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Simulate a Transaction Before Sending

Broadcasting a failing transaction still burns fees. This guide simulates a raw transaction first so you see balance changes and any revert reason before it hits the network. Simulate on every path where a revert or fee shortfall would cost you.

Перед началом

An API key with C2 access for the simulate endpoint.
A built raw transaction from /v1/tx/{chain}/build (or your own encoder).

1Build the transaction

Build a raw payload for the transfer you intend to send. The build endpoint returns the unsigned raw bytes.

curl -X POST https://api.1st-node.com/v1/tx/tron/build \
  -H "Authorization: Bearer sk_live_..." \
  -d '{"from":"TQ1n7...","to":"TR8h2...","amount":"1000000"}'
> {"raw":"0a02...","fee_estimate":"1100000"}

2Simulate the raw transaction

POST the raw payload to /v1/tx/{chain}/simulate. Inspect balance_changes and revert_reason before committing any signature.

curl -X POST https://api.1st-node.com/v1/tx/tron/simulate \
  -H "Authorization: Bearer sk_live_..." \
  -d '{"raw":"0a02..."}'
> {"success":true,"revert_reason":null,
>  "balance_changes":[{"address":"TQ1n7...","delta":"-1000000"}]}

3Branch on the result

If success is false, read revert_reason (for example insufficient energy or an ERC-20 allowance) and fix inputs. Only sign and broadcast a clean simulation.

Частые вопросы

What does simulate return on a failing transaction?

success is false and revert_reason carries the decoded cause — a contract revert string, insufficient fee, or missing energy — so you fix it before spending fees.

Is simulation charged the same as a broadcast?

Simulation is a C2 primitive, the same tier as build, sign and broadcast. It runs against a forked state and never touches the mempool.

Читать дальше

build-sign-and-broadcast-a-transaction ethereum-api /pricing

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