# Simulate EVM transactions

Simulate one or more EVM transactions and return execution results.

Endpoint: POST /simulate/evm/{chain_gid}
Version: 0.27.5
Security: Auth

## Path parameters:

  - `chain_gid` (string, required)
    Blockchain identifier in CAIP-2 format (namespace:reference).

## Request fields (application/json):

  - `validation` (boolean)
    When true, the simulation checks sender balance, nonce sequence, and
fee consistency the same way a real submission would. When false
(default), missing parameters are filled with permissive defaults
and balance is not checked.

  - `block_state_calls` (array, required)
    Blocks to simulate.

  - `block_state_calls.calls` (array, required)
    Calls in this block.

  - `block_state_calls.calls.from` (string, required)
    Sender address.
    Example: 0x974caa59e49682cda0ad2bbe82983419a2ecc400

  - `block_state_calls.calls.to` (string, required)
    Recipient address.
    Example: 0xd0930a8fc56fd94038250bb93dbac0e13da4eb99

  - `block_state_calls.calls.value` (string)
    Transfer value in wei (decimal or 0x hex).
    Example: 10000000000000000

  - `block_state_calls.calls.data` (string)
    Call data (hex).
    Example: 0xa9059cbb000000000000000000000000d0930a8fc56fd94038250bb93dbac0e13da4eb99000000000000000000000000000000000000000000000000000000003b9aca00

  - `block_state_calls.calls.nonce` (string)
    Sender nonce (decimal or 0x hex). If omitted, the current nonce is used.
    Example: 1

  - `block_state_calls.calls.gas` (string)
    Gas limit (decimal or 0x hex). If omitted, no limit is enforced.
    Example: 21000

  - `block_state_calls.calls.gas_price` (string)
    Gas price in wei (decimal or 0x hex). Legacy transactions only. Mutually exclusive with max_fee_per_gas / max_priority_fee_per_gas.
    Example: 1000000000

  - `block_state_calls.calls.max_fee_per_gas` (string)
    Max fee per gas in wei (decimal or 0x hex). EIP-1559 only. Mutually exclusive with gas_price.
    Example: 2000000000

  - `block_state_calls.calls.max_priority_fee_per_gas` (string)
    Priority fee (tip) per gas in wei (decimal or 0x hex). EIP-1559 only. Mutually exclusive with gas_price.
    Example: 1000000000

## Response 200 fields (application/json):

  - `items` (array, required)
    List of simulated transaction results, one per input call in submission order.

  - `items.chain_gid` (string, required)
    Blockchain identifier in [CAIP-2](https://chainagnostic.org/CAIPs/caip-2) format.
Format: `{namespace}:{reference}`
- **namespace**: Ecosystem identifier (3-8 chars, lowercase)
- **reference**: Blockchain identifier within namespace (1-32 chars)

**Examples**:
- `eip155:1` — Ethereum mainnet
- `eip155:56` — BNB Smart Chain mainnet
- `eip155:137` — Polygon mainnet
- `bip122:000000000019d6689c085ae165831e93` — Bitcoin mainnet
- `tron:mainnet` — Tron mainnet
    Example: eip155:1

  - `items.hash` (string, required)
    Transaction hash identifier on the blockchain.
    Example: 0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef

  - `items.block_number` (integer, required)
    Block number/height on the blockchain.
    Example: 18500000

  - `items.is_success` (boolean, required)
    Transaction execution status.

  - `items.confirmed_at` (any, required)
    Timestamp when the transaction reached required confirmations. Null if the transaction is not yet confirmed.

  - `items.created_at` (string, required)
    Timestamp when the resource was created.
    Example: 2024-01-15T10:30:00Z

  - `items.events` (array, required)
    Canonical events that would be emitted, ordered by sequence.

  - `items.events.sequence` (integer, required)
    Event position within the transaction (0-based).

  - `items.events.kind` (string, required)
    Type of canonical event.
    Enum: "transfer", "utxo_transfer", "fee", "approval", "call", "contract_create"

  - `items.events.data` (any, required)

  - `items.events.data.kind` (string, required)
    Enum: "transfer"

  - `items.events.data.asset_gid` (string, required)
    Global asset identifier in [CAIP-19](https://chainagnostic.org/CAIPs/caip-19) format.
Format: `{chain_gid}/{asset_path}`
**Examples**:
- `eip155:1/slip44:60` — ETH on Ethereum
- `eip155:1/erc20:0xdAC17F958D2ee523a2206206994597C13D831ec7` — USDT on Ethereum
- `eip155:56/bep20:0x55d398326f99059fF775485246999027B3197955` — USDT on BNB Smart Chain
- `tron:0x2b6653dc/trc20:TR7NHqjeKQxGTCi8q8ZY4pL8otSzgjLj6t` — USDT on Tron
- `eip155:137/erc20:0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174` — USDC on Polygon
    Example: eip155:1/erc20:0xdAC17F958D2ee523a2206206994597C13D831ec7

  - `items.events.data.from` (string, required)
    Blockchain address in its native format.
**Format by network**:
- **EVM**: `0x` + 40 hex chars (normalized to [EIP-55](https://eips.ethereum.org/EIPS/eip-55) checksum on import)
- **Bitcoin**: P2PKH (1...), P2SH (3...), P2WPKH (bc1...)
- **Solana**: Base58, 32-44 chars
- **Tron**: Base58, starts with `T`
    Example: 0x8521E8b15eCEF4D4269Fded3E6694225E096959E

  - `items.events.data.amount` (object, required)
    Asset amount in base units, plus a human-readable value when we know
the token's decimals.
    Example: {"base":"1000000000","formatted":"1.0"}

  - `items.events.data.amount.base` (string, required)
    Amount in the smallest asset unit.

  - `items.events.data.amount.formatted` (string)
    Human-readable amount.

  - `items.events.data.token_id` (string)
    Token identifier for NFTs (ERC-721/ERC-1155).

  - `items.events.data.source` (string, required)
    Source type of the transfer.
    Enum: "native", "contract", "internal"

  - `items.events.data.inputs` (array, required)
    All transaction inputs (funding sources with prevout data).

  - `items.events.data.inputs.index` (integer, required)
    Position in the transaction (vin index for inputs, vout index for outputs).

  - `items.events.data.outputs` (array, required)
    All transaction outputs (destinations).

  - `items.events.data.token_id` (string)
    Token identifier for NFT approvals (ERC-721/ERC-1155).

  - `items.activity` (array, required)
    Predicted balance changes for involved addresses.

  - `items.activity.direction` (string, required)
    Direction of the asset movement relative to the tracked address.
    Enum: "in", "out"

  - `items.activity.delta` (object, required)
    Signed balance change in base units, plus a human-readable value
when we know the token's decimals.

  - `items.activity.delta.base` (string, required)
    Signed amount in the smallest asset unit.

  - `items.activity.delta.formatted` (string)
    Human-readable signed amount.

  - `items.error` (object)
    Error details for a failed simulation.
    Example: {"code":-32000,"message":"execution reverted","data":"0x"}

  - `items.error.code` (integer, required)
    Error code from the EVM execution.
    Example: -32000

  - `items.error.message` (string, required)
    Human-readable error message.
    Example: execution reverted

  - `items.error.data` (string)
    Raw revert data (hex-encoded) for detailed error decoding.
    Example: 0x08c379a00000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000001a4e6f7420656e6f75676820746f6b656e2062616c616e636500000000000000

  - `references` (object, required)
    Related objects included in the response, keyed by ID.

## Response 400 fields (application/problem+json):

  - `type` (string, required)
    A URI that identifies the error type.
Open it in a browser to read about this category of error.
    Example: https://docs.vilna.io/apis/problems/internal-error

  - `title` (string, required)
    A short summary of the error type.
Use `detail` for information specific to this occurrence.
    Example: Bad Request

  - `status` (integer, required)
    The HTTP status code for this error.
Matches the status code of the HTTP response.
    Example: 400

  - `detail` (string)
    A human-readable explanation of what went wrong in this specific case.
May be localized.
    Example: The address is already assigned to another invoice

  - `instance` (string)
    A URI that identifies this specific error occurrence.
Include this value when contacting support.
    Example: /errors?id=XXXXXX-xxxxx

  - `code` (string, required)
    Stable machine-readable error code (`{domain}.{reason}`) for programmatic error handling. Unlike the HTTP `status` or free-form `detail`, this code is guaranteed not to change between versions for a given error condition, so it is safe to branch on in client code. Defaults to `unspecified` when the server has not assigned a specific code.
    Example: resource.not_found

  - `fields` (array)
    List of invalid fields in the request

  - `fields.name` (string, required)
    The name of the invalid field
    Example: meta

  - `fields.reason` (string, required)
    Why this field is invalid
    Example: Exceeded maximum data size — must not exceed 1000 characters

## Response 401 fields (application/problem+json):

  - `type` (string, required)
    A URI that identifies the error type.
Open it in a browser to read about this category of error.
    Example: https://docs.vilna.io/apis/problems/internal-error

  - `title` (string, required)
    A short summary of the error type.
Use `detail` for information specific to this occurrence.
    Example: Bad Request

  - `status` (integer, required)
    The HTTP status code for this error.
Matches the status code of the HTTP response.
    Example: 400

  - `detail` (string)
    A human-readable explanation of what went wrong in this specific case.
May be localized.
    Example: The address is already assigned to another invoice

  - `instance` (string)
    A URI that identifies this specific error occurrence.
Include this value when contacting support.
    Example: /errors?id=XXXXXX-xxxxx

  - `code` (string, required)
    Stable machine-readable error code (`{domain}.{reason}`) for programmatic error handling. Unlike the HTTP `status` or free-form `detail`, this code is guaranteed not to change between versions for a given error condition, so it is safe to branch on in client code. Defaults to `unspecified` when the server has not assigned a specific code.
    Example: resource.not_found

## Response 403 fields (application/problem+json):

  - `type` (string, required)
    A URI that identifies the error type.
Open it in a browser to read about this category of error.
    Example: https://docs.vilna.io/apis/problems/internal-error

  - `title` (string, required)
    A short summary of the error type.
Use `detail` for information specific to this occurrence.
    Example: Bad Request

  - `status` (integer, required)
    The HTTP status code for this error.
Matches the status code of the HTTP response.
    Example: 400

  - `detail` (string)
    A human-readable explanation of what went wrong in this specific case.
May be localized.
    Example: The address is already assigned to another invoice

  - `instance` (string)
    A URI that identifies this specific error occurrence.
Include this value when contacting support.
    Example: /errors?id=XXXXXX-xxxxx

  - `code` (string, required)
    Stable machine-readable error code (`{domain}.{reason}`) for programmatic error handling. Unlike the HTTP `status` or free-form `detail`, this code is guaranteed not to change between versions for a given error condition, so it is safe to branch on in client code. Defaults to `unspecified` when the server has not assigned a specific code.
    Example: resource.not_found

## Response 404 fields (application/problem+json):

  - `type` (string, required)
    A URI that identifies the error type.
Open it in a browser to read about this category of error.
    Example: https://docs.vilna.io/apis/problems/internal-error

  - `title` (string, required)
    A short summary of the error type.
Use `detail` for information specific to this occurrence.
    Example: Bad Request

  - `status` (integer, required)
    The HTTP status code for this error.
Matches the status code of the HTTP response.
    Example: 400

  - `detail` (string)
    A human-readable explanation of what went wrong in this specific case.
May be localized.
    Example: The address is already assigned to another invoice

  - `instance` (string)
    A URI that identifies this specific error occurrence.
Include this value when contacting support.
    Example: /errors?id=XXXXXX-xxxxx

  - `code` (string, required)
    Stable machine-readable error code (`{domain}.{reason}`) for programmatic error handling. Unlike the HTTP `status` or free-form `detail`, this code is guaranteed not to change between versions for a given error condition, so it is safe to branch on in client code. Defaults to `unspecified` when the server has not assigned a specific code.
    Example: resource.not_found

## Response 422 fields (application/problem+json):

  - `type` (string, required)
    A URI that identifies the error type.
Open it in a browser to read about this category of error.
    Example: https://docs.vilna.io/apis/problems/internal-error

  - `title` (string, required)
    A short summary of the error type.
Use `detail` for information specific to this occurrence.
    Example: Bad Request

  - `status` (integer, required)
    The HTTP status code for this error.
Matches the status code of the HTTP response.
    Example: 400

  - `detail` (string)
    A human-readable explanation of what went wrong in this specific case.
May be localized.
    Example: The address is already assigned to another invoice

  - `instance` (string)
    A URI that identifies this specific error occurrence.
Include this value when contacting support.
    Example: /errors?id=XXXXXX-xxxxx

  - `code` (string, required)
    Stable machine-readable error code (`{domain}.{reason}`) for programmatic error handling. Unlike the HTTP `status` or free-form `detail`, this code is guaranteed not to change between versions for a given error condition, so it is safe to branch on in client code. Defaults to `unspecified` when the server has not assigned a specific code.
    Example: resource.not_found

  - `fields` (array)
    List of fields that failed precondition validation

  - `fields.name` (string, required)
    The name of the field that failed validation
    Example: status

  - `fields.reason` (string, required)
    Why the precondition failed for this field
    Example: Cannot transition from archived to active state

## Response default fields (application/problem+json):

  - `type` (string, required)
    A URI that identifies the error type.
Open it in a browser to read about this category of error.
    Example: https://docs.vilna.io/apis/problems/internal-error

  - `title` (string, required)
    A short summary of the error type.
Use `detail` for information specific to this occurrence.
    Example: Bad Request

  - `status` (integer, required)
    The HTTP status code for this error.
Matches the status code of the HTTP response.
    Example: 400

  - `detail` (string)
    A human-readable explanation of what went wrong in this specific case.
May be localized.
    Example: The address is already assigned to another invoice

  - `instance` (string)
    A URI that identifies this specific error occurrence.
Include this value when contacting support.
    Example: /errors?id=XXXXXX-xxxxx

  - `code` (string, required)
    Stable machine-readable error code (`{domain}.{reason}`) for programmatic error handling. Unlike the HTTP `status` or free-form `detail`, this code is guaranteed not to change between versions for a given error condition, so it is safe to branch on in client code. Defaults to `unspecified` when the server has not assigned a specific code.
    Example: resource.not_found