Routheus — Multichain DEX Router API

Q: Do I need an API key or account?

No. There is no signup, no API key and no subscription. Use the free tier directly, or pay per call in USDC via the x402 protocol for paid products.

Q: How do I pay for API calls?

Paid endpoints use the x402 protocol: you receive an HTTP 402 with a payment offer, sign a gasless USDC authorization off-line, and retry. Any x402 client (x402-fetch, Coinbase AgentKit) does this automatically. You are only charged for successful responses.

Live DEX token prices and best-route swap quotes, executable routes with prepared calldata (Permit2 supported), simulation-verified outputs, token metadata, token search and pool data across 13+ EVM chains. Pay per call in USDC via x402 — no API key, no subscription, no signup.

x402 v1 + v2 · exact · USDC pay on: Base · Polygon · Arbitrum · Avalanche · Solana 13+ EVM chains free tier — quotes & calldata, no key only successful responses are charged own pool-state engine — not an aggregator proxy

Free tier — try before you pay

Single-input quotes (4/min per IP) and quotes with calldata (2/min per IP) are free — no payment, no key. Free responses give the output amount, gas and the executable transaction (so you can execute the swap); full route info (pool addresses, per-leg amounts) and simulation available in the paid quote. Pay per call via x402 for full data, simulation-verified quotes, chained-arb, batches and higher limits.

Try it — one curl, no account

curl "https://routheus.xyz/base/api/router/quote?token_in=0x4200000000000000000000000000000000000006&token_out=0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913&amount_in=1000000000000000000"

On the free tier that returns a trimmed quote instantly. Past the free limit (or for paid products) you get an HTTP 402 with everything needed to pay: price, USDC contract, receiving address. Any x402 client (@x402/fetch, x402-axios, x402-reqwest, Coinbase AgentKit, MCP) signs the payment offline and retries automatically — settlement lands on-chain in ~1–2s and the receipt (tx hash) is returned in the X-PAYMENT-RESPONSE header.

Products & pricing

Product	Endpoint (GET)	Price	What you get
quote	`/{chain}/api/router/quote`	0.005 USDCper input amount · free tier: single-input	Best-route swap quote: output amount and split routing across venues, from our own pool-state engine.
quote_calldata	`/{chain}/api/router/quote?to=…`	0.01 USDCper input amount · free tier: single-input	Ready-to-sign swap transaction: route plus executable calldata (Permit2 supported) and min-out at slippage.
quote_sim	`/{chain}/api/router/quote?…&simulate=true`	0.02 USDCper simulated amount	Simulation-verified quote — amount_out IS the on-chain eth_call result, not an estimate. Failed sims are free.
quote_arb	`/{chain}/api/router/quote?…&quote_on_top_of_amounts=…`	0.03 USDCper request	Exclusive chained-state quoting for arbitrage sizing and MEV bundles — quotes as if prior in-flight swaps executed.
token_metadata	`/{chain}/api/tokens/metadata?token=…`	0.003 USDCper request	ERC-20 name, symbol, decimals, balance storage slot. Cache-only; unknown tokens return an error (never charged).
token_search	`/{chain}/api/tokens/search?query=…`	0.003 USDCper request	Search tokens by symbol, name or address — resolve a ticker to the right contract; returns pool counts.

Response examples

Every product returns a clean, stable public JSON schema. Expand a product to see its request parameters and a representative paid response (values illustrative). These same examples are in /x402/info (products[].response_example) and /openapi.json.

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Supported chains

ethereumbasearbitrumbscoptimismpolygonavalancheunichainsonicgnosishyperevmberachainhemi

Executing a swap route

Routes bought with to=<your address> include a ready-to-send transaction (tx: {to, data, value, chainId}). Before sending it, the input token needs an allowance — two options:

Option A — direct approve

ERC-20 approve(router, amount) to the router address in tx.to, then send tx as-is. Simple; one approval per token+amount.

Option B — Permit2 (recommended)

One-time ERC-20 approve(Permit2, ∞) to the canonical Permit2 (0x…22D473030F116dDEE9F6B43aC78BA3). Then request with_permit2_data=true: the response adds tx_permit2 — calldata with zeroed placeholders plus byte offsets (nonce_offset, permit_deadline_offset, signature_offset). Sign the EIP-712 PermitTransferFrom (domain: name "Permit2", your chainId, verifying contract Permit2; spender = router), splice nonce, deadline and 65-byte signature at those offsets, send. No per-swap approvals.

How payment works

Call a paid endpoint → HTTP 402 with an accepts array (price, asset, receiver).
Your client signs an EIP-3009 USDC authorization offline — gasless for you, the facilitator pays gas.
Retry with the X-PAYMENT header → payment is verified, your request runs.
Only useful answers settle: upstream errors and {"ok": false} results are never charged (X-Payment-Charged: false) and your authorization stays reusable.

One payment authorization pays for exactly one served response. Multi-input batches (amounts_in, up to 50 amounts) are priced per amount with a 10% batch discount. With simulate=true the returned amount_out is the on-chain simulated result — what you'd actually receive, not a local estimate; failed simulations are free. The exclusive quote_on_top_of_amounts product quotes on top of in-transit swaps (pool state mutated per prior amount) — built for arbitrage sizing, MEV bundles and multi-step strategies.

Machine-readable

/x402/info — full service + pricing JSON
/openapi.json — OpenAPI 3.1 with x-payment-info
/.well-known/x402 — x402 resource list
/llms.txt — plain-text summary for agents
/chain-peers — live chain list
/mcp — MCP server (free discovery tools for AI agents)

FAQ

What is Routheus?

Routheus is a multichain DEX router API. It returns best-route swap quotes, executable swap calldata (Permit2), on-chain simulation-verified outputs, and token/pool data across 13+ EVM chains — from its own real-time pool-state engine, not an aggregator proxy.

Is there a free tier?

Yes. Single-input swap quotes and quote-with-calldata are free, rate-limited per IP, with no payment or API key. Free responses include the output amount, gas, route shape and the executable transaction. Full route detail and on-chain simulation are on the paid call.

Do I need an API key or account?

No signup, no API key, no subscription. Use the free tier directly, or pay per call in USDC via the x402 protocol for paid products.

Which blockchains does Routheus support?

13+ EVM chains including Ethereum, Base, Arbitrum, BSC, Optimism, Polygon, Avalanche and more. See /chain-peers for the live list.

How do I pay for API calls?

Paid endpoints use the x402 protocol: you get an HTTP 402 with a payment offer, sign a gasless USDC authorization off-line, and retry. Any x402 client (x402-fetch, Coinbase AgentKit) does this automatically. You are only charged for successful responses.

How much does a swap quote cost?

Single-input quotes are free (rate-limited). Paid pricing per call in USDC: swap quote 0.005, quote + calldata 0.01, simulation-verified quote 0.02, chained arbitrage quote 0.03, token metadata and search 0.003 each. Live pricing at /x402/info.

Contact & custom plans

Start free — no signup. Need higher rate limits, a custom/enterprise plan, volume pricing, or a private deployment? Email [email protected] and we'll tailor limits and pricing to your integration.

Payments settle on-chain directly to the operator wallet via the x402 protocol. No funds are held by this service or its facilitator. Prices may change; the 402 response is always authoritative. Contact: [email protected].