Aperiodic
MarketsLive
Pricing
Get Started

L1 & L2 order book

From the best bid and ask down to 25 levels: spread, depth, imbalance and the mid.

Shown: an illustrative order book over time, bids below the mid and asks above it.

5 datasets

L1 liquidity

Spread and dollars at the touch

BTC's spread on Binance was one tick in 99.5% of May's bars. Depth at the touch was 1.5× as large at 10:00 UTC as at 21:00.

14 fields · PrimeBTC now $1.1M

L1 imbalance

Bid against ask size at the touch

BTC's top-of-book imbalance correlated 0.38 with the move in its own bar and 0.002 with the next.

10 fields · Prime

L1 price

Best bid and ask, mid and microprice

The microprice got the direction of BTC's next 5-minute move right 52.3% of the time.

12 fields · Pro

L2 order book liquidity

Size resting 5 to 25 levels deep

74% of the BTC within 25 levels of Binance's book sat at the best bid and ask.

16 fields · PrimeBTC now $1.1M

L2 order book imbalance

Bid against ask size, 5 to 25 levels deep

On BTC, deeper imbalance tracked the bar less, not more: 0.37 at 5 levels, 0.33 at 25.

24 fields · PrimeBTC now -0.088

Fields to start with

spread_bps
Last bid-ask spread in basis points of the midprice
L1 liquidity
total_dollar_depth
Last total top-of-book notional across bid and ask
L1 liquidity
imbalance_ratio
Last normalized difference between best-bid and best-ask quantity
L1 imbalance
weighted_midprice
Midprice weighted by the opposite-side top-of-book quantity
L1 price
imbalance_ratio_10
Last normalized difference between top-10 bid and ask quantity
L2 order book imbalance
bid_agg_10
Last total bid quantity across the top 10 levels
L2 order book liquidity

What it's used for

Costs in backtests

What crossing the spread cost, and how much size rested at the touch, bar by bar.

Book pressure

Bid against ask size at the touch and 5 to 25 levels deep, as a feature or a filter.

A better mid

The weighted mid leans toward the thinner side of the book: a fairer price than the plain mid when one side is much deeper.

Liquidity across venues

See where and when depth thins, perp by perp, without storing book snapshots.

Every field, with its endpoint and code, is in the Data Catalog.

For the background, the microstructure guide has a chapter on the order book and the spread.

Aperiodic

Built from hundreds of terabytes of raw data and distilled into point-in-time metrics you can pull as parquet files. Plus the raw trades, quotes and derivatives data behind them.

Use Cases
  • Improve your backtest
  • Find new alpha
  • Execute smarter
Indices
  • All indices
  • Aperiodic Cost Index
  • Aperiodic Depth Index
  • Aperiodic Impact Index
Metrics
  • Metrics library
  • Data Catalog
  • Live markets dashboard
  • Global Liquidity
  • Unusual activity
  • Order Flow
  • L1 & L2
  • Derivatives
  • RWA
  • Raw Data
Developers
  • API Docs
  • Live WebSocket Feed
  • MCP Server
  • Notebooks
  • For AI Agents
  • Atlas Security Master
  • Pre-flight
  • Changelog
  • Roadmap
  • llms.txt
Learn
  • Replays
  • Microstructure Guide
  • Architecture
  • Research Blog
  • FAQ
Compare
  • All vendors
  • vs. Tardis
  • vs. CoinGlass
  • vs. Kaiko
  • vs. Amberdata
Company
  • Pricing
  • Contact
  • Book a call
  • Terms of Service
  • Privacy Policy
  • Licensing
  • SLA

© Copyright 2026 Aperiodic. All Rights Reserved.

Aperiodic Limited · Registered in Ireland · Company No. 815273 ·
136 Capel Street, Dublin D01 T2C9, Ireland

Shown: minute closes of 847 perpetuals, 20:30–22:30 UTC on 10 Oct 2025, IOTX in orange · built with ohlcv 1m