# HALOWERK marktwerk Slippage Simulator

> HALOWERK marktwerk Slippage Simulator is a paid API for AI agents from markt.halowerk.com, paid per call via x402, $0.004/call, status unknown (last checked 2026-10-12).

Simulates order fill against live visible order books on Binance, Coinbase, Kraken, OKX, or Bybit, returning average fill price, worst price, and slippage metrics for a given side and size.

## Facts

- Endpoint: POST https://markt.halowerk.com/slippage?utm_source=zero.xyz
- Price: $0.004/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/halowerk-marktwerk-slippage-simulator-3317fb95
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_dM1YiHzNwW60D1pTQQisx

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 halowerk-marktwerk-slippage-simulator-3317fb95 -d '<json body>'
```

Example prompt: Simulate buying 50 ETH on Binance using the visible order book — tell me the average fill price, worst price touched, and slippage against mid, including taker fees.

## When to prefer this

Use this endpoint when you need pre-trade market impact and slippage estimation against real live order book depth on a specific centralized exchange. Prefer it over ticker-based mid-price estimates when order size is large enough to walk multiple book levels. It is especially valuable for execution routing decisions, OTC pricing benchmarks, or risk checks before placing large market or aggressive limit orders. Choose it over the multi-venue slippage walker when you want detailed single-venue fill analytics including fee-adjusted prices.

## Known failure modes

- Invalid or unsupported symbol format returns a validation error
- Requested venue not among supported five exchanges returns error
- Size of zero or negative number rejected by schema validation
- Symbol not listed on the requested exchange may return empty book or error
- Partial fill scenario: insufficient_liquidity=true with filled_pct < 100 and max_fillable_size returned — call is still valid and charged
- Network or exchange connectivity issues may delay or fail book retrieval

## How this service works

Takes side, size and size_unit and simulates the fill against the visible book of Binance, Coinbase, Kraken, OKX or Bybit. avg_price is the size weighted fill price, worst_price the last level touched, slippage is stated against the mid and against the best price on the executing side, with the reference named. If the visible depth is not enough the answer is still valid and paid: insufficient_liquidity is true, filled_pct says how far it got and max_fillable_size names the size the book actuall

## Output

Returns avg_price (size-weighted average fill price), worst_price (last order book level touched), slippage measured against both the mid price and the best price on the executing side with the reference named, and if depth is insufficient: insufficient_liquidity=true, filled_pct (how much of the order was filled), and max_fillable_size (maximum fillable quantity from visible book). Optionally includes taker fee layer on top of fill price.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "side": {
   "enum": [
    "buy",
    "sell"
   ],
   "type": "string",
   "description": "buy consumes the ask side, sell the bid side."
  },
  "size": {
   "type": "number",
   "description": "Order size, in the unit given by size_unit.",
   "exclusiveMinimum": 0
  },
  "venue": {
   "enum": [
    "binance",
    "coinbase",
    "kraken",
    "okx",
    "bybit"
   ],
   "type": "string",
   "default": "binance",
   "description": "Exchange whose book is used."
  },
  "symbol": {
   "type": "string",
   "pattern": "^[A-Za-z0-9]{2,15}/[A-Za-z0-9]{2,15}$",
   "description": "Trading pair as BASE/QUOTE, for example ETH/USDC."
  },
  "size_unit": {
   "enum": [
    "base",
    "quote"
   ],
   "type": "string",
   "default": "base",
   "description": "base means size is in BASE, quote means size is in QUOTE."
  },
  "include_fees": {
   "type": "boolean",
   "default": false,
   "description": "Adds the taker fee of the entry tier on top of the fill price."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/halowerk-marktwerk-slippage-simulator-3317fb95/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from markt.halowerk.com](https://www.zero.xyz/host/markt.halowerk.com/llms.txt)