Opening Lab

Primary Workflow

Analyze Opening Variance

Core Setup

Main Sample Definition

Point the job at a real PGN file and define the canonical line filter once.

PGN or PGN.zst path Path to a .pgn or .pgn.zst file the engine will analyze. Tip: use the Lichess Bulk Source tab to download an archive first. Opening SAN prefix Opening line in Standard Algebraic Notation, e.g. d4 Nf6 Nc3 g6 Bf4. Only games beginning with this exact sequence are analyzed.

SAN is checked inline and again on submit against a legal move sequence from the starting position. This is the canonical line input for the page.

Live Preview

Renders after the SAN prefix above. Updates live as you edit.

Sample Window

Player Pool And Clock

Constrain the games to the rating band and time range you actually care about.

Players

Rating Window

Use Elo ranges to describe who is playing White and Black.

Clock

Time Control Band

Filter by base time and increment using ranges instead of a separate exact field.

Engine

Evaluation Logic

Choose the engine, target ply, and thresholds used to classify early pressure.

Engine

Search Setup

Pick the engine family and how deep it searches each position.

Engine Depth

Workflow

lc0 reuses the engine path / weights / backend above. Provide the Maia engine binary and weights below.

Maia engine path Maia weights Maia backend

Thresholds

Edge Definitions

Define what qualifies as an early edge or a practical crush.

Target ply Edge threshold Pawns of advantage that qualify as an "early edge" for White at the target ply. Drives the early_edge_rate metric. Crush threshold Pawns of advantage that qualify as an "early crush" for White at the target ply. Drives the early_crush_rate metric. Default 2.0 ≈ nearly winning.

Guardrails

Workload Caps

Keep large monthly archives from turning into unbounded scans.

Max evaluated games Max scanned games

If your opening is rare, the scan cap stops the job early and returns a partial sample instead of walking the whole month.

Browser Sweep

ChessBase Curated Search

Seed Search

Native ChessBase Terms

Start with a player, event, year, or leave query blank and inherit the main line only.

Primary query Main quick-search term sent to ChessBase, e.g. an opening name like Jobava or a player name. Additional quick terms

Each line becomes its own ChessBase quick-search chip. If this is blank and you pick a specific White or Black player below, that player name is used as the search seed automatically.

Override

ChessBase Board Filter

Optional. Leave blank to reuse the main line filter from the analysis form.

Board SAN prefix Opening moves in SAN, e.g. d4 Nf6 Nc3 g6 Bf4. Sets the board state before searching.

SAN is the canonical opening-prefix input. Leave it blank to inherit the main line filter from the analysis form.

Local Filter

Player And Metadata Filters

Pick one White filter mode and one Black filter mode. A named player and an Elo range should not be mixed on the same side.

White

White Filter

Choose Any, a specific White player, or a White Elo range.

White filter mode

White player name

Black

Black Filter

Choose Any, a specific Black player, or a Black Elo range.

Black filter mode

Black player name

Year min Earliest game year to keep, e.g. 2024. Local post-filter. Year max ECO prefix ECO opening-code prefix, e.g. D0 matches D00–D09; D02 is exact. Local post-filter.

Result Game result filter: 1-0, 0-1, or 1/2-1/2. Local post-filter.

Runtime

Browser Session And Exports

Control how much of the site is scraped and where CSV or PGN output lands locally.

State file Path to a Playwright storageState.json for a logged-in ChessBase session. Required for premium queries. Output CSV Output PGN

Rows to collect Timeout ms Headless

Extract full games into PGN during search

Native ChessBase filters happen first. Time control is still not exposed by the current ChessBase web surface, so exact clock filtering remains stronger on Lichess dumps.

Archive Dock

Lichess Bulk Source

Download

Archive Fetch

Pull a rated Lichess archive into your local data/lichess folder for bulk filtering and engine analysis.

Dataset Lichess archive variant. standard is normal chess; other values include antichess, crazyhouse, atomic, etc. Month Year-month of the archive to download, format YYYY-MM (e.g. 2026-02). Leave blank to grab the latest. Output dir Local folder where the .pgn.zst file will be saved. Default data/lichess.

Overwrite existing file

Reference

Available Dumps

Use this as a quick index, then copy one downloaded path into the analysis input above.

Decision Reps

Weakness Trainer

Scenario set

Pick a scenario set to start, or generate a fresh one above. The clock starts the moment a position loads — make your move on the board.

0.0s

Progress

Decision Stats

No reps logged yet. Your decision time and accuracy will accumulate here as you train.

Opponent Prep

Prep vs player

Enter a Lichess username and the color they play. We fetch their public games, index them, and rank their replies by where they score worst, so the strongest moves against them surface first.

Submit a username to build the weighted opening tree.

Analyze Opening Variance

Main Sample Definition

Player Pool And Clock

Rating Window

Time Control Band

Evaluation Logic

Search Setup

Edge Definitions

Workload Caps

ChessBase Curated Search

Native ChessBase Terms

ChessBase Board Filter

Player And Metadata Filters

White Filter

Black Filter

Browser Session And Exports

Lichess Bulk Source

Archive Fetch

Available Dumps

Opening Explorer

Opening Line

Speeds And Ratings

Evaluation Logic

Search Setup

Edge Definitions

Weakness Trainer

Decision Stats

Prep vs player

Weakness Evolution

Select a job or launch a new one