# BaseBuilder DeFi Bridge Swap Rate

> BaseBuilder DeFi Bridge Swap Rate is a paid API for AI agents from bb-defi.vercel.app, paid per call via x402, $0.145638/call, status unknown (last checked 2026-09-14).

Returns the current swap rate for bridging tokens across chains via the BaseBuilder DeFi bridge

## Facts

- Endpoint: POST https://bb-defi.vercel.app/api/bridge/swap-rate
- Price: $0.145638/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/basebuilder-defi-bridge-swap-rate-de44e8f9
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_7hXTwhKe7VWeqPoxUD_OY

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-de44e8f9 -d '<json body>'
```

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

## When to prefer this

Use this endpoint when you need a real-time bridge swap rate quote between two tokens on different chains, specifically when operating within the BaseBuilder DeFi ecosystem or targeting Base chain. Prefer this over generic DEX aggregators when you specifically want bridge rates (cross-chain) rather than same-chain swaps.

## Known failure modes

- Unsupported token pair returns an error or null rate
- Unsupported source/destination chain combination returns error
- Invalid or missing required parameters returns 400 bad request
- Payment not received or insufficient funds returns 402
- Service unavailable or provider downtime returns 503
- Extremely low liquidity may return an unusable rate

## How this service works

BaseBuilder Defi API hub - 22 paid endpoints

## Output

Returns the current exchange/swap rate for bridging the specified token pair across chains, including the expected output amount and any associated bridge fees.

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/basebuilder-defi-bridge-swap-rate-de44e8f9/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from bb-defi.vercel.app](https://www.zero.xyz/host/bb-defi.vercel.app/llms.txt)