionConfig](/wallets/reference/common/type-aliases/AlchemyConnectionConfig) | TypeScript type derived from the schema for external consumption. This provides clean type inference without exposing Zod implementation details. | | [AlchemyTransport](/wallets/reference/common/type-aliases/AlchemyTransport) | - | | [ExtractRpcMethod](/wallets/reference/common/type-aliases/ExtractRpcMethod) | - | | [Never](/wallets/reference/common/type-aliases/Never) | - | ## Variables | Variable | Description | | :------------------------------------------------------------------------------------------------- | :------------------------------------------------------------------------------------------------------------ | | [AlchemyConnectionConfigSchema](/wallets/reference/common/variables/AlchemyConnectionConfigSchema) | Main connection configuration allowing flexible combinations. Can specify URL, auth method, or both together. | ## Functions | Function | Description | | :----------------------------------------------------------------------------------------------------- | :------------------------------------------------------------------------------------------------------------------------------------------------------- | | [alchemyTransport](/wallets/reference/common/functions/alchemyTransport) | Creates an Alchemy HTTP transport for connecting to Alchemy's services. | | [assertNever](/wallets/reference/common/functions/assertNever) | Asserts that a value is never. | | [bigIntMax](/wallets/reference/common/functions/bigIntMax) | Returns the max bigint in a list of bigints | | [bigIntMultiply](/wallets/reference/common/functions/bigIntMultiply) | Given a bigint and a number (which can be a float), returns the bigint value. Note: this function has loss and will round down to the nearest integer. | | [getAlchemyRpcUrl](/wallets/reference/common/functions/getAlchemyRpcUrl) | Gets the Alchemy RPC base URL for a given chain ID. | | [getSupportedChainIds](/wallets/reference/common/functions/getSupportedChainIds) | Gets all supported chain IDs from the registry. | | [isAlchemyConnectionConfig](/wallets/reference/common/functions/isAlchemyConnectionConfig) | Type guard to check if a value is a valid Alchemy connection config. | | [isAlchemyTransport](/wallets/reference/common/functions/isAlchemyTransport) | A type guard for the transport to determine if it is an Alchemy transport. Used in cases where we would like to do switching depending on the transport. | | [isChainSupported](/wallets/reference/common/functions/isChainSupported) | Checks if a chain ID is supported by the Alchemy RPC registry. | | [lowerAddress](/wallets/reference/common/functions/lowerAddress) | Lowercase an address | | [raise](/wallets/reference/common/functions/raise) | Raises an error. | | [validateAlchemyConnectionConfig](/wallets/reference/common/functions/validateAlchemyConnectionConfig) | Validates an Alchemy connection configuration object. |