# ERC-20 Token Allowance Lookup on Base (Saylor Innovations)

> ERC-20 Token Allowance Lookup on Base (Saylor Innovations) 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).

Retrieves the current ERC-20 token spending allowance granted by a token owner to a spender on the Base blockchain

## Facts

- Endpoint: GET https://saylorinnovations.com/api/evm/base/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-token-allowance-lookup-on-base-saylor-innovations-a228aa7f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_QlqXUsFe54qJymYAGYlyz

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-token-allowance-lookup-on-base-saylor-innovations-a228aa7f
```

Example prompt: What is the current ERC-20 token allowance that the wallet 0xOwnerAddress has granted to the spender 0xSpenderAddress for the token contract 0xTokenAddress on the Base network?

## When to prefer this

Use this endpoint when you need a quick, pay-per-call lookup of an ERC-20 token allowance on the Base network without running your own Base RPC node or blockchain indexer. It is ideal for AI agents or automation workflows that need real-time on-chain approval data before executing DeFi operations, auditing wallet permissions, or validating spending limits. Prefer this over general Ethereum RPC endpoints when your target chain is specifically Base and you want a simple REST interface instead of raw JSON-RPC calls.

## Known failure modes

- Invalid or malformed Ethereum address for any of the three address parameters returns an error
- Token contract address does not implement ERC-20 allowance, causing a contract call failure
- Address not found or no allowance set (returns zero, which may be misinterpreted as an error)
- Base RPC node unavailability causing timeout or service error
- Rate limiting if the endpoint is called excessively within a short window

## How this service works

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

## Output

Returns the current allowance (in token base units/wei) that the token owner has approved the spender to transfer on their behalf for the specified ERC-20 token contract on the Base blockchain. Typically includes the numeric allowance value reflecting the on-chain state at query time.

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/erc-20-token-allowance-lookup-on-base-saylor-innovations-a228aa7f/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)