Wallet security used to be about one thing: don’t lose your seed phrase. In 2026, that’s still true—but it’s not the main way people lose money.
Now the most common disasters are “I signed something” moments: a fake approval, a malicious contract interaction, a confusing signature prompt, or a wallet drainer that empties tokens before you even realize what happened.
That’s why a simple idea is gaining momentum: transaction simulation—showing you what a transaction will actually do before it hits the blockchain. ForkLog reported that Ethereum co-founder Vitalik Buterin called for transaction simulation to be integrated into crypto wallets and smart contracts, framing security and user experience as basically the same goal: reducing the gap between what the user intends and what the system actually does.
This article explains what that means in plain English, why simulation can block common wallet drainers, how it works technically, where it’s already being used, and what it can’t protect you from.
What is transaction simulation?
A transaction simulation is a “dry run” of your transaction in a virtual environment that mirrors the latest blockchain state. It predicts outcomes such as:
- which tokens will move (and how many)
- whether approvals are being granted
- whether a contract call will fail
- how balances might change after execution
Tenderly describes its “Transaction Preview” as a way for dapps and wallets to preview outcomes before executing on the live network, using simulation in an environment that mimics the latest chain state.
In normal life, you already expect previews everywhere:
- your bank app shows “You’re about to send $200 to X”
- your email client shows a draft before you hit send
- your phone asks “Are you sure?” before deleting 1,000 photos
Crypto, oddly, often asks users to sign “data blobs” with minimal context. Simulation is a way to give users the preview they should’ve had from day one.
Vitalik’s core argument: security is about “intent,” not just code
ForkLog’s coverage highlights Buterin’s framing: the goal of security is to minimize the divergence between user intent and system behavior—and that UX can be defined the same way.
His proposed flow is simple:
- the user indicates what they want to do
- the wallet simulates the on-chain consequences
- the user taps “OK” or “Cancel” after reviewing the preview
Buterin also points out that “perfect security” is impossible because user intent is fundamentally hard to define, even for the user themselves. His answer is redundancy—users express intent in multiple overlapping ways, and the system only proceeds when they match.
He also suggests LLMs could act as an “additional filter” that approximates human common sense, especially if customized to a specific user.
That’s the theory. What about practice?
How transaction simulation stops common wallet-drainer patterns
Most wallet drainers rely on one of these tricks:
1) “Unlimited approval” bait
A malicious site persuades you to approve a token allowance (sometimes unlimited), enabling later drains.
A simulation can flag:
- “You are granting approval to spend token X”
- “Allowance amount: unlimited”
- “Contract address: unknown / risky”
2) Hidden transfers inside contract calls
Some transactions “look” like you’re minting or claiming something, but the actual call triggers a transfer of assets out.
A simulation can reveal:
- outgoing transfers
- balance changes
- unexpected recipient addresses
3) MEV and transaction failures
Not every problem is malicious—some are just expensive and annoying. Transactions fail due to slippage, gas issues, or state changes. Simulations can reduce failed transactions and predict outcomes.
MetaMask’s “Smart Transactions” feature says each smart transaction is pre-simulated to improve predictability and outcomes, improving success rates and visibility.
Where transaction simulation already exists in 2026
This isn’t a sci-fi concept. Pieces of it are already live.
MetaMask: pre-simulation + security alerts
MetaMask says Smart Transactions are pre-simulated using a “just-in-time simulation service,” designed to provide more predictability and visibility.
MetaMask’s security reporting also states it protects users against certain scams through transaction simulations that warn users when they’re about to interact with known malicious contracts.
And MetaMask support materials describe automated checks and simulations each time you transact, with in-app alerts when something is deemed unsafe.
Tenderly: simulation tooling for wallets and dapps
Tenderly documents Transaction Preview as a wallet/dapp integration that dry-runs transactions against recent chain state to produce realistic previews.
Tenderly even publishes a guide and code resources to integrate transaction previews into wallets like Rabby.
Rabby-style UX: previews and risk scanning
Rabby’s ecosystem is frequently associated with transaction previews and pre-transaction risk scanning (the general concept is widely discussed in wallet review material and integrations).
The limits: what simulation can’t guarantee
Transaction simulation is powerful, but it’s not magic.
1) Simulations depend on state—and state can change
Your simulation uses “current” blockchain state. But between simulation and inclusion in a block:
- prices move
- liquidity changes
- contract state changes
- you get front-run
This is why smart wallets often combine simulation with other systems (private relays, better routing, slippage protection, etc.). MetaMask’s Smart Transactions concept, for instance, isn’t only “simulate and pray”—it’s also about improved transaction handling beyond the public mempool.
2) A malicious contract can behave differently than expected
Some contracts can be designed to behave one way under certain conditions and another way later. Simulation helps, but you still need:
- reputable sources
- contract verification
- caution with brand-new dapps
3) Intent recognition is hard
Buterin himself calls accurately identifying user intent “extremely difficult.”
Even with an LLM, the model can only guess what you meant—so redundancy and explicit confirmations remain important.
Practical safety checklist
If you want to benefit from this “simulation-first” approach right now:
- Prefer wallets that show balance-change previews
If you don’t see “what you send / what you receive,” slow down. - Treat token approvals as dangerous by default
If a simulation shows unlimited allowance, ask yourself: Do I need unlimited?
When in doubt, approve the smallest amount or use permission managers later. - Use simulation tools for high-stakes transactions
For large transfers or DeFi interactions, use transaction preview/simulation tooling when available. - Don’t ignore warnings
If your wallet flags a risky contract interaction, assume it’s risky until proven otherwise. - Add redundancy (Buterin’s “three-factor” idea, simplified)
Before signing, confirm three things match:
- your intent (what you think you’re doing)
- expected result (previewed outcome)
- acceptable risk (amount at stake, counterparty trust)
This aligns closely with the “intent + expected result + risk tolerance” framing described in Buterin’s view.
Conclusion
Wallet drainers thrive on confusion. Transaction simulation fights confusion with clarity.
Vitalik Buterin’s argument, as covered by ForkLog, is that wallets should make users safer by validating intent through transaction simulation and redundant confirmations—possibly even using LLMs as a “common sense” filter.
And the industry is already moving: MetaMask describes pre-simulation as part of Smart Transactions and its broader security approach, while Tenderly provides transaction preview tooling designed for wallet and dapp integrations.
In 2026, the “best wallet” isn’t just the one with the nicest UI. It’s the one that helps you answer one question before you sign.