CAPX

Capital markets, onchain. CAPX is a non-custodial interface to B20 tokenized equities on Base — thirteen public companies issued as native B20 tokens, marked continuously by Chainlink total-return feeds.

Everything on the site is a live read against Base mainnet. There is no seed data, no mock feed and no placeholder chart.

What is actually live

Surface	Source
Prices	Chainlink total-return feeds on Base (latestRoundData)
Charts	Real Chainlink round history walked back through getRoundData — every point is an onchain print
Supply & onchain value	B20 totalSupply × multiplier, valued at the live mark
Multiplier	B20 multiplier(), WAD-scaled, applied wherever a share count is shown
Token artwork	Decoded from the B20 contractURI (ERC-7572)
Portfolio	scaledBalanceOf per asset + USDC + ETH for the connected (or watched) wallet
Trade quotes	Uniswap v3 QuoterV2 simulated on Base — a real executable price, or an honest "no liquidity"
Swaps	Calldata built server-side against the live route, signed and sent by the user's own wallet
Quick buy	Pick a USDC size and a company on the landing page; hands ?side=&amount= to the asset page

Liquidity: routing, not a single pool

Nine of the thirteen assets have no minted supply on Base, so there is no secondary market to route through — the UI marks them Mint only and points at issuer mint/redeem. The four with supply (AAPL, GOOGL, META, NVDA) trade today at roughly the oracle mark.

Liquidity does not live where a naive integration would look. It sits mostly on Aerodrome concentrated-liquidity pools, with some routes crossing Uniswap v4 and PancakeSwap v3. Uniswap v3 — the obvious first place to check — holds either nothing or dust: GOOGLc has a v3 pool that will quote an executable fill about 98% away from the mark. Reading one venue produces confidently wrong answers, so CAPX aggregates and then checks the result against Chainlink:

Distance from oracle mark	Behaviour
under 1%	trades normally
1–5%	trades, warning shown
5–15%	blocked behind an explicit acknowledgement
over 15%	refused; issuer mint/redeem only

Both /api/quote and /api/swap grade independently, so a stale render cannot push an unsafe order through.

Fallback. If the aggregator is unreachable, both endpoints quote and build directly against the deepest Aerodrome Slipstream pool (factory 0xf8f2eB49…, quoter 0x514c8B5f…, router 0x698Cb2b6…, pools keyed by tick spacing rather than fee). The fill is real and executable, just single-hop rather than split — the UI says so rather than passing it off as the same quote.

Run it

npm install && npm run dev

Opens on http://localhost:3000. No API keys required — it defaults to the public Base RPC. Copy .env.example to .env.local and set a dedicated RPC before deploying; the public endpoint is rate-limited.

Routes

• / — landing page, live tickers, quick buy and onchain totals
• /markets — all thirteen assets, sortable, searchable, live sparklines
• /markets/[ticker] — chart over onchain rounds, contract references, trade panel
• /portfolio — connected wallet, or ?address=0x… to watch any wallet read-only
• /how-it-works — the B20 mechanics CAPX depends on, with links to verify each claim

API

All routes return live data and are safe to call directly.

• GET /api/markets — every asset with price, change, supply, TVL and round history
• GET /api/quote?symbol=NVDA&side=buy&amount=100 — aggregated executable fill, graded against the oracle
• GET /api/venues — which assets are routable right now, on which venues, at what spread
• POST /api/swap — calldata for the user's wallet to sign
• GET /api/portfolio?address=0x… — positions valued at the live mark
• GET /api/token?symbol=NVDA — decoded B20 contract metadata

Wallets

Coinbase Wallet, MetaMask and Phantom. Coinbase runs through its own SDK so it also covers Smart Wallet with nothing installed; MetaMask and Phantom connect via their injected providers and are probed before being offered — an undetected wallet shows an install link instead of a dead button. Brand marks are inline SVG, so they need no network request.

A note on the "Built on" strip

Base, Chainlink, Coinbase, USDC, Uniswap and OP Stack appear on the landing page with the role each one plays in the architecture. They are dependencies, not partners or sponsors — there are no commercial relationships behind any of those names.

Mobile

Built to be used on a phone, not merely to survive one. Tables become card lists below md so nothing scrolls sideways, a fixed bottom tab bar replaces the hamburger, viewport-fit=cover plus env(safe-area-inset-*) handles the notch and home indicator, and the chart shortens on small screens. Pinch zoom is deliberately left enabled for accessibility.

Light is the default theme; dark is opt-in and remembered in localStorage.

Design

Typography stands in for Ondo's licensed stack with open equivalents: Outfit (display), Figtree (UI), Newsreader (editorial serif), JetBrains Mono (tabular market data). Motion is motion/react, and every reveal has a timer failsafe so content can never be left invisible by an animation that did not run.

Caching

Round history costs ~1,500 eth_calls per full refresh, so it is cached separately from prices with a 90s TTL and stale-while-revalidate. Prices refresh on a 6s TTL behind a single in-flight request; browsers poll every 10s. Cold fetch is ~7s, warm responses are sub-20ms.

Scope

CAPX is not a broker-dealer, exchange, or investment adviser, and nothing it displays is investment advice. Tokenized equities are not available to US persons. One B20 token is not permanently one share — redemption applies the current onchain multiplier. Mint and redeem are performed by the issuer under KYC; secondary transfers are permissionless subject to onchain policy.

Reference: Tokenized stocks on Base · B20 specification