> For the complete documentation index, see [llms.txt](https://docs.fathom.fi/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.fathom.fi/dex/architecture.md).

# Architecture

Fathom DEX relies on a robust and secure smart contract architecture to facilitate its decentralized exchange functionalities.

These smart contracts are the [Uniswap V2 direct fork](https://docs.uniswap.org/contracts/v2/concepts/protocol-overview/smart-contracts). They are battle-tested on various networks and are considered safe.

### **Overview of Smart Contract Architecture**

#### **Factory Contract**

* **Role:** The factory contract is responsible for deploying new liquidity pool contracts. It maintains a registry of all active liquidity pools on the platform.
* **Functions:**
  * CreatePair: Deploys a new pair contract for a given token pair.
  * GetPair: Retrieves the address of an existing pair contract.

#### **Pair Contract**

* **Role:** Each pair contract represents a liquidity pool for a specific token pair. It manages the addition and removal of liquidity, as well as the execution of token swaps.
* **Functions:**
  * AddLiquidity: Allows users to add tokens to the liquidity pool.
  * RemoveLiquidity: Allows users to withdraw their tokens from the liquidity pool.
  * Swap: Facilitates token swaps between the two tokens in the pair.

#### **Router Contract**

* **Role:** The router contract provides the main interface for users to interact with the DEX. It routes transactions to the appropriate pair contracts.
* **Functions:**
  * AddLiquidity: Simplifies the process of adding liquidity by automatically calculating the optimal token amounts.
  * RemoveLiquidity: Manages the removal of liquidity, ensuring users receive the correct token amounts.
  * SwapExactTokensForTokens: Executes a token swap with a specified input amount.
  * SwapTokensForExactTokens: Executes a token swap with a specified output amount.


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