# Vextorium EVM/Solana Function Selector Decoder

> Vextorium EVM/Solana Function Selector Decoder is a paid API for AI agents from api.vextorium.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-15).

Decodes an EVM function selector (4 bytes) or event topic hash (32 bytes) into human-readable Solana/EVM ABI signatures using the 4byte.directory database

## Facts

- Endpoint: POST https://api.vextorium.com/v1/decode-selector?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/vextorium-evm-solana-function-selector-decoder-f2a6ab16
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_eDqYJPBErOf8Ro9xt9-4n

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 vextorium-evm-solana-function-selector-decoder-f2a6ab16 -d '<json body>'
```

Example prompt: What function does the EVM selector 0xa9059cbb correspond to? Decode it for me and show all possible matching ABI signatures.

## When to prefer this

Use this endpoint when you need to reverse-engineer an EVM function selector (4 bytes, 0x + 8 hex) or event topic hash (32 bytes, 0x + 64 hex) into a human-readable ABI signature. Ideal for transaction analysis, calldata decoding, smart contract auditing, and DeFi debugging. Prefer this over manual 4byte.directory lookups when automating on-chain data pipelines.

## Known failure modes

- Selector not found in 4byte.directory — returns empty signatures array
- Invalid hex format (missing 0x prefix or wrong byte length) — validation error
- Selector has multiple collisions — returns all candidates with a note that the oldest is usually correct
- Network timeout to upstream 4byte.directory — may return error

## How this service works

558 pay-per-call data APIs for AI agents: Solana and EVM on-chain data, tokenized stocks, DeFi, Hyperliquid, economy and official statistics, FX, validation, web and developer tools. Pay in USDC via x402.

## Output

Returns the decoded function or event signature(s) matching the provided selector or topic hash, including the hex code, type (function or event), source database (4byte.directory), number of possible colliding signatures, and a note about collisions. The oldest/most common match is typically the canonical one.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "signature": {
   "type": "string",
   "description": "Function selector (0x + 8 hex) or event topic (0x + 64 hex)"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "code": "0xa9059cbb",
  "note": "The same code can match several signatures (collisions); the oldest is usually the real one. Source: 4byte.directory.",
  "type": "funcion",
  "source": "4byte.directory",
  "possible": 6,
  "signatures": [
   "transfer(address,uint256)",
   "many_msg_babbage(bytes1)"
  ]
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/vextorium-evm-solana-function-selector-decoder-f2a6ab16/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.vextorium.com](https://www.zero.xyz/host/api.vextorium.com/llms.txt)