# BaseBuilder DeFi Bridge Swap Rate

> BaseBuilder DeFi Bridge Swap Rate is a paid API for AI agents from bbx-defi.vercel.app, paid per call via x402, $0.145638/call, status unknown (last checked 2026-10-09).

Returns the exchange rate for swapping tokens across blockchain bridges in DeFi protocols

## Facts

- Endpoint: POST https://bbx-defi.vercel.app/api/bridge/swap-rate?utm_source=zero.xyz
- Price: $0.145638/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-09
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/basebuilder-defi-bridge-swap-rate-a4407303
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_JeSIUhjrIOcpm0_uLdpXS

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability basebuilder-defi-bridge-swap-rate-a4407303 -d '<json body>'
```

Example prompt: What's the current bridge swap rate for converting 1 ETH from Ethereum mainnet to USDC on Base chain?

## When to prefer this

Use this endpoint when you need a real-time or near-real-time exchange rate quote for a cross-chain token bridge swap, especially within the BaseBuilder DeFi ecosystem covering Base chain and EVM-compatible networks. Prefer this over on-chain direct queries when you want a fast, off-chain rate estimate before committing to a transaction.

## Known failure modes

- Unsupported token pair returns an error or empty rate
- Unsupported source or destination chain returns a 400 or 404
- Network congestion may cause stale or unavailable rate data
- Invalid token contract addresses produce validation errors
- Payment failure (402) if USDC payment not properly attached
- Rate may be temporarily unavailable if bridge liquidity is insufficient

## How this service works

BaseBuilder Defi API hub - 22 paid endpoints

## Output

Returns the current exchange rate for the requested token pair and chain combination, including the estimated output amount, bridge fees, and any applicable slippage or spread information for the cross-chain swap.

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/basebuilder-defi-bridge-swap-rate-a4407303/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from bbx-defi.vercel.app](https://www.zero.xyz/host/bbx-defi.vercel.app/llms.txt)