RPC Passthrough

Send any JSON-RPC method call directly to a BuildBear sandbox and print the result. Useful for debugging, inspecting chain state, or invoking BuildBear-specific RPC extensions without writing custom scripts.

buildbear rpc [rpcUrl] --method <method> [--params <json>] [options]

Arguments:

Options:

[!NOTE] buildbear rpc always outputs JSON — the --json flag is implicit and cannot be disabled.

Examples

Get the current block number:

buildbear rpc --method eth_blockNumber

{
  "method": "eth_blockNumber",
  "result": "0x140A2E0"
}

Get the balance of an address:

buildbear rpc --method eth_getBalance \
  --params '["0xYourWalletAddress", "latest"]'

{
  "method": "eth_getBalance",
  "result": "0x8AC7230489E80000"
}

Call a contract function (raw eth_call):

buildbear rpc --method eth_call \
  --params '[{"to": "0xContractAddress", "data": "0x06fdde03"}, "latest"]'

Read params from a file:

cat params.json
["0xYourWalletAddress", "latest"]

buildbear rpc --method eth_getBalance --params @params.json

Use an explicit RPC URL:

buildbear rpc https://rpc.buildbear.io/my-sandbox-id \
  --method eth_chainId

Common JSON-RPC methods

BuildBear-specific RPC methods

BuildBear sandboxes extend the standard JSON-RPC API with custom methods:

The buildbear faucet and buildbear snapshot commands are wrappers around these methods. Use buildbear rpc when you need direct access or when building custom tooling.

Output format

The output is always a JSON object with two keys:

{
  "method": "<the method you called>",
  "result": "<the raw JSON-RPC result>"
}