---
license: cc-by-4.0
pretty_name: Polymarket Crypto Up/Down Order Books — 1-Second L2, Three Contract Lengths
task_categories:
  - time-series-forecasting
  - tabular-regression
language:
  - en
tags:
  - polymarket
  - prediction-markets
  - order-book
  - order-books
  - limit-order-book
  - market-microstructure
  - high-frequency
  - crypto
  - bitcoin
  - ethereum
  - solana
  - xrp
  - dogecoin
  - backtesting
  - slippage
size_categories:
  - 100K<n<1M
configs:
  - config_name: default
    data_files:
      - split: train
        path: "*.parquet"
---

# Polymarket Crypto Up/Down Order Books — 1-Second L2 Depth

**897,192 order book snapshots across 805 resolved markets and three contract
lengths.** Full bid and ask ladders, captured once per second, with the winning
outcome on every row.

This is the DOI-carrying research release. Same data as
[10.5281/zenodo.22084114](https://doi.org/10.5281/zenodo.22084114), mirrored here
for `load_dataset`.

## What is in it

| File | Snapshots | Markets | Contract |
| --- | --- | --- | --- |
| `updown_5m.parquet` | 167,941 | 471 | Five-minute |
| `updown_15m.parquet` | 239,310 | 265 | Fifteen-minute |
| `updown_4h.parquet` | 489,941 | 69 | Four-hour |

Eight coins. Every market resolved, so each row carries its outcome. One
continuous collector regime, so the three files are comparable with each other.

```python
from datasets import load_dataset
ds = load_dataset("polyorderbooks/polymarket-crypto-updown-orderbooks-l2")
```

## Why three contract lengths

Because conclusions do not transfer between them, and that is easy to miss with
one.

| | 5-minute | 15-minute | 4-hour |
| --- | --- | --- | --- |
| One-sided snapshots | 16.9% | 9.3% | **0.5%** |
| Crossed snapshots | 3.24% | 3.08% | 1.50% |
| One-sided in the final 60s | 76.2% | 85.4% | 46.5% |

A four-hour contract holds a two-sided market for almost all of its life. A
five-minute contract does not. Anything measured on one length should be checked
against another before it is described as a property of prediction markets.

## Two things to expect

**Books go one-sided as markets resolve.** Nobody offers the losing outcome and
nobody bids the winning one. This is real market behaviour, not missing data, and
it will break code that indexes the first level of a ladder without guarding.

**Some snapshots are crossed** — best bid at or above best ask, which cannot
persist in a matching engine. They are flagged rather than removed so the rate
stays measurable:

```python
import pandas as pd
df = pd.read_parquet("updown_5m.parquet")

(df.best_bid >= df.best_ask).mean()              # crossed rate
(df.bid_prices.str.len() == 0).mean()            # empty bid side
df[df.seconds_to_close <= 60].crossed.mean()     # and near settlement
```

Publishing the flag rather than filtering the affected rows is deliberate: you
can measure our data quality instead of taking our word for it.

## Schema

One row per outcome token per second. Ladders are typed list columns, so no
parsing step.

| Column | Type | Notes |
| --- | --- | --- |
| `market_slug` | string | e.g. `btc-updown-5m-1787551200` |
| `outcome` | string | `Up` or `Down` |
| `captured_at` | timestamp | UTC, 1-second resolution |
| `seconds_to_close` | float | Time remaining until settlement |
| `bid_prices`, `bid_sizes` | list[float] | Full bid ladder, best first |
| `ask_prices`, `ask_sizes` | list[float] | Full ask ladder, best first |
| `best_bid`, `best_ask` | float | Derived top of book |
| `crossed` | bool | `best_bid >= best_ask` |
| `winning_outcome` | string | Resolved result |

Prices are probabilities in [0, 1]. Sizes are share counts.

## How it was captured

Read from Polymarket's live order book once per second, with a full-book
reconcile every 60 seconds. The reconcile interval is the design decision that
matters: replaying an archived event stream instead diverges from the source at
roughly two-thirds of checkpoints, because the feed carries no sequence numbers
and a dropped removal leaves no gap to detect.

Polymarket archives no order book history itself — `/book` returns the current
state and nothing stores it — so this data exists only because it was recorded
while the markets traded.

## Citation

> PolyOrderbooks. (2026). *Polymarket Crypto Up/Down Order Books: 1-Second L2
> Depth Across Three Contract Lengths* [Dataset]. Zenodo.
> https://doi.org/10.5281/zenodo.22084114

That is the concept DOI and always resolves to the newest version. Each version
also has its own DOI for pinning exact data.

---

## About PolyOrderbooks

We capture Polymarket order book depth at 1-second resolution and serve it over a
REST API. Polymarket archives no order book history of its own — its `/book`
endpoint returns the current state and nothing stores it — so this data exists
only because it was recorded while the markets traded.

| | |
| --- | --- |
| API | [polyorderbooks.com](https://polyorderbooks.com) |
| Documentation | [docs.polyorderbooks.com](https://docs.polyorderbooks.com) — endpoints, parameters, response shapes |
| Free tier | [polyorderbooks.com/signup](https://polyorderbooks.com/signup) — 1-second resolution, no card |
| All open datasets | [polyorderbooks.com/datasets](https://polyorderbooks.com/datasets) |
| Python client | [`pip install polyorderbooks`](https://pypi.org/project/polyorderbooks/) |
| MCP server | [`@polyorderbooks/mcp-server`](https://www.npmjs.com/package/@polyorderbooks/mcp-server) — for Claude, Cursor and other MCP clients |

### The citable release

For a paper, cite the DOI-carrying release rather than this repository — 897,192
snapshots across 805 resolved markets and three contract lengths, same schema,
same licence:

> PolyOrderbooks. (2026). *Polymarket Crypto Up/Down Order Books: 1-Second L2
> Depth Across Three Contract Lengths* [Dataset]. Zenodo.
> https://doi.org/10.5281/zenodo.22084114

### Questions

Open a discussion on this dataset for anything about the data itself.

For the API — a window these files do not reach, a coverage question, a plan —
email **contact@polyorderbooks.com**. Corrections to the data are welcome and
taken seriously; if you find something wrong here we would rather know.

Not affiliated with, endorsed by, or connected to Polymarket.