Arb DEX

Live cross-DEX crypto prices read from on-chain pool state: per-venue price, liquidity depth and gross cross-venue spread across BSC, Polygon, Arbitrum, Base, Avalanche and Optimism. Works keyless, no account.

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arb-dex-mcp

Live cross-DEX crypto prices for your AI agent — per-venue pool price, pool liquidity and the gross cross-venue spread on 6 EVM chains, read straight from on-chain pool state.

Chains: BSC · Polygon · Arbitrum · Base · Avalanche · Optimism. Venues: PancakeSwap (v2 + v3), Uniswap v3, SushiSwap, QuickSwap, Biswap, ApeSwap, BaseSwap, Trader Joe, Pangolin — every v2-style pool and every v3 fee tier separately, because a $12k 1% pool and a $19M 0.01% pool are not the same quote.

Nothing is modelled, estimated or backfilled. Every payload states its own block number and carries its own scope note, so an agent that quotes a figure also has the caveats attached to it.

Works with no API key against a free hourly public snapshot. Docs · npm

Quickstart

Nothing to clone or build. Your MCP client fetches the package. Requires Node 18+.

Claude Desktop

claude_desktop_config.json — macOS ~/Library/Application Support/Claude/, Windows %APPDATA%\Claude\:

{
  "mcpServers": {
    "arb-dex": {
      "command": "npx",
      "args": ["-y", "arb-dex-mcp"],
      "env": {
        "RAPIDAPI_KEY": "your-rapidapi-key-here"
      }
    }
  }
}

Restart Claude Desktop; the six tools appear under the connectors icon. Drop the env block entirely to run keyless — the server still starts and the free-snapshot tools still answer.

Claude Code

claude mcp add arb-dex --env RAPIDAPI_KEY=your-rapidapi-key-here -- npx -y arb-dex-mcp

Keyless:

claude mcp add arb-dex -- npx -y arb-dex-mcp

Then /mcp to confirm it connected.

Cursor

~/.cursor/mcp.json (global) or .cursor/mcp.json (per project):

{
  "mcpServers": {
    "arb-dex": {
      "command": "npx",
      "args": ["-y", "arb-dex-mcp"],
      "env": {
        "RAPIDAPI_KEY": "your-rapidapi-key-here"
      }
    }
  }
}

Cursor → Settings → MCP shows the server and its tools once the file is saved.

Any other MCP client

Same three facts: command npx, args ["-y", "arb-dex-mcp"], transport stdio, optional env RAPIDAPI_KEY.

Try it

Real prompts, and the real shape that comes back. Payloads below were measured live on 2026-08-15; they are trimmed for width but nothing is invented.

1. "What is WBNB/USDT trading at on every BSC venue right now?"

get_prices reads every pool holding the pair — v2 pairs and each v3 fee tier separately — at one stated block:

{
  "pair": "WBNB/USDT",
  "network": "bsc",
  "chainId": 56,
  "blockNumber": 116151268,
  "pricesByVenue": [
    { "venue": "pancake",        "surface": "v2", "feeBps": 25,  "price": 611.7347, "tvlUsd": 56834814.36 },
    { "venue": "biswap",         "surface": "v2", "feeBps": 10,  "price": 610.8278, "tvlUsd": 415733.94 },
    { "venue": "apeswap",        "surface": "v2", "feeBps": 20,  "price": 611.1244, "tvlUsd": 3659.06 },
    { "venue": "pancakeV3:1",    "surface": "v3", "feeBps": 1,   "price": 610.5684, "tvlUsd": 18596810.32 },
    { "venue": "pancakeV3:5",    "surface": "v3", "feeBps": 5,   "price": 610.6531, "tvlUsd": 4941099.44 },
    { "venue": "pancakeV3:25",   "surface": "v3", "feeBps": 25,  "price": 610.6304, "tvlUsd": 52534.35 },
    { "venue": "pancakeV3:100",  "surface": "v3", "feeBps": 100, "price": 609.1025, "tvlUsd": 12206.21 }
  ],
  "bestBuy":  { "venue": "pancakeV3:100", "price": 609.1025 },
  "bestSell": { "venue": "pancake",       "price": 611.7347 },
  "midSpreadBps": 43.22,
  "crossDex": {
    "grossSpreadBps": 0,
    "grossUsd": 0,
    "optimalInput": { "amount": 0, "token": "WBNB", "usd": 0 },
    "buyVenue": "-",
    "sellVenue": "-"
  },
  "liquidity": { "venues": 7, "totalTvlUsd": 80856857.67 },
  "source": "rpc"
}

Read the two spread numbers against each other. The raw mid spread is 43 bps — and the gross capturable spread is 0. The 609.10 quote lives in a $12k pool; the size that would actually clear it moves the price past the gap before you get there. A tool that reported only the 43 bps would be handing an agent a number it cannot trade. This one reports both, and optimalInput is where the honesty lands.

2. "Show me the cross-DEX spreads on Base — are any actually capturable?"

get_spreads sweeps a whole chain and ranks by gross USD at the optimal size, not by headline basis points:

{
  "network": "base",
  "chainId": 8453,
  "scannedPairs": 11,
  "opportunities": [],
  "found": 0,
  "filters": { "minSpreadBps": 10, "minVenueTvlUsd": 1000, "minGrossUsd": 0.01, "limit": 5 },
  "ranking": "gross USD at the optimal trade size, NOT raw spread — a large spread with a tiny optimal size is not an opportunity",
  "scope": "GROSS cross-venue spread from live pool state, BEFORE gas, MEV and any slippage beyond the optimal size. Not a profit estimate and not trade advice. Venues below the liquidity floor are excluded because a spread against a dust pool is an artefact, not an opportunity.",
  "elapsedMs": 2847
}

found: 0 is a real answer and it is the common one. Eleven pairs scanned, nothing cleared the floor. Venues under $1,000 TVL are dropped outright. When rows do come back, each carries capturable, warning and shallowestSideTvlUsd so a big basis-point number cannot mislead on its own. This tool will tell your agent there is nothing there — which is the whole point of asking it.

3. "How much history does arb-dex actually have, and for which chains?"

get_history_summary sizes the archive before you query it:

{
  "rows": 133,
  "rowsWithPairDetail": 103,
  "rowsByEra": { "digest-totals-only": 30, "top-list-pairs": 5, "full-sweep": 98 },
  "pairsTracked": 107,
  "firstAt": "2026-08-10T17:35:09.355Z",
  "lastAt":  "2026-08-15T20:54:34.417Z",
  "spanHours": 123.32,
  "chainsSeen": ["arbitrum", "avalanche", "base", "bsc", "optimism", "polygon"],
  "pairs": [
    { "chain": "polygon",  "pair": "WBTC/USDC", "observations": 103, "qualifiedObservations": 39 },
    { "chain": "bsc",      "pair": "BTCB/USDT", "observations": 99,  "qualifiedObservations": 15 },
    { "chain": "arbitrum", "pair": "ARB/USDC",  "observations": 98,  "qualifiedObservations": 0 }
  ]
}

Coverage is only what was measured. A gap stays a gap — rowsByEra says how much detail each era of rows carries, and ARB/USDC having 98 observations but 0 qualified is the archive telling you that pair has never once cleared the spread floor.

Tools

Tool	What it answers	Access
`get_chains`	Which chains are covered, their chain IDs, tokens and DEX venues	Any key · keyless returns the chain list only, and says so
`get_pairs`	What is priceable on one chain: token universe, venues, pair syntax	Any key · keyless returns the measured subset, labelled as such
`get_prices`	One pair's price at every venue holding a pool for it, plus reserves, TVL, fee tier and the cross-DEX spread	Any key
`get_spreads`	A whole chain's cross-venue dislocations, ranked by gross USD at the optimal size	Any key for `live: true` · keyless serves the free hourly snapshot
`get_history_summary`	What the measurement archive covers: rows, pairs tracked, chains seen, span, retention	Any key (free tier included)
`get_history`	One pair's per-venue price/liquidity series and gross cross-venue spread over 24h / 7d / 30d	PRO plan — see Plans

The two history tools read the service's own measurement archive, so they answer the question the live tools cannot: whether a dislocation persisted or was a single sample. Sampling is roughly hourly, and gaps are never interpolated or backfilled. Call get_history_summary first to see what span exists before asking for a window.

What it will not do

Spreads are gross — before gas, MEV and slippage beyond the optimal size. Not a profit estimate and not trade advice.
It never fabricates a row. Without a key, get_chains, get_pairs and get_spreads answer from the free public surface and each carries a limitation field naming exactly what a key would add. get_prices, get_history_summary and get_history return an explicit key-required error with the signup link rather than a thinner answer dressed up as a full one.
It does not execute trades, hold funds, or touch a wallet. It is read-only market data.
This package ships no credentials of any kind. The key is yours and stays in your config.

Get a key

The paid tools call the API through RapidAPI using your own key.

Subscribe — there is a free tier: https://rapidapi.com/donnydev/api/multi-chain-dex-prices-liquidity
Copy your X-RapidAPI-Key from the RapidAPI dashboard.
Put it in RAPIDAPI_KEY in the config above — never in code, and never in a commit.

Plans

Five of the six tools work on the free tier. Only the per-pair history series is gated:

Plan	Adds
BASIC ($0)	Live quotes on every chain, plus `get_history_summary` so you can size the archive before you buy it
PRO ($15/mo)	`get_history` — the measured per-venue series for one pair, 24h window, 1000 calls/mo
ULTRA ($49/mo)	No window limit and no history meter, plus depth/slippage and spread alerts
MEGA ($149/mo)	Bulk paging over the complete archive for your own store

Calling get_history below PRO returns an explicit tier_required error naming the plan and the upgrade URL — it does not fail silently or return an empty series.

Configuration

Env var	Default	Purpose
`RAPIDAPI_KEY`	—	Your RapidAPI key. Required for the paid tools.
`ARB_DEX_TIMEOUT_MS`	`45000`	Request timeout. A live full-chain sweep is a real on-chain read and can take ~30s.
`ARB_DEX_FREE_BASE_URL`	production origin	Override the free-surface host.
`ARB_DEX_RAPIDAPI_HOST`	`multi-chain-dex-prices-liquidity.p.rapidapi.com`	Override the RapidAPI host.

Set these in your MCP client's env block (see the configs above). .env.example ships in the package and documents the same variables for local runs from a clone.

Test

The test suite is not in the npm tarball — run it from a clone:

git clone https://github.com/donnywin85/arb-dex-mcp.git
cd arb-dex-mcp && npm install

npm run selftest                    # keyless: exercises the free fallbacks
RAPIDAPI_KEY=... npm run selftest   # keyed: exercises the paid routes

The test spawns the server over stdio and calls every tool against the real production API — nothing is mocked. It asserts on live values (block number, per-venue prices, scanned-pair counts), so a run that passes is evidence the data path works end to end.

License

MIT — see LICENSE.