# BaseBuilder DeFi Optimal Bridge Gas Estimator

> BaseBuilder DeFi Optimal Bridge Gas Estimator is a paid API for AI agents from bb-defi.vercel.app, paid per call via x402, $0.120765/call, status unknown (last checked 2026-09-14).

Returns the optimal bridging route and gas cost recommendation for cross-chain DeFi token transfers

## Facts

- Endpoint: POST https://bb-defi.vercel.app/api/gas/optimal-bridge
- Price: $0.120765/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-optimal-bridge-gas-estimator-ab88e55e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_DWwlpIWkQ_RgnGbhBg2CV

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-optimal-bridge-gas-estimator-ab88e55e -d '<json body>'
```

Example prompt: What's the optimal bridge route and gas cost for moving 500 USDC from Base to Ethereum mainnet right now?

## When to prefer this

Use this endpoint when you need to determine the most cost-efficient bridge route and gas price for a cross-chain token transfer on Base and EVM-compatible chains; particularly useful before executing a bridge transaction to avoid overpaying on gas or choosing a suboptimal protocol

## Known failure modes

- Unsupported source or destination chain returns 400 with invalid chain error
- Unsupported token pair returns 400 with unsupported asset error
- Amount too small for bridging returns 400 with minimum amount error
- Network congestion causing stale gas data returns 503
- Payment not received or insufficient USDC returns 402 payment required
- Rate limiting if too many requests returns 429

## How this service works

BaseBuilder Defi API hub - 22 paid endpoints

## Output

Returns the recommended bridge protocol, optimal gas price in gwei, estimated transaction fee in USD and native token, and expected confirmation time for the specified cross-chain transfer

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/basebuilder-defi-optimal-bridge-gas-estimator-ab88e55e/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)