$ transfer.cdc
1 
FlowIndex Simulator

// FEATURES
⎔

Mainnet Fork

Fork real mainnet state via Flow Emulator. Your simulation runs against actual on-chain data.

◫

Snapshot Isolation

Every simulation creates a snapshot, executes, then reverts. Zero side effects.

⊞

Balance Detection

Automatically parses token transfer events to show balance deltas per address.

◉

Zero Risk Preview

See balance changes, events, and errors — before signing anything.

// HOW IT WORKS
01

Write Code

// write or pick a template

02

Simulate

// fork mainnet, execute, revert

03

Verify & Send

// check results, then send for real

// PLAYGROUND

Try it now

Click ▶ Simulate to run↓
Initializing playground...
Simulator
// REST API

Programmatic Access

Use the simulate endpoint directly from your scripts, CI pipelines, or dApps. Full API docs →

$ REQUEST
curl -X POST https://simulator.flowindex.io/api/simulate \
  -H "Content-Type: application/json" \
  -d '{
    "cadence": "transaction(amount: UFix64) { ... }",
    "arguments": [{"type": "UFix64", "value": "10.0"}],
    "authorizers": ["0x1654653399040a61"],
    "payer": "0x1654653399040a61"
  }'
> RESPONSE
{
  "success": true,
  "summary": "Transfer 10.0 FLOW",
  "transfers": [{
    "token": "A.1654653399040a61.FlowToken",
    "amount": "10.00000000",
    "from_address": "0x1654653399040a61",
    "to_address": "0xf8d6e0586b0a20c7",
    "transfer_type": "transfer"
  ],
  "balanceChanges": [
    { "address": "1654653399040a61", "delta": "-10.0" },
    { "address": "f8d6e0586b0a20c7", "delta": "+10.0" }
  ],
  "computationUsed": 1204,
  "fee": 0.00001,
  "tags": ["ft-transfer"],
  "events": [...]
}