Best Polymarket Order Book Data

The ranking rewards whoever does the specific job best, not whoever has the most features. The full matrix that underpins it covers 10 providers across historical prices, historical L2, resolution, free tiers, and bulk export. Facts below were verified against public pricing and docs pages on September 24, 2026, and recorded in our provider matrix.

• 1. PolyOrderbooks — for 250ms interval-sampled full bid/ask ladders with prices and metrics, free Starter tier included, and resolved markets that stay queryable.
• 2. Telonex — for event-driven book snapshots at multiple depths (5, 25, full) and tick-level trades in Parquet for multi-exchange research.
• 3. Predexon — for historical order books with free unlimited historical endpoints on every plan, across multiple venues.
• 4. DepthFeed — for event-driven full-depth ladders across Polymarket, Kalshi, and Limitless on paid plans.
• 5. PolymarketData — for timestamped L2 snapshots at a documented 1-minute resolution from August 2025.
• 6. PolyTest — for Up/Down backtests against snapshots captured with 8 documented depth levels.
• 7. PolyBackTest — for BTC/ETH Up/Down full-depth point-in-time queries on a shallow accumulating window.

Measured coverage is the part a marketing page cannot answer. Our archive captures order books every 250ms and serves every plan, including free Starter, at that same 250ms query resolution. Competitors in the matrix cap documented L2 detail at 1-minute (PolymarketData), at 8 levels per snapshot (PolyTest), or rely on self-reported sub-second claims that conflict across their own pages (PolyTest, PolyBackTest). Resolution is not the only axis. Read the matrix row for interval-sampled versus event-driven capture (Telonex, DepthFeed), for on-chain-only limits that exclude the off-chain book entirely (Dune), and for archives that stop at coverage end or endpoint shutdown (polyReplay, Dome). Each listed product is the best answer for a specific job, and none is the best answer for every job.

Free tiers matter when the honest answer is the official API — which it usually is for live prices. Every provider in the matrix lists its free tier; where the free tier is only a sample or a trial, the row says so. If the job is historical depth, expect to pay for it, because depth history is the expensive thing to keep.

The exact order-book shape you need is the top-of-book plus the ladder, with both sides, at a stated UTC second. Two providers return that identically; the difference shows up when the second is inside a reprice, when one side empties and the executable price jumps a full band in under a second.

Verify book data against a known event: the linked reference fell across the family in 26 seconds on the recorded day. The provider who reproduces that hour faithfully — floors, ladder, sides, and all — is the one that can be trusted with every other window.

The depth read, not the mid, is what your strategy should consume; a provider that pushes top-of-book quotes while dropping the ladder leaves out the venue's defining one-sidedness.

The empty-side second is the honest unit test: an order-book source that reproduces the frame where the executable side empties before the bound moves has the data; one that smooths it to a steady chart does not, regardless of latency claims.

Pull the same reprice hour from two sources and diff the depth columns row by row; agreement at that level is the only real quality signal.

Prefer full-ladder snapshots at 250ms over summary endpoints, since summaries cannot be re-derived later.

Match the cadence guarantee to your strategy: a one-second strategy that subscribes to five-minute snapshots is paying for unusable data.

• Full provider matrix
• Order book data
• Price history
• Data download