Inside the Nexus API: Market Data, Wallet Analytics, Transactions, and Streaming on One Platform
Inside the Nexus API: Every Capability on One Platform
Most Cardano data providers answer one question: "what happened on chain?" Real products need more, what a token is worth, what a wallet has earned, how to construct the next transaction, and what is happening right now. Nexus answers all of them through a single API, over plain REST with an OpenAPI 3.1 spec, so the whole protocol is HTTPS plus an X-Api-Key header.
This post is the map of what that key unlocks.
The platform in one paragraph
Nexus is a managed, full-stack data and transaction API for UTXO chains. Cardano is live today; Bitcoin and Midnight are on the roadmap and served by the same API when they arrive. Every request fans out across multiple providers, Yaci, Koios, Blockfrost, and Nexus's own indexers, with per-provider health checks routing around degraded upstreams, and hot data served from cache. You integrate once and inherit the redundancy.
Market Data: prices, candles, pools, and order books
The Market Data add-on aggregates all 11 Cardano DEXes (Minswap V1/V2, SundaeSwap V1/V3, WingRiders V1/V2, VyFi, Splash, TeddySwap, MuesliSwap, CSwap) into one surface: current and historical token prices, OHLCV candles (15m, 1h, 1D, 1W), an RSI(14) technical indicator, pool TVL and reserves, real and AMM-simulated order books, recent swaps, top-trader rankings, and NFT collection stats including floor prices and sales from jpg.store.
Wallet Analytics: holdings, history, and FIFO P&L
Point the API at any Cardano stake address and get current holdings with USD valuation, wallet value over time, and realized plus unrealized profit-and-loss computed on a FIFO cost basis, single wallet or multi-wallet in one request. This is the layer portfolio trackers, tax tooling, and reporting products otherwise have to build themselves.
Transaction Builder: intent in, unsigned CBOR out
Send intent, recipient and amount, a delegation, a governance vote, and Nexus returns an unsigned transaction CBOR with UTXO selection, fee calculation, and change outputs handled server-side. You sign client-side and submit; private keys never touch Nexus servers. Builders cover transfers, stake delegation, stake key registration, DRep registration, vote delegation, and reward withdrawal.
DEX Aggregator: best-route swaps as an API
The Nexus DEX aggregator turns a token swap into four REST calls: list the swappable tokens, quote the best route across Cardano's DEXes, build the unsigned swap transaction, and submit the signed result. Routing, price impact, and CBOR construction happen server-side; signing stays entirely with your users. It ships as part of the Transaction Builder add-on, so a full swap feature for your wallet, bot, or dApp goes live without a single line of DEX-specific integration code.
WebSocket Streaming: live data without polling
A SockJS + STOMP endpoint streams live token prices, executed DEX swaps, and dApp events. Subscribe to a topic and receive a snapshot plus updates instead of polling on a loop. Scale and Enterprise plans include streaming; Starter, Pro, and Unlimited packages add it to any plan.
MCP Server: your AI agents, connected to the chain
Nexus hosts a Model Context Protocol endpoint that turns the platform into native tools for Claude, Cursor, and any MCP-compatible agent, 25 tools across Cardano, Bitcoin, Midnight, market data, transaction building, and account management, authenticated with the same API key.
Pricing that reads like a menu, not a formula
Every plan is a flat monthly price with a request pool. A request is a request: no compute-unit weighting, no per-method credit taxes, no surprise bills at month end.
Base tiers
Tier | Price | Requests / month | Highlights |
|---|---|---|---|
Builder | $29/mo | 2,000,000 | 7-day trial, 3 API keys |
Growth | $79/mo | 10,000,000 | 5 API keys |
Scale | $199/mo | 50,000,000 | 10 API keys, priority support, streaming included |
Enterprise | $499/mo | 200,000,000 | Unlimited API keys, every add-on bundled, WS Unlimited included |
Dedicated | from $2,000/mo | negotiated | Isolated infrastructure, contractual SLA, dedicated support channel |
Add-ons
Pick only what you need; REST add-ons share your tier's request pool, so there is one number to track.
Add-on | Price | What it adds |
|---|---|---|
Market Data | +$19/mo | Prices, candles, pools, order books, and NFT sales across all 11 Cardano DEXes |
Wallet Analytics | +$15/mo | Holdings, value history, and FIFO P&L per stake address |
Transaction Builder | +$19/mo | Server-side transaction building, including the DEX aggregator swap flow |
MCP Server | +$19/mo | Hosted MCP endpoint for Claude, Cursor, and other AI agents |
IPFS | +$5/mo | Gateway fetch, content inspection, IPNS, and per-key pinning |
WebSocket streaming
Included with Scale and Enterprise. On Builder and Growth, add a package:
Package | Price | Concurrent connections | Messages / month |
|---|---|---|---|
WS Starter | $29/mo | 2 | 100,000 |
WS Pro | $59/mo | 10 | 2,000,000 |
WS Unlimited | $99/mo | Unlimited | Unlimited |
On top of all of it, holding $GERO unlocks a sliding subscription discount of up to 20%.
Start building
The 7-day Builder trial exposes the full surface, so you can validate data quality and latency against your own workload before committing budget. Get your API key at nexus.gerowallet.io, or explore every endpoint with the live playground at nexus.gerowallet.io/docs. For Enterprise and Dedicated plans, reach out via the Nexus support page.