The first Robinhood Chain app you should build is not another token

I built a @RobinhoodApp Chain fully functioning demo app around a stock index basket for a reason. Deploying Solidity with Foundry, reading with viem, and writing with wagmi is the path you already know.

What you feel as a builder is what happens when the ERC-20s you’re composing with represent market assets.

The chain is custom, but your first deploy is familiar

Robinhood Chain is a custom @Arbitrum Chain built on the Arbitrum stack. It uses Ethereum blobs for data availability and ETH as the gas token.

For you, the first deploy feels like any other EVM deploy. Point Foundry at https://rpc.testnet.chain.robinhood.com, use your private key, broadcast the contract, and you’re live.

Robinhood gets a dedicated chain with custom block production, pricing, infrastructure, and product controls. Builders still get the Ethereum contract model and tooling. Robinhood Chain runs on Arbitrum Nitro, the same technology as Arbitrum One, deployed as its own chain.

State roots settle to Ethereum with fraud proofs. Gas is paid in ETH. ERC-4337 and EIP-7702 account abstraction are live at canonical addresses. Stylus lets Solidity contracts call Rust contracts.

You don’t need to rebuild any of that first.

Start with the asset layer.

Stock Tokens change the assumptions around ERC-20s

Stock Tokens are ERC-20s. You can read balances, transfer, approve, and compose them the way you would with other tokens.

But they’re ERC-20s with one extra accounting layer.

Stock Tokens implement ERC-8056, the Scaled UI Amount extension. Raw balances don’t rebase when a split or dividend adjustment changes the economic relationship between one token and the underlying equity. Instead, the token exposes uiMultiplier.

What does that buy you in a contract?

Your contract can keep accounting in stable raw units while wallets and UIs show share-equivalent amounts. If a split changes the multiplier, your app doesn’t suddenly have its internal balances mutated underneath it.

The display conversion is straightforward: raw balance multiplied by uiMultiplier, divided by 1e18.

Your UI should show balanceOfUI or apply that multiplier itself. Your contracts should treat raw token balances and displayed share-equivalent balances as different values that can diverge.

The ERC-20 interface still works. The market asset context travels with it, and you account for both.

The app is small so the boundaries stay visible

The demo app is an index basket. A user deposits Stock Tokens, receives an ERC-20 basket share, sees that share priced from Chainlink feeds, and can redeem back into the underlying components.

You can run it locally, deploy it to Robinhood Chain testnet, fork-test the mainnet configuration, and inspect the live walkthrough at https://robinhood-chain-dapp.vercel.app/ with source at https://github.com/hummusonrails/robinhood-chain-dapp-example.

There are two contracts.

BasketFactory deploys and records baskets. It is permissionless and does not custody anything.

BasketToken holds components, mints shares, redeems shares, and prices shares. It has no owner and no upgrade path.

Each basket stores a fixed list of components. A component is a token, a feed, and the raw amount of that token backing one basket share.

The mainnet demo basket uses TSLA, NVDA, and AAPL Stock Tokens with their Chainlink feeds. One TRIO share is backed by 0.4 TSLA, 0.3 NVDA, and 0.3 AAPL.

On testnet, the demo uses real faucet Stock Tokens for TSLA, AMZN, and NFLX with mock Chainlink feeds. That split exists because the testnet gives you Stock Tokens to build with, while the production Stock Token feeds live on mainnet.

The walkthrough prices one share live in the browser from the same Chainlink reads the contract uses: multiply each feed by the units backing a share, then sum.

That design is intentionally plain. You can see the line between ownership, pricing, and settlement without a pile of app-specific glue.

Pricing tells you value. Redemption gives you assets.

Minting follows the ERC-20 path you already know.

The frontend approves each component token, then calls mint on the basket. Onchain, the basket pulls the required component amounts and mints shares in the same transaction.

The rounding direction matters. Mint rounds up so a minter cannot underpay the basket reserves by dust.

Redeem is the mirror image. The basket burns first, transfers components out, and rounds down so reserves cannot be overdrawn.

Redeem skips the oracle path. No price check, no factory permission. The basket returns the tokens it holds.

That separation is the design decision I would copy into almost any Stock Token app. Pricing tells the UI what a share is worth. Redemption returns the tokens held by the contract.

In a lot of crypto apps, you wire price into the exit path because the token is the product. With a collateral basket, that becomes a fragility point. If the oracle is stale, market hours are closed, or a feed is temporarily unavailable, users should still be able to redeem the collateral the contract holds.

Stock feeds follow market hours. Corporate action multipliers can change. Feed prices already include the multiplier. These aren’t edge cases. They’re part of the asset surface.

The repo is built around the real development loop

The local deploy creates mock Stock Tokens, mock Chainlink feeds, the factory, and a demo Tech Trio basket. It also writes the frontend environment file so the app can read the deployed addresses.

For testnet, you get ETH and Stock Tokens from the Robinhood Chain faucet, then deploy with the same project.

One Foundry script handles local, testnet, and mainnet by switching on block.chainid. Chain ID 4663 uses the mainnet components. Chain ID 46630 uses the testnet components. Everything else uses the local mock setup.

The testnet deployment behind the live walkthrough is:

BasketFactory: 0xC1940D5fd58ce735A44a53f910852B12250F6a14

BasketToken TRIO: 0x7633e0920Ea46A8Ec54F61C95adECD391c01Edd4

Before mainnet, the repo runs fork tests against live Robinhood Chain mainnet state. The fork test creates the basket, gives a test account TSLA, NVDA, and AAPL balances inside the fork, mints 2 TRIO shares, checks that the basket holds 0.8 TSLA, redeems, and verifies total supply returns to zero.

That is the loop you want for this kind of app: mocks for speed, testnet for wallet flow, fork tests for live integration assumptions, mainnet only after the path is uneventful.

The testnet deploy behind the walkthrough was a real session: five contracts, priced in ETH, verified on Blockscout, for an estimated 0.000122 ETH in gas.

That price comes from how the Arbitrum stack orders and settles work. Transactions arrive first come, first served into roughly 250ms blocks, get batched, and post to Ethereum as blob data. Fees are L2 execution gas plus the L1 data fee.

Token Terminal data recently showed the median Robinhood Chain transaction fee around $0.00127 and trending down.

Read the Robinhood value statement as an engineering prompt

Johann Kerbrat, SVP and GM of Crypto at Robinhood, put it this way:

“Robinhood Chain lays the groundwork for an ecosystem that will define the future of tokenized real-world assets and enable builders to tap into DeFi liquidity within the Ethereum ecosystem.”

Read that as a product spec, not a slogan.

If equities, ETFs, feeds, and lending markets become normal onchain components, the app surface expands past “deploy another token.”

In DeFi, you care about composable ownership. In tokenized equities, you also care about corporate actions. In consumer finance, you care about what the user can redeem when price data is not the same thing as settlement.

On Robinhood Chain you can build products where ownership, pricing, collateral, and settlement are all programmable. You still have to design those boundaries carefully, because the asset surface doesn’t forgive loose coupling.

Start with the working system

The index basket demo here isn’t the only app to build on Robinhood Chain. It’s the right first one because it touches the surfaces your own app will probably need: Stock Token reads, approvals, transfers, ERC-8056 display logic, Chainlink Stock Token feeds, mint and redeem flows, local mocks, testnet deployment, Blockscout verification, mainnet fork tests, and a Next.js frontend using wagmi and viem.

Don’t treat this demo app as a permanent template. Steal the shape of the work: keep contracts small, separate pricing from settlement, treat real-world asset details as part of the protocol surface, and test the same assumptions from local mocks to live mainnet state.

Robinhood Chain gives you the familiar EVM path first. Solidity contracts. Foundry deploys. ERC-20 approvals. ETH gas.

Then it gives you the part worth learning: market assets you can compose with.

Start with the working app, break it locally, deploy it on testnet, fork the mainnet assumptions, and look carefully at where the basket refuses to depend on price. That’s the design decision the demo is teaching.

Explore the walkthrough at https://robinhood-chain-dapp.vercel.app/ and the source at https://github.com/hummusonrails/robinhood-chain-dapp-example.