The "Write Contract" tab on Routescan allows for direct interaction with smart contracts. While a powerful capability, this carries inherent risks, as live transactions can lead to irreversible errors or a loss of funds.
Executing a "Write" transaction can be unpredictable. A transaction might fail after gas fees have already been spent, or it could succeed but cause an unexpected and negative outcome. This creates uncertainty about a function's true behavior and potential security vulnerabilities. To help mitigate these risks, the first essential step is a detailed review of the smart contract's source code to fully understand what you are interacting with. However, since code can be complex and its final outcome isn't always obvious from reading it alone, you can also simulate the "Write" function before proceeding with a live transaction.
Routescan’s Write Contract Simulation feature is designed to help manage this risk. It allows you to enter your transaction parameters and simulate the call in a secure environment. You can then review detailed outputs to understand contract responses, anticipated state changes, or potential errors—all without expending gas or risking assets. This process reduces uncertainty and empowers you to make informed decisions before interacting onchain. Below, we break down each step and explain how you can use Write Contract Simulation.
How Contract Simulation Works
Write Contract Simulation provides a secure offchain sandbox within the Routescan interface. It runs a function call under the exact same conditions as a live transaction, showing you the outcome without any real-world consequences or costs.
This tool is fundamental for safe blockchain interaction.
Risk-Free outcome preview. See the detailed results and state changes of a transaction before committing.
Preview immediate function behavior. Test functions to see their direct outcome. This can help spot immediately suspicious actions, like a
claimfunction that attempts to transfer your assets instead of giving you tokens.Prevent costly failed transactions. Catch input errors or other issues that would cause a transaction to fail, saving you from wasted gas fees.
No wallet connection needed. You can simulate any function without connecting your wallet, ensuring your assets are never at risk during testing.
ℹ️ Important note: You must not rely on simulation alone to prove a contract is safe or free of malicious logic. Simulation only shows whether a single transaction would succeed or fail under current conditions; it cannot reveal multi-step exploits, hidden admin functions, complex honeypot traps, or future economic attack vectors. Always combine simulation with other due diligence, such as checking for formal audits, reviewing the project's reputation and analyzing smart contract code.
How To Use Simulation
The process is straightforward. Here is how you can simulate a Write Contract function.
Navigate to the Contract
First, go to any verified smart contract on Routescan. It is a recommended best practice to review the verified Contract source code to understand its purpose. For this guide, we'll use this sample contract: https://routescan.io/address/0x138665bdCD8a2DEA184c340a3DB2F1031bAc15dF/contract/8453/code?chainid=8453.
ℹ️ Important note: Please note that the simulation feature does not currently support proxy contracts.
Select "Write Contract"
Click on the Write Contract sub-tab to view all the executable functions. You can simulate any available Write Contract function.
Click "Simulate"
Find the function you wish to test and fill in its parameters. Instead of clicking "Write," click the “Simulate” button. Confirm the “From” address for simulation.
Analyze the Results
A pop-up window will display the simulation's outcome. If the interaction is successful, it will show the confirmation details.
Critically, if the interaction would have failed, the simulation will show you the specific error. This allows you to diagnose the problem—whether with your inputs or the contract's code—without spending any gas. Below are a few possible error outcomes after simulation with different smart contracts.
Common Write Functions and Why You Should Simulate Them
Many smart contracts use a set of common functions. Here are a few popular examples and how simulation helps you use them safely.
approve(address spender, value): Lets a smart contract use your tokens. Simulate it to verify the contract is legitimate and not a malicious scam asking for approval.transfer(address recipient, value): Sends tokens to another address. Simulate it to double-check the recipient's address and amount, preventing irreversible mistakes.claim()orwithdraw(): Collects rewards or airdrops from a contract. Simulate to check the immediate outcome. Be aware this cannot detect complex honeypot scams where theclaimworks but you are unable to sell or transfer the token later.stake(value): Locks tokens in a contract to earn rewards. Simulate it to check for immediate fees or errors, but note that it cannot predict future risks like problems with theunstakefunction.transferOwnership(address newOwner): A high-stakes function that changes the owner of a smart contract. Simulate it to prevent accidentally losing control of the contract forever.
By simulating transactions before execution, you can preview a function's immediate behavior and avoid costly mistakes. The Write Contract Simulation feature is a key tool on Routescan for promoting safer and more predictable smart contract interactions. For better security, always use it in combination with other verification methods, such as reviewing the contract's source code and checking for a formal audit, before executing a live transaction.