Robinhood Chain has no public mempool

Robinhood Chain has no public mempool. A transaction goes from the sender to the sequencer, and the sequencer orders it on arrival. The public RPC does not show the transaction before that. The earliest public view of a transaction is the sequencer feed. This page shows what each public interface gives you, and how to measure the gap from your own host.

The sequencer orders on arrival and keeps its queue inside

The Robinhood Chain docs state the ordering rule: "Robinhood Chain utilizes a first-come, first-served sequencing model, where the order is determined strictly by the arrival time at the sequencer." [1]

The docs also state that a fee does not buy a place: "Priority gas auctions do not exist here; consequently, increasing your fee will not shift your transaction ahead of others already in the queue." [2]

Robinhood Chain runs on Arbitrum. The Arbitrum docs describe where a new transaction waits: "Admitted transactions land in an unordered waiting list, the first stage of the Sequencer's two-stage mempool." Under first-come, first-served ordering, "arrival time sets the order." [3]

In its section on priority gas auctions, the same page says: "The mempool stays private." [3] No public endpoint lets you read the list.

What the RPC shows for pending transactions, and when

We tested the public RPC, https://rpc.mainnet.chain.robinhood.com, on 2026-10-25 at 22:55 UTC and again on 2026-10-26 at 13:33 UTC. On 2026-10-25 it reported the client version nitro/v3.12.1-rc.2. [4]

• eth_newPendingTransactionFilter returned error -32601: "the method eth_newPendingTransactionFilter does not exist/is not available". [4]
• txpool_content and txpool_status returned the same error. [4]
• eth_getBlockByNumber("pending") returned the same block hash as eth_getBlockByNumber("latest") on 2026-10-25, and the same sealed block in one batch request on 2026-10-26. The tag returns a sealed block, not a pending one. [4]

So the public RPC shows a transaction only after the sequencer has put it in a block and the node has executed that block. The docs describe that moment as the soft confirmation: "The sequencer accepts, orders, and executes your transaction and returns a receipt." [5]

The docs also say that the public endpoints "are rate-limited and not recommended for production use." [6] We tested only the public RPC. Ask your RPC provider what its own node returns.

The earliest public view is the sequencer feed

The sequencer publishes each block on its feed. The Arbitrum docs describe the step: the Broadcaster "pushes it to subscribers over the real-time feed. This is the moment users get soft finality." [3] The standard feed "publishes complete blocks and is free to consume." [7]

The public Robinhood Chain feed is wss://feed.mainnet.chain.robinhood.com. [6] A Nitro node reads it with one flag: "To subscribe to the sequencer feed for low-latency updates, add --node.feed.input.url to your start command." [8]

Each feed message is a Nitro broadcast message in JSON. One entry is one L2 block. An entry holds: [9]

• sequenceNumber: the position of the message in the sequencer's stream.
• message.message.header: the L1 message header, with the kind, the L1 block number and the timestamp.
• message.message.l2Msg: the L2 message in base64. For kind 3, it holds the signed transactions of the block.
• blockHash and signatureV2: the block hash that the sequencer claims, and the sequencer's signature over the entry.

A feed entry is not a pending transaction. It is a block that the sequencer has already ordered. It is the first public record of that order. The feed page gives the full message format.

Raw signed transactions as the sequencer emits them

The FirstLight /tx stream "sends each signed Robinhood Chain transaction as one binary record, as soon as its bytes complete, usually before its block completes." [10]

The payload of each record is "the exact signed transaction bytes". The keccak-256 hash of these bytes is the transaction hash. [10] A record that comes before its block completes has the provisional flag. One EntryComplete record then confirms the block, with its transaction count and block hash. [10]

/tx does not show a transaction before the sequencer orders it. No public interface does. The raw transactions page gives the record format. /tx is part of the Ultra plan.

Measure the gap yourself with the free /headers stream

The /headers stream is free. It sends up to three records for each block: a Lead as the block starts, a Footer as it completes, and a Header with the L1 message header of the block. [11] A Lead "arrives at about the time of the block's first raw transaction" on /tx. A Footer arrives "within about 0.1 ms of the complete block on the feed." [11]

To measure the gap from your own host: [12]

1. Get a free key (see the Free plan).
2. Connect to /headers and to the feed or RPC subscription that you use today, from the same host.
3. Stamp each arrival with one clock.
4. Match the blocks by block hash.
5. Subtract the two stamps for each block. Compare the quantiles, not only the mean.

A newHeads subscription is a useful second comparator. A node publishes it "after the block has executed". [12] The measurement page gives the full method.

FAQ

Sources

All pages fetched on 2026-10-25.

1. Robinhood Chain docs, overview, "Predictable Transaction Ordering": docs.robinhood.com/chain/ (fetched 2026-10-25)
2. Robinhood Chain docs, "Differences from Ethereum": docs.robinhood.com/chain/differences-from-ethereum (fetched 2026-10-25)
3. Arbitrum docs, "The Sequencer and censorship resistance", sections "1. Receipt and admission", "4. Persistence and broadcast" and "The two-stage mempool": docs.arbitrum.io/how-arbitrum-works/sequencer (fetched 2026-10-25)
4. FirstLight measurement: JSON-RPC calls to rpc.mainnet.chain.robinhood.com at 2026-10-25 22:55:40 UTC: eth_newPendingTransactionFilter, txpool_content, txpool_status, eth_getBlockByNumber with pending and latest (both returned hash 0xe832bc91c5abdec0a5a2f520e472fe2b76aa9a6040bec6e0b65d4a555a97d3ef), web3_clientVersion. Re-checked on 2026-10-26 between 13:25 and 13:33 UTC: eth_newPendingTransactionFilter, txpool_content and txpool_status each returned error -32601 ("the method ... does not exist/is not available"); in one batch request, eth_getBlockByNumber with pending and latest returned the same sealed block, in three requests at 13:28 UTC and three at 13:33 UTC.
5. Robinhood Chain docs, "Transaction Finality", "Soft confirmation": docs.robinhood.com/chain/transaction-finality (fetched 2026-10-25)
6. Robinhood Chain docs, "Connecting", "Public Endpoints": docs.robinhood.com/chain/connecting (fetched 2026-10-25)
7. Arbitrum docs, "How to read the sequencer feed": docs.arbitrum.io/run-arbitrum-node/sequencer/read-sequencer-feed (fetched 2026-10-25)
8. Robinhood Chain docs, "Run a full node": docs.robinhood.com/chain/run-a-full-node (fetched 2026-10-25)
9. FirstLight docs, "The Robinhood Chain sequencer feed", section "Messages": first-light.stream/docs/feed (fetched 2026-10-25)
10. FirstLight docs, "Raw transactions on /tx": first-light.stream/docs/transactions (fetched 2026-10-25)
11. FirstLight docs, "Block headers on /headers", section "Timing": first-light.stream/docs/headers (fetched 2026-10-25)
12. FirstLight docs, "How FirstLight measures feed latency", sections "Comparators" and "Measure it yourself": first-light.stream/docs/measurement (fetched 2026-10-25)
13. CoinDesk, Ian Allison, "Robinhood Chain considers technology that gives paying traders priority", 2026-10-09 14:11 EDT: www.coindesk.com/business/2026/10/09/robinhood-chain-considers-technology-that-gives-paying-traders-priority (fetched 2026-10-25)