# How to build a Polymarket trading bot (50ms delay edition)

> Source: <https://dev.to/soulcrancerdev/how-to-build-a-polymarket-trading-bot-50ms-delay-edition-20o4>
> Published: 2026-08-17 23:12:57+00:00

*Polymarket just cut the taker delay from 250ms to 50ms*

**Here’s how to build a bot that actually works under the newest rules**

On August 17, 2026 at 11:00 AM UTC, Polymarket reduced the taker delay on crypto markets from 250ms to 50ms. Official announcement from @PolymarketDevs.

This is the latest in a series of changes:

The 50ms window is now live. Half the bots that were tuned for the previous buffer just got slower relative to the market. The opportunity for well-engineered makers (and the risk for slow ones) just increased.

If you ask an AI for a Polymarket bot today and it still talks about 500ms or even 250ms as the current state, throw that code away. It will lose money.

**Taker delay is now 50ms (Aug 17, 2026)**

Taker orders that cross the book wait only 50ms before execution (down from 250ms). There is almost no time left for market makers to cancel stale quotes. Liquidity providers must react faster than ever.

**Dynamic taker fees on crypto markets (still in force since Jan 2026)**

15-minute and 5-minute crypto markets charge takers:

```
   fee = C × 0.25 × (p × (1-p))²
```

Max fee ≈ 1.56% at 50% probability. Near zero at the extremes.

Pure latency arb between Binance and Polymarket is dead — the fee alone usually exceeds the edge.

**The new meta is still: be a maker, not a taker.**

At 50% probability you need >1.56% edge just to break even as a taker. Good luck. Top bots now print from rebates + tight spreads, not from taking.

**WebSocket only**

REST is dead. By the time an HTTP round-trip finishes, the 50ms window is long gone. You need real-time orderbook + trade streams.

**Fee-aware order signing**

You **must** include the current `feeRateBps`

in the signed order.

Query it every time:

`GET /fee-rate?tokenID={token_id}`

Never hard-code. Official SDKs handle this; custom signing must not miss the field or the order is rejected.

**Ultra-fast cancel/replace loop**

Target full cycle (detect price move → cancel → replace) **well under 50ms**, ideally <30ms.

With only 50ms of protection, anything slower gets adversely selected constantly. Colocation or a low-latency VPS near the matching engine is no longer optional — home Wi-Fi is suicide.

**Both-side liquidity + rebates**

Post maker orders on YES *and* NO. That is how you collect the rebate stream.

```
export POLYMARKET_PRIVATE_KEY="0xyour_private_key_here"
pip install py-clob-client   # or the faster Rust options
```

`polyfill-rs`

, `polymarket-client-sdk`

, `polymarket-hft`

).

```
{
  "salt": "...",
  "maker": "0x...",
  "signer": "0x...",
  "taker": "0x...",
  "tokenId": "...",
  "makerAmount": "50000000",
  "takerAmount": "100000000",
  "feeRateBps": "150"
}
```

Still the highest-opportunity venue. 288 markets per day.

Near the end of the window (T-10s), BTC direction is often ~85% determined while Polymarket odds lag.

Post a maker order on the winning side at 90-95¢.

If filled you get the residual + zero fees + rebates.

The edge is now pure speed of pricing + posting before other makers, because the 50ms delay gives almost no second chance.

`feeRateBps`

Give the model the *current* constraints:

“Write a maker bot for Polymarket 5-minute BTC markets. Monitor Binance WS, post maker orders both sides, include live feeRateBps, run cancel/replace under 40ms total latency, use WebSocket orderbook only. Target the 50ms taker-delay environment.”

You define the stack, latency budget, and fee rules. AI fills in the strategy logic. Then **backtest against the current fee curve and the 50ms reality** before going live.

The bots that win after August 17, 2026 are not the ones that take the fastest.

They are the ones that provide the tightest, fastest-updating liquidity and collect the rebates.

Build accordingly.

**Support team links**