Base Contract Type and Proxy DetectionGET /v1/base/contract-type · x402 API by base-onchain-tools

Identify what a Base contract actually is: ERC-20, ERC-721 or ERC-1155 via ERC-165, plus proxy detection across EIP-1967, EIP-1822 and the legacy ZeppelinOS slot, with the current implementation address and a warning when behaviour is upgradeable. Query param: address.

https://base-onchain-tools.dolerite.workers.dev/v1/base/contract-type

What does this x402 API do?

Base Contract Type and Proxy Detection. This is an x402-gated GET API resource from base-onchain-tools. TOLL·402 confirmed a protocol-valid HTTP 402 quote on 2026-08-25. The listing records $0.002 USD-denominated per request on Base. No settled paid call has been verified.

Published price: $0.002 USD-denominated per request
Networks: Base
Latest evidence: TOLL·402 confirmed a protocol-valid HTTP 402 quote on 2026-08-25
Resource ID: 4ac1c4480cc424249b34b926

USE THIS RESOURCE

Start with a quote-only recipe. Payment signing stays in your project.

CODE

AI CODING TOOLS

quote-check.ts

const response = await fetch("https://base-onchain-tools.dolerite.workers.dev/v1/base/contract-type", {
  method: "GET",
});

console.log(response.status);
console.log(Object.fromEntries(response.headers));
console.log((await response.text()).slice(0, 1000));

// A valid 402 is a quote, not a completed paid call.

This sends no payment. Inspect the 402 response before adding a wallet-enabled client.

JSON ↗developer docs →

STATUS HISTORY

JSON RSS

Live 402 quote confirmed2026-08-25 05:21 UTC
GET returned a protocol-valid 402 quote (402). No payment was made.
Origin reachable2026-08-25 05:20 UTC
HEAD https://base-onchain-tools.dolerite.workers.dev/ returned 200.
Observed in 402-index2026-08-25 05:19 UTC
Discovered through self-registered.
Registry record checked2026-08-25 01:10 UTC
Registry health: healthy.

What evidence supports this listing?

402-indexobserved 2026-08-25 · open source record ↗

origin checkHEAD https://base-onchain-tools.dolerite.workers.dev/ → 200 on 2026-08-25

route quotelive 402 quote confirmed · GET 402 · 2026-08-25

Each record has an exact-route quote outcome. Unresolved templates and potentially mutating methods are labeled instead of being invoked without provider-specific test input. A quote is still separate from a settled paid call. Read the discovery and verification methodology →

Which networks and payment options does it accept?

The normalized listing price is $0.002 USD-denominated per request. Raw protocol requirements remain visible below for implementation and audit use.

Baseexact2000 atomic · 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913