# x402-solvers Arbitrage Cycle Probe

> x402-solvers Arbitrage Cycle Probe is a paid API for AI agents from x402-solvers.onrender.com, paid per call via x402, $0.001/call, status unknown (last checked 2026-10-20).

Scans a directed token swap-rate graph for negative-weight cycles (arbitrage opportunities), returning a boolean signal and magnitude estimate without revealing the path.

## Facts

- Endpoint: POST https://x402-solvers.onrender.com/v1/cycles/probe?utm_source=zero.xyz
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-20
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/x402-solvers-arbitrage-cycle-probe-931b9246
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_2IJ_LloYJxCyhRYY6fsVu

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability x402-solvers-arbitrage-cycle-probe-931b9246 -d '<json body>'
```

Example prompt: Check these token swap rates across my pools for an arbitrage opportunity — edges: ETH→USDC at 2000 (0.3% fee on Uniswap pool 0xABC), USDC→DAI at 1.001 (0.05% fee), DAI→ETH at 0.0005005 (0.3% fee) — just tell me if a profitable cycle exists and how large it is.

## When to prefer this

Choose this endpoint as a cheap, fast pre-filter before running expensive full arbitrage path-finding algorithms. It is ideal for high-frequency trading agents that need a boolean signal and rough magnitude to decide whether to invoke a heavier solver. Prefer it over full cycle-enumeration endpoints when you don't need the actual path — only the existence and scale of the opportunity. Best suited for agents that supply their own observed rates (the server makes no RPC calls).

## Known failure modes

- Missing required fields (from, to, rate) on any edge returns a validation error
- Rate value of 0 or negative is rejected (exclusiveMinimum: 0)
- Fee value ≥ 1 is rejected (exclusiveMaximum: 1)
- Empty edges array (minItems: 1 violated) returns 400
- Payment not included or insufficient USDC results in 402 Payment Required
- Malformed JSON body returns parsing error
- Timeout if graph is extremely large

## How this service works

Detect whether an arbitrage opportunity exists in a set of token exchange rates (multi-pool negative-cycle scan). Cheap boolean + magnitude signal for trading agents. POST a swap-rate graph, get back whether a profitable cycle exists and how large — without the path.

## Output

Returns a boolean indicating whether a profitable arbitrage cycle exists in the submitted swap-rate graph, along with a magnitude signal quantifying the size of the opportunity — without revealing the specific cycle path.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "edges": {
   "type": "array",
   "items": {
    "type": "object",
    "required": [
     "from",
     "to",
     "rate"
    ],
    "properties": {
     "to": {
      "type": "string",
      "description": "Destination token symbol."
     },
     "dex": {
      "type": "string",
      "description": "Venue label; echoed back untouched."
     },
     "fee": {
      "type": "number",
      "minimum": 0,
      "description": "Fractional swap fee, e.g. 0.003 for 0.30%. Defaults to 0.",
      "exclusiveMaximum": 1
     },
     "from": {
      "type": "string",
      "description": "Source token symbol."
     },
     "pool": {
      "type": "string",
      "description": "Pool address; echoed back untouched."
     },
     "rate": {
      "type": "number",
      "description": "Units of `to` per 1 unit of `from`, BEFORE fees.",
      "exclusiveMinimum": 0
     }
    }
   },
   "minItems": 1,
   "description": "Directed exchange-rate edges describing a token swap graph. Supply the rates you observed; the server makes no RPC calls of its own."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/x402-solvers-arbitrage-cycle-probe-931b9246/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402-solvers.onrender.com](https://www.zero.xyz/host/x402-solvers.onrender.com/llms.txt)