{"slug":"chain-openverbs-com-v1-gas-estimate-43c5f1","title":"Simulate a transaction before signing","host":"chain.openverbs.com","method":"POST","resource":"https://chain.openverbs.com/v1/gas-estimate","category":"market","description":"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) inste","price_listed":0.004,"price_asked":0.004,"state":"answering","state_label":"Answering","checks_7d":1,"answered_7d":1,"latency_ms_median":459,"reported_calls_30d":2,"reported_payers_30d":1,"networks":["eip155:8453"],"badge":"unverified","paid_checks_7d":0,"paid_ok_7d":0,"example_input":{"body":{},"bodyType":"json","method":"POST","type":"http"},"output_schema":{"$schema":"https://json-schema.org/draft/2020-12/schema","properties":{"input":{"additionalProperties":false,"properties":{"body":{"additionalProperties":false,"properties":{"chain":{"description":"EVM chain to query. One of: ethereum, base, arbitrum, optimism, polygon. Default \"ethereum\".","enum":["ethereum","base","arbitrum","optimism","polygon"],"type":"string"},"data":{"description":"Calldata hex (optional; e.g. an ERC-20 transfer).","pattern":"^0x([0-9a-fA-F]{2})*$","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"},"history":[{"day":"2026-09-24","reachable":true,"status":402,"valid_402":true,"asked_usdc":0.004,"price_match":true,"latency_ms":459,"error":null}],"description_full":"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.","last_updated":"2026-09-20T08:38:28.186Z","schemes":["exact"]}