Incline · · 21 min
How Tenderly Simulates Smart Contracts Before Money Moves Onchain
With 
Nebojsa Urosevic
Key takeaways
Tenderly has run more than 4 billion simulations over eight years and covers more than 100 blockchains.
Nebojsa Urosevic describes Tenderly as a simulation company that models onchain actions against live chain state before any capital or customer is exposed.
The platform sits behind Aave, Uniswap and Safe, and Urosevic argues it is needed because onchain errors cannot be reversed the way bank transactions can.
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0:00Teams such as Uniswap and Safe come up early1 of 6
Summary
Co-founder Nebojsa Urosevic says onchain operations have no undo button, so Tenderly models each action against live chain state before money moves.
Tenderly has run more than 4 billion simulations over eight years and now covers more than 100 blockchains, according to co-founder Nebojsa Urosevic. He describes the company as a simulation business for onchain operations, testing an action against live chain state before any capital or any customer is exposed.
From hackathon to infrastructure
Nebojsa Urosevic co-founded Tenderly in Belgrade in 2018, out of a hackathon project, after working at GoDaddy and Decenter. He is the company's Co-Founder and SVP of Engineering.
Tenderly now sits behind Aave, Uniswap and Safe. Over eight years it has run more than 4 billion simulations, and it covers more than 100 blockchains.
“The reason it exists is that there is no undo button. A bank has recall, reconciliation and a settlement desk, while onchain a wrong address means the money is gone, an approval can drain a wallet legitimately by the rules someone signed, and a changed lending parameter cascades into liquidations.”
Nebojsa UrosevicSimulating before exposure
Urosevic says the core idea is to model an action against live chain state before it touches real funds. In his framing, Tenderly exists so that capital and customers are not exposed until an operation has been tested against the actual state of the chain.
No undo button onchain
Nebojsa Urosevic puts the reason for the company's existence plainly: there is no undo button. He contrasts blockchains with banks, which have recall, reconciliation and a settlement desk to fix mistakes after the fact.
Onchain, he says, a wrong address means the money is gone. An approval can drain a wallet legitimately under the rules someone signed, and a changed lending parameter at a protocol such as Aave can cascade into liquidations.
Urosevic presents simulation as a stand-in for the safety nets banks already have. Because onchain mistakes cannot be reversed, Tenderly tests actions before they happen, and by his account it has done that more than 4 billion times across more than 100 blockchains.
Safe and Uniswap come up most.
- People
- Nebojsa Urosevic
- Companies
- Safe
- Uniswap
- Tenderly
- Aave
- Decenter
- GoDaddy
- Dfns
- Gnosis Safe
