Only this contract
Chainhook reports OP transfers from 0x4200000000000000000000000000000000000042 only. Tokens on OP Mainnet that copy the OP name or symbol are ignored, so a spoofed deposit never reaches your endpoint.
OP Mainnet OP transfer notifications, delivered as webhooks
Get a signed webhook when a OP Mainnet address sends or receives Optimism (OP). Chainhook waits 20 blocks, about 40 seconds, then posts the transfer to your endpoint.
OP on OP Mainnet at a glance
The contract Chainhook watches, how amounts are scaled, and how long OP takes to reach your endpoint.
- Token
- Optimism (OP)
- Network
- OP Mainnet
- Contract
0x4200000000000000000000000000000000000042- Decimals
- 18
- Confirmations
- 20
- Time to webhook
- About 40 seconds
How OP ERC-20 webhooks work
OP Mainnet produces a block every 2 seconds. Instead of polling an RPC for every address, register the address once and Chainhook pushes each confirmed transfer to you after 20 blocks.
Register the address
Create a webhook with
network: "optimism",type: "token"and the address you want to watch. The signing secret is returned once.Chainhook waits for confirmations
Every OP Mainnet block is scanned. A matching OP transfer is held until it is 20 blocks deep, about 40 seconds.
Your endpoint gets a signed POST
A
transfer.detectedevent arrives with anX-Webhook-Signatureheader. Failed attempts are retried automatically, up to 3 attempts in total, waiting 1 minute, then 5 minutes between attempts.
POST /v1/webhooks
{
"network": "optimism",
"type": "token",
"direction": "in",
"address": "0x70598e346eb9a0653f0319cbce139f5a03e00d98",
"webhook_url": "https://api.example.com/webhooks/chainhook"
}Sample webhook payload
What your endpoint receives for an incoming OP transfer on OP Mainnet. amount is already scaled by decimals; amount_raw is the on-chain integer.
OP on OP Mainnet
POST /webhooks/chainhook HTTP/1.1 Host: api.example.com Content-Type: application/json User-Agent: chainhook/1.x X-Webhook-Id: 01a0fbfd-4fe4-7a3c-8f21-6b9d0e4c7a15 X-Webhook-Signature: 7a12d02673420517279805cf8188a1a62c6f69706161ba5cf0a8ec91ea66b8e3 { "id": "01a0fbfd-4fe4-7a3c-8f21-6b9d0e4c7a15", "event": "transfer.detected", "created_at": "2026-10-02T09:41:17Z", "webhook_id": "01a0fbf2-fadc-7c3e-9b1a-4d6f2e8a5c71", "data": { "network": "optimism", "direction": "in", "type": "token", "transaction_hash": "0xde65ec4246332db41cca7eef7001f80e2064bcd1bb4abb3924188bf4c9e32a19", "transfer_index": 9, "block_number": 158495252, "block_hash": "0x6d7a74b7c7cad66be99411a890577972934996cdce9e78cc56ec7d7ddf2d5f00", "block_timestamp": "2026-10-02T09:41:05Z", "confirmations": 20, "from": "0x5bf5a1da194ed738308ecbfcfa38f6e1dc50ace5", "to": "0x70598e346eb9a0653f0319cbce139f5a03e00d98", "currency": "OP", "amount": "1000", "amount_raw": "1000000000000000000000", "decimals": 18, "contract_address": "0x4200000000000000000000000000000000000042" } }
Verify the signature
X-Webhook-Signature is a hex HMAC-SHA256 of the raw body, keyed with your webhook's secret. Reject any request where it doesn't match.
import crypto from 'node:crypto'; import express from 'express'; const app = express(); app.post( '/webhooks/chainhook', express.raw({ type: 'application/json' }), (req, res) => { const signature = req.get('X-Webhook-Signature') ?? ''; const expected = crypto .createHmac('sha256', process.env.CHAINHOOK_SIGNING_SECRET) .update(req.body) .digest('hex'); const valid = signature.length === expected.length && crypto.timingSafeEqual(Buffer.from(signature), Buffer.from(expected)); if (!valid) { return res.sendStatus(401); } const event = JSON.parse(req.body); // Skip event.id if you've already processed it. res.sendStatus(200); }, );
Crediting OP deposits safely
18 decimals
OP on OP Mainnet uses 18 decimals. Credit the amount string, or scale amount_raw by decimals; never parse amounts as floating-point numbers.
Payments, deposits or holdings
Use direction: "in" for incoming OP, "out" for withdrawals, or "any" to follow every movement on the address.
Credit once per transfer
Delivery is at least once. Store the event id, or transaction_hash with transfer_index, and skip events you have already processed.
More on OP Mainnet and OP
Pay per detection
Start with 100 trial detections for 1 month and pay only for what you use. Paid plans add detections, webhooks, and per-detection overage.
Pay as you go
$0/month
Card required, no monthly fee
- 100 trial detections for 1 month
- 3 active webhooks
- $0.001 per detection after the trial
- Decoded transfers, delivered once confirmed
Starter
$9/month
or $90/year billed yearly
- 25,000 detections a month
- 25 active webhooks
- $0.0006 per extra detection
- Decoded transfers, delivered once confirmed
- Recommended
Growth
$29/month
or $290/year billed yearly
- 100,000 detections a month
- 100 active webhooks
- $0.0003 per extra detection
- Decoded transfers, delivered once confirmed
Scale
$99/month
or $990/year billed yearly
- 400,000 detections a month
- 200 active webhooks
- $0.0002 per extra detection
- Decoded transfers, delivered once confirmed
Enterprise
Custom limits for teams that need more than 400,000 detections a month or more than 200 active webhooks. Contact us and we'll set up a plan around your volume.
Prices in USD, plus applicable tax. Billed monthly or yearly, and paid allowances reset monthly. Cancel any time and keep your plan until the period ends.
OP on OP Mainnet questions
Can't find your answer? Contact support.
What is the OP contract address on OP Mainnet?
0x4200000000000000000000000000000000000042, with 18 decimals.
How do I detect an incoming OP transfer on OP Mainnet?
Create a webhook with network: "optimism", type: "token", direction: "in" and the receiving address. Each confirmed OP transfer arrives as a transfer.detected event.
How long until a OP transfer is reported?
About 40 seconds. Chainhook waits 20 blocks on OP Mainnet before it sends the event.
Does Chainhook need my private key?
No. Chainhook only reads public blockchain data. You register a public address and receive events about it.
Watch your first wallet
Create an account and start with 100 trial detections for 1 month.