# TamaSwap Debuts as a Formally Verified, Fully Onchain DEX

*Author: Bankless*
*Published: May 29, 2026*
*Source: https://www.bankless.com/es/read/news/tamaswap-debuts-formally-verified-dex*

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zefram.eth just [launched TamaSwap](https://x.com/boredGenius/status/2060094391667372464), a decentralized exchange he bills as the first "provably unhackable" DEX, with its security guarantees machine-checked via the Lean proof language and its entire interface living onchain.

> Introducing TamaSwap, the first provably unhackable DEX.- No-free-lunch theorem, machine-checked via Lean- Onchain HTML interface, forever online- No protocol fees, no-code deploy to any EVM chainBuilt with Tama + Verity. AGPL license.The platonic ideal of xy=k. [pic.twitter.com/SldlGzRGJA](https://t.co/SldlGzRGJA)— zefram.eth (@boredGenius) [May 28, 2026](https://x.com/boredGenius/status/2060094391667372464?ref_src=twsrc%5Etfw)

### **What's the Scoop?**
- **Why It Matters:** zefram formalized *unhackable *as a "no-free-lunch theorem," i.e. a mathematical proof that no sequence of actions lets an attacker extract value from a smart contract. Accordingly, TamaSwap, which demos this property in production, rules out most categories of exploits at once. 
- **The Stack:** TamaSwap was built with [Verity](https://veritylang.com/), a new smart contract language designed for provable security, and [Tama](https://tama.tools/), zefram's accompanying dev toolchain (like Foundry, but bespoke for Verity). As such, the deployment doubles as research toward making formal verification practical for more complex apps. 
- **Fully Onchain:** The TamaSwap protocol is immutable, charges zero protocol fees, and can be redeployed to any EVM chain in a single click. The frontend is also notably [itself a contract](https://x.com/boredGenius/status/2060094555295547439) deployed to Ethereum mainnet (per the ERC-4804 + ERC-5219 standards), so the interface has no external dependencies and will be accessible onchain as long as Ethereum runs. 

### **Bankless Take:**
As formal verification is starting to [gain more attention](https://vitalik.eth.limo/general/2026/05/18/fv.html) in Ethereum ecosystem, TamaSwap is a great new proof-of-concept that gives us all a tangible early example of how DeFi security can increasingly come from math and math alone. The project and its surrounding research are threads worth tracking as AI makes both writing proofs and finding bugs much cheaper.