Polymarket vs Kalshi MLB Data — Matched Order Books

MLB matched quotes, corrected v2 build: 1,185,227 rows across 733 dated games. Nearest-time joins and coverage limitations are disclosed.

Full schema & known gaps →· Sold as-is — but if a file is broken or won't open, email [email protected] and we'll send a fixed file or refund you. No hassle.

Not ready for $199? Start with the $9 MLB sample — 21,053 rows across 28 game-day keys (26 settled, 2 unresolved), using the same schema.

Artifact vintage: the product page and shipped documentation state the exact coverage, row counts and known limitations. A purchase delivers the advertised frozen artifact; no future refresh is promised unless the checkout terms explicitly say so.

Why the capture contract matters

Venue APIs expose useful live books, trades and price history, but they do not serve the same historical snapshot and game-context archive packaged here. Data that was not recorded during the live window cannot be recreated from a current-book endpoint later. The exact fields, cadence, venue coverage and limitations vary by product, so this page and the shipped documentation state the contract explicitly instead of calling every file complete or tick-level.

What's in the dataset

WITHDRAWN · 1,185,227 rows · 733 dated games · 55 captured game dates · UTC-boundary v2

Research uses for this dataset

Cross-venue quote comparison

Compare sampled prices with the nearest-time join offset; this archive alone does not establish which venue moved first.

Quoted spread research

Inspect sampled bids and asks with freshness and one-sided-book limitations; quoted gaps are not demonstrated fills or profit.

Outcome-aware studies

Group quote behavior by the finalized market result without building a separate settlement join.

Coverage-aware backtests

Use the manifest and per-day counts to keep missing capture windows out of the test set.

See the real rows before you buy

We publish real sample rows — not a marketing mockup. Load them in DuckDB, inspect the schema and coverage contract, then decide.

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