> ## Documentation Index
> Fetch the complete documentation index at: https://bridge.near.tools/llms.txt
> Use this file to discover all available pages before exploring further.

# OmniAddress Format

> Cross-chain address format used throughout the SDK

The SDK uses a unified address format called OmniAddress. It's simple: a chain prefix, a colon, and the native address.

```
<chain>:<address>
```

## Examples

| Chain     | OmniAddress                                        |
| --------- | -------------------------------------------------- |
| Ethereum  | `eth:0x1234567890123456789012345678901234567890`   |
| Base      | `base:0x1234567890123456789012345678901234567890`  |
| Arbitrum  | `arb:0x1234567890123456789012345678901234567890`   |
| Polygon   | `pol:0x1234567890123456789012345678901234567890`   |
| BNB Chain | `bnb:0x1234567890123456789012345678901234567890`   |
| NEAR      | `near:alice.near`                                  |
| Solana    | `sol:EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v` |
| Bitcoin   | `btc:bc1qxy2kgdygjrsqtzq2n0yrf2493p83kkfjhx0wlh`   |
| Zcash     | `zec:t1Rv4exT7bqhZqi2j7xz8bUHDMxwosrjADU`          |

## Chain Prefixes

| Prefix | Chain           | Chain ID (mainnet) |
| ------ | --------------- | ------------------ |
| `eth`  | Ethereum        | 1                  |
| `base` | Base            | 8453               |
| `arb`  | Arbitrum One    | 42161              |
| `pol`  | Polygon PoS     | 137                |
| `bnb`  | BNB Smart Chain | 56                 |
| `near` | NEAR Protocol   | —                  |
| `sol`  | Solana          | —                  |
| `btc`  | Bitcoin         | —                  |
| `zec`  | Zcash           | —                  |

## Tokens Use The Same Format

Token addresses are also OmniAddresses:

```typescript theme={null}
// USDC on Ethereum
"eth:0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48"

// USDC on Solana
"sol:EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v"

// wNEAR on NEAR
"near:wrap.near"
```

## Native Tokens

For native tokens (ETH, SOL, etc.), use the zero address or default representation:

| Chain      | Native Token Address                             |
| ---------- | ------------------------------------------------ |
| EVM chains | `eth:0x0000000000000000000000000000000000000000` |
| Solana     | `sol:11111111111111111111111111111111`           |

## Utility Functions

The SDK provides helpers for working with OmniAddresses:

```typescript theme={null}
import { getChain, getAddress, omniAddress, ChainKind } from "@omni-bridge/core"

// Parse an OmniAddress
const addr = "eth:0x1234567890123456789012345678901234567890"
const chain = getChain(addr)    // ChainKind.Eth
const raw = getAddress(addr)    // "0x1234567890123456789012345678901234567890"

// Create an OmniAddress
const omni = omniAddress(ChainKind.Eth, "0x1234...")  // "eth:0x1234..."

// Check chain type
import { isEvmChain } from "@omni-bridge/core"

isEvmChain(ChainKind.Eth)   // true
isEvmChain(ChainKind.Base)  // true
isEvmChain(ChainKind.Near)  // false
```

## ChainKind Enum

For programmatic use, the SDK provides a `ChainKind` enum:

```typescript theme={null}
enum ChainKind {
  Eth = 0,
  Near = 1,
  Sol = 2,
  Arb = 3,
  Base = 4,
  Bnb = 5,
  Btc = 6,
  Zcash = 7,
  Pol = 8
}
```

## Validation

`validateTransfer()` automatically validates addresses. Invalid addresses throw a `ValidationError`:

```typescript theme={null}
try {
  await bridge.validateTransfer({
    token: "eth:0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48",
    sender: "eth:not-a-valid-address",  // Invalid!
    recipient: "near:alice.near",
    amount: 1_000_000n,
    fee: 0n,
    nativeFee: 0n,
  })
} catch (error) {
  // ValidationError with code "INVALID_ADDRESS"
}
```