Changes and deprecations in Flashbots Protect RPC

The Flashbots Ship
1

We are deprecating the Whitehat Bundle Cache API, the Custom Ethereum RPC URL query parameter, and unsigned eth_sendPrivateTransaction requests on November 17, 2025 in the Protect API. We’re also unifying rpc.flashbots.net and relay.flashbots.net, and adding JSON-RPC batching support.

Deprecations

Whitehat Bundle Cache API

Impacted endpoints:

  • GET /bundle?id=<YOUR_BUNDLE_ID>
  • URL query parameter ?bundle=<YOUR_BUNDLE_ID>

What to do:

  • Remove use of the Whitehat Bundle Cache API paths and query parameters.

Custom Ethereum RPC URL

Impacted endpoints:

  • URL query parameter ?url=<SOME_ETHEREUM_RPC_URL>

What to do:

  • Remove ?url query parameter that overrides the Ethereum RPC URL.

eth_sendPrivateTransaction (unsigned)

Impacted endpoints:

  • unsigned JSON-RPC eth_sendPrivateTransaction method

What to do:

  • Sign eth_sendPrivateTransaction requests by including the X-Flashbots-Signature header
  • Change parameter formatting. The parameters for the signed method are different with the first parameter being an object, see here for detailed documentation: eth_sendPrivateTransaction | Flashbots Docs

Timeline

Changes take effect on November 17, 2025.

Impact

Regular Protect RPC usage is unaffected. Requests that rely on the Whitehat Bundle Cache API GET /bundle, the ?bundle, unsigned eth_sendPrivateTransaction, or ?url query parameters will stop working. The two API entry points rpc.flashbots.net and relay.flashbots.net now resolve to a single endpoint, reducing developer friction. With JSON-RPC batching, ethers default batching works out of the box.

Support

Please reach out, reply here, or on Telegram (Telegram: Contact @shanejonas) before November 17, 2025 if you have any questions or feedback.