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How to Choose a Transaction Simulation Provider

How to Choose a Transaction Simulation Provider

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Written by Alchemy

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Reviewed by Brady Werkheiser

Published on 2023-03-304 min read

As Web3 continues to grow, there is rising popularity of transaction simulator tools to improve user safety. These wallet security tools allow users to simulate Web3 transactions before they sign a transaction, allowing users to test their transactions before committing them to the blockchain.

With multiple transaction simulation choices available, developers must consider many factors before deciding on the right tool for their needs, such as which networks they support, the user experience, and how they handle different signature types.

In this article, we’ll explore how transaction simulation works, its benefits, the different types available, and key factors to consider when selecting a transaction simulation provider.

How does Transaction Simulation work? 

Transaction simulation is the ability to preview how a transaction will behave before authorizing (i.e., signing) it on-chain. By providing human-readable interpretations of transactions, users can be confident that the transaction will behave as intended and expected.

Transaction previewing extensions offer users a virtual environment that mimics the behavior of the mainnet production environment, allowing users to test their transactions before executing them on-chain.

What are the benefits of using Transaction Simulation tools?

Transaction simulation enables users to send transactions confidently by helping them understand how transactions will impact their wallet and digital assets ahead of time. 

This section will explore the benefits of using transaction simulation tools.

1. Increase Security

Transaction simulation tools provide users with an added layer of security. By testing transactions in a virtual environment, users can ensure their transactions are safe, preventing loss of funds.

2. Deepen Learning

Transaction simulators are great learning tools for users new to Web3. Users can experiment with simulators and see how contracts work behind the scenes without risking funds. This helps users learn how Web3 works and how to interact with it.

3. Prevent Errors

Another benefit of transaction simulators is that they help prevent errors. Users can test their transactions on a virtual environment and detect errors before executing them on the mainnet. This helps prevent loss of funds due to transaction errors.

What are the different types of Transaction Simulation tools?

Users can choose between two transaction simulation tools: browser extensions and native transaction previews in Web3 wallets.

Below, we will examine the advantages and disadvantages of each type of tool.

1. Browser Extensions

A browser extension-based transaction simulator is a tool that allows you to simulate every Web3 transaction before signing it in your wallet.

This section will examine a few options, such as Fire, Pocket Universe, Stelo, Wallet Guard, and Blowfish.


Fire is a browser extension that simplifies Web3 by providing a clear preview of what will enter and exit your wallet before you sign a transaction. It supports the simulation of transactions across the four largest EVM chains, including Ethereum, Polygon, Arbitrum, and Optimism.

Additionally, Fire pops up right next to your Web3 wallet so that you can review the simulation of the transaction you are about to sign.

Pocket Universe

Pocket Universe is a free browser extension that keeps your assets safe when you sign Web3 transactions and is available on Ethereum and Polygon.

It pops up before your wallet and allows you to continue or reject a transaction based on the preview before it reaches your Web3 wallet.


Stelo is a browser extension that allows you to preview Ethereum transactions. Like Pocket Universe, Stelo intercepts the transaction before your wallet appears, allowing you to either reject or continue the transaction and send it to your wallet.

Like Fire, Stelo includes price in their extension, and is available on Ethereum Mainnet.

Wallet Guard

Wallet Guard is a security extension featuring transaction previews and proactive phishing detection. Wallet Guard catches the transaction before it is sent to your wallet and works on Ethereum Mainnet.


Blowfish is an extension that keeps users safe from malicious transactions and is equipped with a fraud detection engine and multi-chain support, including Ethereum, Polygon, Solana, BNB Chain, and Arbitrum.

2. Wallet Simulators

Some wallets provide transaction simulation directly in their wallet interface. So, if you are up for downloading a new wallet, these are nice options for you to have.

Coinbase Wallet

Coinbase wallet's transaction preview will show users an estimate of how their token balance(s) will change when they approve a new transaction.

The simulator is in both their wallet extension as well as their mobile wallet on all EVM networks. 


Rabby, an extension and desktop wallet developed by DeBank, displays your upcoming balance change before you sign a transaction. The simulator is integrated into the native wallet itself, appearing at the top of each transaction, and supports all EVM chains.

Factors to Consider When Choosing a Transaction Simulation Tool

With many options for simulating Web3 transactions, there are several factors that you should consider when deciding which option best fits your needs. 

1. Decide on the Type of Tool

Start by assessing your product’s requirements. Can you integrate into your user experience a wallet that has simulation functionality baked directly into the user experience?

If not, consider finding a browser extension that is compatible with the chains on which your app is deployed and the wallets with which your app is integrated.

2. Evaluate the Team

When planning for the future, it's good to consider the people building the tools.

  • Do they have a proven track record on other web3 apps?

  • Do they have enough people on the team to support the breadth of their mission?

  • Do they have enough engineers to continue to innovate and quickly fix bugs?

Consider the complexity of their tools and their level of community support in the context of these questions.

3. Review Code Audits

It is best practice to choose dev tools that have been subjected to strict code and security audits to ensure that they are safe and reliable.

Network architecture, system configuration, access controls, and other verifiable, security-related components can become crucial to a tool’s long-term effectiveness.

4. Map Solutions to Your Use Case

Accuracy, clarity, and ease of use come into play when evaluating options for transaction previewing tools. It is crucial to optimize based on your intended use case and your requirements for data comprehensiveness. Here are three potential solutions based on common use cases:

Simulate Asset Changes

For teams that only need to preview asset changes, alchemy_simulateAssetChanges will provide sanitized and simplified simulation data to quickly discern a transaction's asset deltas before it is executed. This is often particularly useful for wallet developers.

Simulate Transaction Execution

For teams that need (and have the processing power to utilize) more transaction preview details, alchemy_simulateExecution provides end-to-end simulation (inclusive of ABI decoded results and comprehensive logs, events, and trace data) of a transaction’s expected results.

This is particularly useful for lending protocols, security products, smart contract developers, and DEXs. 

Simulate Transaction Bundles

Teams that need to understand the impact of sequential transactions, or transactions whose results are predicated on the results of a previous transaction, will benefit from alchemy_simulateAssetChangesBundle or alchemy_simulateExecutionBundle.

NFT marketplaces that want to ensure that an NFT is transferable in a purchase or decentralized exchanges (DEXs) that need to prevent one-way swaps would benefit from products with integrated Bundled Simulation tools.

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