# Delx EVM Calldata Size Bytes

> Delx EVM Calldata Size Bytes is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-13).

Computes the byte length of EVM calldata hex strings for preflight validation before on-chain submission.

## Facts

- Endpoint: POST https://api.delx.ai/api/v1/x402/evm-calldata-size-bytes
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-13
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/delx-evm-calldata-size-bytes-db400bc0
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_w0cd9ppiWzGtJwDnFC0by

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability delx-evm-calldata-size-bytes-db400bc0 -d '<json body>'
```

Example prompt: How many bytes is this EVM calldata: 0x1234abcd? I want to check if it's valid before I submit the transaction.

## When to prefer this

Use this endpoint when you need a fast, verifiable, privacy-preserving byte-size check on EVM calldata before submitting or estimating gas for a transaction. It's ideal for agent preflight pipelines where you need an auditable SHA256 receipt confirming no data was retained. Prefer it over manual hex parsing when you want a structured validity flag alongside the count.

## Known failure modes

- Malformed hex string (not 0x-prefixed or invalid hex characters) may return shape_valid: false
- Input exceeding 8192 character maxLength will be rejected
- Empty calldata string may return a zero byte count or validation error
- Non-string calldata input will fail schema validation

## How this service works

EVM Calldata Size Bytes: EVM Calldata Size Bytes calculates calldata byte length from normalized hex from bounded caller-supplied values without an external provider. Call EVM Calldata Size Bytes before signing, submitting, replacing, or accepting an EVM/Base transaction assembled from caller-owned data. Returns normalized transaction evidence, calculated budget or shape findings, and a fail-closed preflight status for EVM Calldata Size Bytes as versioned deterministic JSON. Price: $0.001 USDC…

## Output

Returns a JSON object containing the original calldata string, its byte_count as an integer, a shape_valid boolean indicating whether the calldata is well-formed, the operation name, status ('pass'), and evidence metadata including whether input was retained (always false), the SHA256 hash of the input, and the number of external calls made (always 0).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "calldata": {
   "type": "string",
   "maxLength": 8192,
   "description": "Calldata supplied to EVM Calldata Size Bytes; used only for this bounded calculation and processed in memory without retention."
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "result": {
   "calldata": "0x1234abcd",
   "byte_count": 4,
   "shape_valid": true
  },
  "schema": "delx/util-evm-calldata-size-bytes/v1",
  "status": "pass",
  "evidence": {
   "retained": false,
   "input_sha256": "6ffdb637cbb0ee3342cdd21ba540914ee72f80a467cba5a39651837c42e42662",
   "external_calls": 0
  },
  "operation": "evm_preflight:evm_calldata_size_bytes"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/delx-evm-calldata-size-bytes-db400bc0/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.delx.ai](https://www.zero.xyz/host/api.delx.ai/llms.txt)