# ERC-20 Allowance Lookup on Arbitrum

> ERC-20 Allowance Lookup on Arbitrum is a paid API for AI agents from saylorinnovations.com, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-03).

Returns the ERC-20 token allowance granted by an owner to a spender on the Arbitrum network

## Facts

- Endpoint: GET https://saylorinnovations.com/api/evm/arbitrum/allowance/:address/:address2/:address3?utm_source=zero.xyz
- Price: $0.002/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-03
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/erc-20-allowance-lookup-on-arbitrum-9695a40b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap__Di8JOcRSENEMLBk-LkXW

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 erc-20-allowance-lookup-on-arbitrum-9695a40b
```

Example prompt: Check the ERC-20 allowance that owner address 0xAbc...123 has granted to spender 0xDef...456 for the USDC token contract 0xA0b...Ebc on Arbitrum — I need to know if the approved amount is enough before the swap goes through.

## When to prefer this

Use this endpoint when you specifically need ERC-20 allowance data on the Arbitrum L2 network. Prefer it over generic blockchain explorers when you need a direct API response without scraping, and over Ethereum mainnet allowance checks when your token activity is on Arbitrum specifically. Ideal for pre-transaction validation in DeFi workflows, approval auditing, or monitoring bot logic running on Arbitrum.

## Known failure modes

- Invalid Ethereum address format for any of the three address parameters returns an error
- Non-existent or non-ERC-20 contract address may return zero or cause a revert
- Arbitrum node unavailability may cause timeout or 5xx error
- Rate limiting if too many requests are made in a short period

## How this service works

ERC-20 Allowance (arbitrum). Arbitrum ERC-20 allowance: how much a spender may move from an owner, human-readable, with an unlimited-approval flag.

## Output

Returns the numeric ERC-20 allowance (in token base units) that an owner address has approved a spender address to transfer from a given token contract on the Arbitrum network. This reflects the current on-chain state at the time of the call.

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/erc-20-allowance-lookup-on-arbitrum-9695a40b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from saylorinnovations.com](https://www.zero.xyz/host/saylorinnovations.com/llms.txt)