# Polymarket Data (SII dataset)

The "107 GB" open Parquet dump of Polymarket CLOB fills, November 2022 to March 2026.

*https://predictionmarkets.tools/tools/sii-polymarket-data · Prediction Market Data APIs*

## Facts

### At a glance

| Field | Value |
| --- | --- |
| Vendor | SII-WANGZJ |
| Category | Prediction Market Data APIs |
| Job | historical |
| Website | https://huggingface.co/datasets/SII-WANGZJ/Polymarket_data |
| Pricing model | open-source |
| Free tier | true |
| Open source | true |
| Licence | MIT |
| Self-hosted | true |
| Tested hands-on | false |
| Last updated | 2026-10-01 |

### Availability

| Field | Value |
| --- | --- |
| Jurisdictions | global |
| Open to US persons | true |
| KYC required | false |

### Markets

| Field | Value |
| --- | --- |
| Subjects | politics, sports, crypto, macro, culture, business |
| Settlement | crypto |
| Resolved by | none |

### Economics

| Field | Value |
| --- | --- |
| Taker fee | none |
| Maker fee | none |
| Liquidity model | clob |
| Platforms | library, cli |
| AI features | none |

### Interfaces

| Field | Value |
| --- | --- |
| API | false |
| WebSocket | false |
| Scripting | none |
| Python | true |
| MCP server | false |
| Export | parquet |

### Capabilities

Yes: none

No: charting, screening, order_book, backtesting, automation, live_trading, paper_trading, portfolio_tracking, calibration_scoring, cross_venue, alerts, news, tax_reporting

*Verified: pricing 2026-09-30; availability 2026-09-30; markets 2026-09-30.*

## What it is

The dataset people mean when they say "the open 107 GB Polymarket dump". A team at the Shanghai
Innovation Institute, with co-authors from Westlake, Shanghai Jiao Tong, Harbin Institute of
Technology and Fudan, decoded every `OrderFilled` event from Polymarket's two original CLOB exchange
contracts on Polygon, linked each fill to its market through the Gamma API, and published the result
as Parquet on Hugging Face together with the MIT-licensed Python pipeline that produced it.

It is published from `SII-WANGZJ`, the personal account of its first author, Zhengjie Wang, on both
Hugging Face and GitHub, not from an account of the institute, and the licence names "Polymarket Data
Contributors" as the copyright holder. The institute is an affiliation, not the publisher.

Five files, each a different cut of the same fills:

| File | What it is |
| --- | --- |
| `orderfilled.parquet` | The raw decoded events: block, transaction, contract, maker and taker, asset IDs, filled amounts, fees, order hash. |
| `trades.parquet` | The same fills with market linkage, outcome name, price and USD amount — the card recommends starting here. |
| `quant.parquet` | Fills normalised to the YES token, contract-side rows filtered out, for price and time-series work. |
| `users.parquet` | Each fill split into a maker row and a taker row, all expressed as buys with signed amounts, sorted by wallet. |
| `markets.parquet` | Market metadata from Gamma. |

It is a Polymarket settlement record, and nothing else: no Kalshi, no order books, no quotes. The
dataset card's own coverage statement is the CLOB era only — first record 21 November 2022, earlier
AMM-era trading from 2020 to 2022 not included — through 4 March 2026.

## Availability

A public, ungated Hugging Face dataset: `hf download SII-WANGZJ/Polymarket_data --repo-type dataset`,
no account required, no jurisdiction attached. The practical gate is disk. The Hugging Face file
listing on 30 September 2026 showed `orderfilled.parquet` at 110.3 GB, `users.parquet` at 47.7 GB,
`trades.parquet` at 37.5 GB, `quant.parquet` at 36.7 GB and `markets.parquet` at 0.3 GB — about
232 GB in all, against the 107 GB the GitHub README still advertises and the 163 GB on the card. The
files can be downloaded individually, and `trades.parquet` alone answers most questions.

## Pricing

Free, with nothing for sale. The dataset card says "MIT License - Free for commercial and research
use" and links the GitHub repository's LICENSE, which reads "MIT License, Copyright (c) 2026
Polymarket Data Contributors" — checked on 30 September 2026. Hugging Face's own licence metadata
field is empty, so the grant for the data rests on that sentence and that link. The README adds that
users are responsible for complying with Polymarket's terms.

## Markets & resolution

Nothing here resolves anything, and there is no resolution column in the documented schemas: a
fill is a fill. Which way a market settled has to come from Polymarket — the
[Gamma API](https://predictionmarkets.tools/tools/polymarket-gamma-api) for the market record or the
[Data API](https://predictionmarkets.tools/tools/polymarket-data-api) for resolution state — joined on the market ID.

## Integrations

Parquet, read with anything that reads Parquet; the README's examples are pandas. The GitHub
repository is the collection pipeline: a Polygon log fetcher, an event decoder, the Gamma market
fetcher and the cleaning steps that produce the derived files, with a "continuous" mode that polls
new blocks every two seconds. An Alchemy key is optional for a faster RPC.

## Limitations

**The pipeline cannot see anything after 28 April 2026.** It decodes the two exchange contracts
listed in the README (`0x4bFb…982E` and `0xC5d5…f80a`). Polymarket moved to new exchange contracts
and a new collateral token that day. Issue #4, "Migrate to CTF Exchange V2", has been open since
30 April 2026 with no reply. A second request of the same kind (#8), opened on 19 May 2026 and
reporting that the pipeline now extracts zero trades, was closed by its own reporter the next day
with no comment from the maintainer and no code change. The "continuous mode" in the README is
therefore a way to record nothing.

**The code has not changed since the day it was published.** Every commit on the default branch is
dated 1 January 2026, and there are no tags or releases. A pull request fixing silently skipped
block ranges (#7) was closed by its own author a minute after opening it, on 17 May 2026, and never
reviewed. The dataset on Hugging Face has moved on — files were replaced on 20 and 21 July 2026 —
but the repository that is supposed to reproduce it has not.

**Completeness has been disputed in public, and the fix is a comment.** Issue #1 on GitHub, opened
12 March 2026, compared the raw files with Goldsky's subgraph and found whole runs of 100 blocks
missing, with up to 26.8% of a day's fills absent. A Hugging Face discussion opened on 12 April 2026
reported about 21% of 2024's blocks missing from the raw files. On 18 June 2026 the maintainer
replied there "I have solved this problem", with no changelog, no version number and no note on the
card. The card still says "no missing blocks or gaps". If completeness matters to your result,
count fills against another source for the window you use.

**Timestamps are reported as wrong.** Issue #3, open since 9 April 2026, found the `timestamp` in
`orderfilled.parquet` disagreeing with the Polygon block timestamp in 100 of 100 sampled fills. Use
`block_number` and look the time up yourself.

**The size, record counts and coverage dates disagree across its own pages.** README, card and file
listing give three different totals; the card's "Last Updated" of 5 March 2026 predates the July
file replacement, and what the replaced files cover is not stated anywhere.

**No order books.** A Hugging Face discussion asking for them, opened 21 April 2026, has no reply. Depth is
not recoverable from fills.

## Alternatives

[Prediction Market Analysis](https://predictionmarkets.tools/tools/prediction-market-analysis) is the other free archive, smaller,
covering Kalshi as well as Polymarket, with analysis scripts attached. For Polymarket fills that
continue past April 2026, the [Goldsky Polymarket datasets](https://predictionmarkets.tools/tools/goldsky-polymarket-datasets) are
the maintained version of the same decoding, paid by the row, and
[Polymarket dashboards on Dune](https://predictionmarkets.tools/tools/dune-polymarket-dashboards) put it behind SQL. For order-book
history, which no fill dataset contains, see [Marketlens](https://predictionmarkets.tools/tools/marketlens).

## FAQ

### Is this the same dataset as Prediction Market Analysis?

No. Prediction Market Analysis is Jonathan Becker's framework with a roughly 36 GiB archive of Kalshi and Polymarket trades. This one is a separate Polymarket-only dataset from a team at the Shanghai Innovation Institute, decoded from Polygon OrderFilled events, and it has no Kalshi data at all.

### How big is it really?

Bigger than the headline. The GitHub README says 107 GB and 1.1 billion records; the Hugging Face card says 163 GB and 1.9 billion; the five files listed on Hugging Face on 30 September 2026 add up to about 232 GB, most of it the raw OrderFilled file at 110 GB.

### Does it include trades after Polymarket's April 2026 contract upgrade?

Not from the published pipeline. The code decodes the two original exchange contracts, and an issue asking for CTF Exchange V2 support has been open since 30 April 2026 without a reply. The dataset card's stated coverage ends on 4 March 2026.

### Can I use it commercially?

The dataset card says MIT, free for commercial and research use, and links the repository's MIT licence. The Hugging Face metadata carries no licence field, so the grant rests on that prose and that file. The underlying rows are public blockchain events.

## Background

- [What a trade actually costs on a prediction market](https://predictionmarkets.tools/guides/what-a-trade-actually-costs.md) — Venues publish trading fees in four incompatible units, so 3.00% on one can be cheaper than 1.75% on another. How to convert them, and what else takes a cut.
- [Where weather data comes from and what you may do with it](https://predictionmarkets.tools/guides/where-weather-data-comes-from.md) — Observations, model output and archives are three products with three licences. The forecast is the cheap half; a clean observation history is not.

- [Why the same contract costs two different prices on two venues](https://predictionmarkets.tools/guides/why-the-same-contract-costs-two-prices.md) — Two venues quoting one outcome are quoting two contracts. What the gap between the prices is made of - rules, fallbacks, fees, collateral, exits, eligibility.

## Also worth comparing

- [Goldsky Polymarket Datasets](https://predictionmarkets.tools/tools/goldsky-polymarket-datasets.md) — Polymarket's on-chain fills and positions, backfilled and streamed into your own database.
- [Marketlens](https://predictionmarkets.tools/tools/marketlens.md) — Recorded Polymarket order books across every market type, replayable to the tick.
- [Polymarket Data API](https://predictionmarkets.tools/tools/polymarket-data-api.md) — Polymarket's keyless read API for trades, positions, holders and price history.
- [DepthFeed](https://predictionmarkets.tools/tools/depthfeed.md) — The recorded bid-ask ladder for crypto up-or-down markets, which no venue keeps itself.
- [PolyOrderbooks](https://predictionmarkets.tools/tools/polyorderbooks.md) — Recorded L2 books for Polymarket crypto markets, priced by how far back you may look.
- [Predexon](https://predictionmarkets.tools/tools/predexon.md) — Tick-level book history as Parquet, billed by the gigabyte, plus a mempool-aware feed.