Simulate a transaction before signing
Simulate a transaction before signing: runs `eth_estimateGas` for `{ to, from?, data?, value? }` and returns the estimated gas units and estimated fee (current gas price x gas, in wei + ETH). If the node rejects the call it returns `ok:false` with the decoded `revertReason` (why it would fail) instead of erroring. Reads live on-chain state with automatic endpoint fallback.
Answeringour last check, 2026-09-24
1 of 1checks answered this week
459 msmedian answer time
$0.004listed price per call
$0.004price it asked us
Paid test badge: not yet. The checks above are free: we call the tool without paying and read the payment request it sends back. The Verified badge needs paid calls whose answers match the promised output, and nobody can buy a badge.
Endpoint
POST https://chain.openverbs.com/v1/gas-estimate
| Category | Market data |
|---|---|
| Provider host | chain.openverbs.com |
| Networks | eip155:8453 |
| Payment schemes | exact |
| Self-reported calls, 30 days | 2 from 1 payers (the provider's figure, not ours) |
Our checks, last 30 days
| Day | Result | HTTP | Asked | Time |
|---|---|---|---|---|
| 2026-09-24 | valid payment request | 402 | $0.004 | 459 ms |
Example input (from the provider)
{
"body": {},
"bodyType": "json",
"method": "POST",
"type": "http"
}
Promised output schema (from the provider)
{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"properties": {
"input": {
"additionalProperties": false,
"properties": {
"body": {
"additionalProperties": false,
"properties": {
"chain": {
"description": "EVM chain to query. One of: ethereum, base, arbitrum, optimism, polygon. Default \"ethereum\".",
"enum": [
"ethereum",
"base",
"arbitrum",
"optimism",
"polygon"
],
"type": "string"
},
"data": {
"description": "Calldata hex (optional; e.g. an ERC-20 transfer).",
"pattern": "^0x([0-9a-fA-F]{2})*$",
"type": "string"
},
"from": {
"description": "Sender address (optional; affects state-dependent estimates).",
"pattern": "^0x[0-9a-fA-F]{40}$",
"type": "string"
},
"to": {
"description": "Destination address (contract or wallet).",
"pattern": "^0x[0-9a-fA-F]{40}$",
"type": "string"
},
"value": {
"description": "Native value in wei, decimal or 0x-hex (optional).",
"type": "string"
}
},
"type": "object"
},
"bodyType": {
"enum": [
"json",
"form-data",
"text"
],
"type": "string"
},
"method": {
"enum": [
"POST"
],
"type": "string"
},
"type": {
"const": "http",
"type": "string"
}
},
"required": [
"type",
"method",
"bodyType",
"body"
],
"type": "object"
}
},
"required": [
"input"
],
"type": "object"
}