Public devnet

Disclaimer: Content created from source code using generative AI. Contact us for clarifications or if you find mistakes in this document.

A public, demonstration-only devnet for trying Frame Transactions and the Alternative Mempool. It runs an ethrex fork (execution) with Lighthouse (consensus), plus the sidecar as the mempool and relay.

This is a throwaway network. It has no security model, no faucet and no persistence guarantee, and may be reset at any time. Do not send anything of value to it. Several admin surfaces are deliberately left open.

Endpoints

Execution RPC (ethrex)	https://altmempool.forshtat.com
Mempool RPC (sidecar)	https://altmempool.forshtat.com/rpc
Sidecar WebSocket	wss://altmempool.forshtat.com/rpc
Chain ID	1337 (0x539)
Block time	6 seconds
Explorer	explorer.altmempool.wtf

(TBD: the sidecar README links an explorer at altmempoolexplorer.forshtat.com. The landing page links explorer.altmempool.wtf.)

Both HTTPS routes accept POST with a JSON-RPC 2.0 body and send permissive CORS headers.

• The root URL talks to ethrex. Use it for standard eth_*, net_*, web3_* and txpool_* methods, for legacy and 1559 transactions, and for the ethrex_* and debug_* methods.
• /rpc talks to the sidecar. Use it to submit Frame Transactions into the Alternative Mempool and to follow them. The sidecar also proxies a whitelist of standard read methods to ethrex.

Getting funds

There is no faucet. One account is funded at genesis, and its key is published on purpose in the sidecar repository (deploy/devnet/genesis.values.env). Everyone shares it, so nonce collisions are possible. Generate your own key and fund it once from the shared account with a plain transfer. The workshop’s step_1_check does this for you. Never use the shared key on a real network.

Plain transfers need more gas

The network runs the Amsterdam+ resource-based gas model. A transfer to a brand-new account costs an extra 183,600 state gas, so gas: 21000 fails. Budget at least 204,600 gas. 250,000 is comfortable. A transfer to an existing account still costs 21,000.

Life of a Frame Transaction

1. A client calls eth_sendFrameTransaction on the sidecar.
2. The sidecar makes one ethrex_simulateFrameTransaction call with tracing, recognizes the validation prefix shape, and enforces the rules per role.
3. The transaction enters the sidecar’s mempool and is gossiped to other sidecars over libp2p.
4. In auto mode the sidecar relays it to the local ethrex node through ethrex_submitPrivilegedFrameTransaction.
5. Once a block includes it, the sidecar reads the receipt and sets the status to OnChain or Reverted.

ethrex’s own mempool is not the Alternative Mempool. A Frame Transaction can also be sent to ethrex directly with eth_sendRawTransaction (type 0x06), where ethrex applies the canonical rules.

Predeployed contracts

Real mainnet contracts are deployed on the devnet by replaying their deployment transactions, including LINK, USDT, BAYC, Tornado Cash (0.1 ETH pool), USDC, WETH9, Permit2, Uniswap v4 and Railgun. A NaiveStakingRegistry implementing IStakingRegistry is deployed at 0xd51c04d7a0b01124e84de152f4e56d9eecb22d2f. The full list with addresses is in the sidecar repository, deployments/devnet.md. Addresses can change when the devnet is reset.

Known limitations

• The debug_bundler_* admin methods are reachable from the internet. Do not call the clear* or set* methods unless you mean to affect everyone.
• ethrex_submitPrivilegedFrameTransaction is unauthenticated on this devnet.
• The explorer history is in memory only and is cleared on restart.