Market making
Polymarket and Kalshi market-making bots
Open-source market-making bots for Polymarket and Kalshi, with strategy, setup, activity and the failure modes operators report.
Checked September 8, 2026 · every price read off the live site
Every market making bot
1 reviewed · alphabetical-
Kairos Cross-venue trading terminal: Kalshi, Polymarket and Predict.fun in one order book, with sub-second data and advanced order types.
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02poly-maker The most-starred genuine community bot: maker-only market making on the Polymarket CLOB, quoting both sides. Earns the spread instead of paying it.
| Bot | Venues | Pricing | Type |
|---|---|---|---|
| poly-maker | Polymarket | Open source (MIT) | bot |
How these bots work
Market-making bots quote both sides of a prediction market and earn the spread, liquidity rewards and maker rebates instead of paying the spread as a taker. On Polymarket that means post-only bids for YES and NO that sum below $1, so a filled pair merges back to collateral at a locked edge.
The hard parts are not the quoting. They are inventory skew, adverse selection from informed flow, and pulling quotes fast when news hits. A maker bot without a regime machine and a kill switch is a bot that gets picked off.
The open-source field is thin. poly-maker is the one purpose-built maker with tests and paper mode; DRADIS and CloddsBot each carry a maker strategy inside a larger engine.
How to choose
- Post-only enforcement: every order should be maker-only by construction, not by hoping the price does not cross.
- Inventory and toxicity handling: look for skew by net position and spread widening from realized volatility and per-fill markout.
- A regime machine or equivalent that pulls quotes on sweeps and near resolution, plus a daily-loss kill switch and a WebSocket staleness halt.
- Paper mode against the live feed before any live size, and a cancel-all panic command.
- Venue fit: Polymarket CLOB V2 signing and rewards bands are specific; a generic exchange bot will not know them.
Questions about market making bots
Is market making on Polymarket profitable?
poly-maker's README says it is competitive and can lose money, and publishes no returns. Rewards and rebates are the documented income sources; adverse selection is the documented cost.
What is the best open-source Polymarket market maker?
poly-maker has the most stars (1,489) and the most complete maker-only design in this directory. DRADIS includes a Maker strategy among nine.
Can I market make on Kalshi with an open-source bot?
DRADIS's Kalshi build includes its Maker strategy. No purpose-built Kalshi market maker with meaningful adoption appears in GitHub search results for kalshi bot as of 2026-09-08.
Bots die in execution. Terminals are execution.
Wanted a bot for speed and cross-venue vision? The free Kairos terminal trades Kalshi, Polymarket and Predict.fun from one book, no keys to manage.