Config

Public endpoint exposing the per-chain V2 contract addresses ButterPay is running against. Useful for client-side flows (the public subscribe page, the SDK, custom integrations) that need to know which SubscriptionManager / PayRouter to interact with — without baking addresses into your build.

Authenticated intent endpoints (POST /v1/merchants/register-intent, POST /v1/plans, POST /v1/subscriptions/:id/cancel) already include the to contract address in their response, so most server-side integrators won't need to call this endpoint directly.

GetConfig

Return the chains and contract addresses currently active in the deployment.

• Path: /v1/config
• Method: GET
• Auth: none (public)
• Use cases:
  • Public subscribe pages (/subscribe/{planId}) — need subscriptionManager to construct ERC-20 approve + subscribe(bytes32) calls
  • SDKs / dApps embedding ButterPay — replaces shipping NEXT_PUBLIC_V2_PAY_ROUTER_* / NEXT_PUBLIC_V2_SUB_MGR_* env vars
  • Healthchecks confirming a deployment is wired to the right contracts

Request

curl https://api.butterpay.io/v1/config

Response

{
  "chains": {
    "42161": {
      "chainId": 42161,
      "name": "Arbitrum",
      "payRouter": "0x5FbAc17B617b34c6D27723B3A0A588A11099D347",
      "subscriptionManager": "0x96039F9bBDe549882ff2ABCBCd95FF666FFf2030",
      "authorityManager": null
    }
  }
}

The top-level chains object is keyed by decimal chainId as a string. Iterate Object.values(response.chains) if you don't know which chains are active in advance.

Field reference

Behavior

• Chains with no contracts deployed are omitted. If you only see 42161 in the response, mainnet is the only active chain in this deployment. Don't assume Sepolia is also there.
• null payRouter / authorityManager are explicit. They mean "no contract deployed on this chain in this env", not "unknown".
• Cache freely. The response only changes when ButterPay deploys new contract addresses (rare). A 5-minute client cache is reasonable; a reload on app start is fine for most apps.
• No auth header is needed. Sending Authorization or X-API-Key is not an error, but is ignored.

Example: building a subscribe transaction client-side

import { encodeFunctionData, createPublicClient, http } from "viem";
import { arbitrum } from "viem/chains";

// 1. Look up SubscriptionManager address for the plan's chain
const cfg = await fetch("https://api.butterpay.io/v1/config").then(r => r.json());
const chain = cfg.chains[String(plan.chainId)];
if (!chain) throw new Error(`Chain ${plan.chainId} not configured`);
const subMgr = chain.subscriptionManager;

// 2. ERC-20 approve(subMgr, amount * cycles)
const approveData = encodeFunctionData({
  abi: ERC20_ABI,
  functionName: "approve",
  args: [subMgr, BigInt(plan.amount) * 12n], // 12 cycles of headroom
});
await wallet.sendTransaction({ to: plan.tokenAddress, data: approveData, chainId: plan.chainId });

// 3. SubscriptionManager.subscribe(bytes32 planId)
const subscribeData = encodeFunctionData({
  abi: SUBSCRIBE_ABI,
  functionName: "subscribe",
  args: [plan.onChainPlanId],
});
await wallet.sendTransaction({ to: subMgr, data: subscribeData, chainId: plan.chainId });

The SDK (@butterpay/core) wraps this pattern via api.config.get().

Errors

This endpoint does not error under normal operation. It returns 200 with an empty chains object only if the backend has been started without any V2_* contract env vars configured (a misconfiguration; the listener will also have logged [v2] No V2 contracts configured).