Please wait...
This is usually caused by an outdated cached file, a browser extension blocking scripts or cookies, or filtering by a VPN, security program, company network, or public Wi-Fi.
Please try:
If the problem continues, contact support with your device, browser, and a screenshot. Never include your password.
Sign in to Opening Lab.
Login failed.
Select a node in the repertoire move tree.
Load a PGN file to begin.
Building move list...
-
Game Data
| Move | Rep. | White | Draw | Black |
|---|
Expected Moves
Evaluation of final position
...An opening repertoire is your personal plan for the beginning of a game: the lines you want to play and the answers you prepare for likely replies.
To start, import a PGN repertoire or a public Lichess Study. If you do not have one, use a pre-made Opening Lab repertoire, build a repertoire from online games, or create your own repertoire with the help of the app. You can start small—no need to cover everything immediately.
Daily Training is the recommended routine. To reinforce, you can also train specific areas with Customized Training or spar against realistic opening replies.
Practise the repertoire moves that are due today.
Choose a repertoire, side, mode, and starting move.
Play realistic opening replies, get move-quality feedback, and revisit important decisions.
Use your games and engine-backed reports to find gaps, update your repertoire, and train the improved lines again.
Compare your games with your repertoire and find deviations.
Find weak moves and important missing replies.
Refine lines and add relevant missing opponent replies.
Find an opponent’s opening weaknesses and likely deviations from the lines covered in your repertoire.
You can explore the app immediately. These two tools work without creating or importing a repertoire first.
Choose either side, face realistic opening replies, and review serious mistakes afterward.
Analyze an online player or uploaded PGN for repeated weak opening moves.
Use the lightbulb to let Opening Lab suggest which opponent moves your repertoire should cover. Suggestions follow your selected rating and time-control filters and the chosen Breadth & Depth level.
No help topics match this search.
Opening Lab helps you build, manage, analyze, and train chess opening repertoires. It combines PGN repertoires, move-tree browsing, explorer data, reports, and spaced training in one workflow.
Opening Lab runs in a modern web browser and can be used on desktop and laptop computers, tablets, and smartphones. This includes Windows, macOS, Linux, iPhone, iPad, and Android devices. Simply open Opening Lab in a current version of a mainstream browser and log in with your account. No software installation is required. A larger screen is more convenient for editing extensive repertoires and reviewing detailed reports, while training and the other core functions are also designed for mobile use.
There is currently no separate Opening Lab app in the Apple App Store or Google Play Store. Opening Lab is a web app, which means that the same current version can be used across devices without installing or updating a separate app.
You can add Opening Lab to your mobile device's Home Screen for quicker access:
This creates an Opening Lab icon on the Home Screen. It does not install a separate offline version, so an internet connection is still required.
An opening repertoire is your prepared set of lines for the openings you choose to play. It defines which positions you aim for, which opponent replies you are ready to meet, and where your middlegame plans begin. Ambitious players need one because it makes opening study concrete: you can avoid random memorization, repeat important positions, identify gaps, and build confidence in the structures you actually play.
Open Repertoire Management and select +. Choose Import PGN to upload your own files, choose Import Lichess Study to select and import usable chapters of a public study, choose Opening Lab Repertoire for free repertoires provided by the app, choose Build from Online Player to create an editable snapshot of a Lichess or Chess.com player's opening habits, or start creating your own repertoire by entering a repertoire name, side, and coverage option and selecting Open Editor.
These include white repertoires based on either 1.e4 or 1.d4 as well as black repertoires against anything that seems practically relevant. The repertoires were generated based on available game data aiming to produce a nice blend of solid yet practically effective repertoires. These repertoires should be a good basis for customizing and refining further using your own preferences and/or the analysis tools Opening Lab offers.
Your repertoires are listed under Repertoire Management on the main page. Each entry provides access to its move tree, unified editor, PGN/PDF exports, repertoire analysis, Critical Positions and Difficult Moves reports, rename and delete actions, the Daily inclusion switch, and Training Depth. Training Depth limits Daily and Customized Training after the selected repertoire-side move, while deeper course material remains available in the editor, move tree, and exports.
Both options open the same editor. Broad repertoire lets continuous opponent-move suggestions search across all relevant paths in the growing repertoire. Specific line keeps that search on the path you are building. The setting affects suggestion coverage, not your ability to add legal alternatives manually.
Open the repertoire editor from the library to start at the original position, or open it from a move-tree or training position for a contextual start. Current Path shows how you reached the board position. Existing Repertoire Moves shows the saved continuations you can select to navigate. Play another legal move on the board to add an alternative. The symbol toolbar provides navigation, Undo, Redo, suggestions, Save, global delete or replace, line and position details, PGN export, and Close; each symbol has an explanatory label. Explorer data, Master Games, and Open Analysis are available beside the board. Critical positions can be marked from training or the move tree.
A Critical Position marks a whole chess position for focused review and Critical Positions training; an optional short name makes it easier to recognize. A Position Note belongs to that position and therefore also appears when a transposition reaches it. During training the note is indicated before the answer and can be opened on demand, so it does not flash briefly or reveal the solution unintentionally. A Line Tag labels one complete trainable line, not every branch sharing its opening moves. These details synchronize with the repertoire and are included in annotated PGN and critical-position reports where applicable. Choose Opening Lab PGN to preserve Position Notes and Line Tags exactly for reimport, or Clean PGN to keep readable annotations without Opening Lab markers for other chess tools. For other PGNs, one import summary lets you import all suitable course comments as Position Notes or skip them. Connected PGN prose is kept together with its move context, and all comments for the same position are consolidated into one editable Position Note.
Select the position where the new branch should begin, then play the new legal move on the board. This adds an alternative and leaves existing own and opponent moves intact. Additions are position-based, so the new alternative can also appear in other paths that reach the same exact chess position. The impact message shows how many position occurrences and line paths are affected.
Delete move globally removes the selected move wherever it occurs from the same exact position, including transpositions. Select Save to delete it, or play a different legal move before saving to replace it everywhere atomically. Other alternatives remain unchanged. Replacement and deletion stay in the draft until Save is selected, and the impact summary and confirmation show how many position occurrences and line paths are affected.
Select the suggestion button to switch suggestions on. At an opponent position, Opening Lab searches the most relevant repertoire paths first for the next uncovered move that meets the Opponent Move Suggestions — Breadth & Depth setting. After it stages that opponent move, play your own reply; suggestions remain on that line while qualifying continuations exist and only then move to the next relevant path in the selected scope. A search pass pauses after five seconds; select Suggestions again to continue from the saved progress. Suggestions also stop when you save or leave the editor, when no qualifying uncovered move remains, or when position data cannot be loaded. Suggested changes stay in the unsaved draft until you select Save.
If you try to close the editor with unsaved repertoire changes, Opening Lab asks whether to discard them or continue editing.
Open Repertoire Management, find the repertoire, and use its PDF export button. The export creates a printable repertoire tree.
Daily Training creates a plan to learn all repertoires marked as Daily in Repertoire Management. It supports efficient learning by using spaced repetition. The number of daily moves to be trained is defined so it allows steady progress in learning the relevant repertoires.
You have two options: First, you can add another Daily round by selecting Start Another Round upon completion. Use this sparingly because it adds work today and can also increase future reviews. Second, you can use Customized Training after Daily Training. Pick the repertoire and mode you want, or use Random Lines, Random Positions, Critical Positions, or Difficult Moves to continue practising beyond the daily queue.
When First-Time Guidance is On, it shows one arrow for each new own repertoire move, starting with the earliest new own move in the line. It is not used when training Opponent Moves. If a position has several own repertoire moves, each new alternative is introduced separately. Guided solutions are recorded separately from unguided correct and wrong moves; later attempts count as normal training. The introduced-move state is included in training-progress synchronization. The ? button is separate manual help and does not turn a prompt into First-Time Guidance.
Use the ? button in the training modal to reveal the expected move. After revealing, play through the move and continue; the position remains useful for review instead of becoming a guessing exercise.
If training is still in the same line, use Open Analysis before continuing to review the position, options, evaluations, and to navigate back and forth in the line. Also, the position will be shown again towards the end of the training so you can retry and review it then.
After each move, Opening Lab briefly highlights the move squares as feedback:
Green means the move was correct, i.e. the repertoire move.
Red means the move was wrong and likely significantly worse than the repertoire move.
Orange means the move was wrong, but the evaluation difference appears moderate.
Yellow means the move was not the repertoire but a viable alternative as the evaluation difference appears relatively small.
Blue means the move was already tried or is illegal.
These meanings apply to repertoire training. In Opening Sparring, every legal move is accepted. The board highlight and move text show engine-based move quality: green means Excellent, yellow means Playable, orange means Inaccuracy, and red means Mistake or Poor. This assessment is separate from repertoire coverage, so a move outside the repertoire can still be Excellent. If no reliable evaluation is available, no quality colour is shown.
Select Opening Sparring on the main page. Its setup lets you choose an optional repertoire, the side to play, and an optional starting position. Select Position opens a move tree in which you can play moves on the board or choose moves from Move Explorer. Select Main Settings to choose Online Games or Master Games as the game-data source.
If a repertoire is loaded, choose Play my repertoire or Play against my repertoire. When you play your repertoire, Opening Lab selects opponent moves without limiting them to your repertoire. When you play against your repertoire, Opening Lab uses an available repertoire move. Without a repertoire, choose White or Black; every legal user move is accepted.
Opening Lab normally replies with a common indexed move. If no further common move is available or the opening limit is reached, you can still make one final move and receive feedback before the summary opens. Checkmate and stalemate end immediately. The final evaluation uses White's perspective: + means White is better and - means Black is better.
Opening Lab distributes the unmodified Stockfish.js browser engine under GPLv3. License · Corresponding source
Game Data shows the historical White, Draw, and Black results after each move for the selected source and filters. A result of at least 50% is highlighted green when it favours your side and red when it favours the opponent. Results based on fewer than ten games are marked as a small sample and are not given this majority highlighting. These historical results are not engine evaluations.
The Rep. column is shown only for your own moves when you selected Play my repertoire: ✓ means the move belongs to the repertoire, ✕ means another repertoire move was available, and – means the repertoire has no continuation in that position. The ✕ uses the move-quality colour when an evaluation is available; it does not by itself mean the move was bad. Select a symbol to see its details. Opponent moves are not marked.
The completion summary lists Decisions to revisit: your repertoire deviations and moves rated Mistake or Poor. Select a listed move to return to the position before it. Find a repertoire move when one is available; otherwise, find a sound move.
Reveal move draws arrows for the repertoire alternatives, or for a Stockfish suggestion outside the repertoire. Select Back to summary to return to the completed game.
Training Entry Mode controls where Daily or prompt-based Customized Training starts within a line. Target Moves Only asks only the moves selected for the current session, without additional access-move prompts. Daily targets contain all due moves plus the planned new moves; in Specific Lines, every own move after the selected position is a target, irrespective of due status. First New Move starts from the first unresolved move needed for the selected line. Always Start At Move 1 starts from the beginning of the line and asks the relevant own-side access moves before the target.
Training Entry Mode controls where a line starts. Under Training Flow, Manual Advance waits for the Next button after a completed line or position, while Auto Continue moves to the next target automatically in Daily and Customized Training. First-Time Guidance can introduce each new own repertoire move with a one-time arrow, and Auto-Play Speed controls the transition speed.
Either select Specific Line in Customized Training or open Repertoire Management and browse a repertoire's move tree. Select the position where training should begin, then choose Train.
In Customized Training, change Side To Be Trained from Own Moves to Opponent Moves. Opponent training uses Random Positions because covered opponent moves are aggregated by exact position, including alternatives reached through transpositions. Use Positions Starting From Move to control the depth. Solve all covered alternatives shown for each position.
Opening Lab provides several PDFs for different study tasks:
The Help PDF is a general manual rather than a personalized chess report.
Critical Positions are selected manually. Use them for positions you consider especially important, complex, or worth revisiting—even if you have never answered them incorrectly. They can involve either your move or an opponent reply and may have a custom name, Position Note, or Line Tag.
Difficult Moves are identified automatically from your unguided training results. They contain only your own repertoire moves and change as more training data becomes available: repeatedly missed moves appear, while moves you subsequently master can disappear again. Early entries may be provisional until enough attempts have been recorded.
In short: Critical Positions reflect what you consider important; Difficult Moves reflect what your training history shows you currently struggle with.
Choose a public Lichess or Chess.com account, or a PGN database file, and select a date range. Opening Lab uses up to 1,000 matching games. For PGN files, select the opponent name found in the file; name variants can be separated with semicolons. Repeated Weak Moves examines the first 30 half-moves, considers the player's moves from move 4 onward, and finds moves repeated from the same exact position in at least two different games.
Repertoire Deviations compares the opponent's games with one of your repertoires. It follows only game paths covered by that repertoire and, on move 3 or later, reports the first uncovered opponent move when it was the only, most frequent, or most recent choice from that exact position. Each finding includes its evaluation, path, matching games, and games in which the opponent chose another move.
It reviews relevant repertoire positions for objectively weak or practically difficult own moves, missing own continuations, and frequent uncovered opponent moves that are supported as strong by both evaluation and practical results, score especially well in practice, or demand a single good reply. Critical-reply opportunities are shown separately from dangerous opponent moves.
Green-coloured own moves are explicit continuations of the current path. Green-coloured opponent moves are explicitly covered from the same exact position, including transpositions. Red-coloured moves indicate high-scoring opponent options.
On the main page, open Main Settings and adjust the game data source, time controls, and rating buckets so the game data matches the pool you care about. In Repertoire Analysis, use Report Breadth & Depth: lower settings are faster and stricter; higher settings inspect more positions.
Starter, Intermediate, Advanced, and Very Advanced control how much of the opponent's play a line must represent. Starter focuses on foundational coverage, while higher levels retain progressively less common branches deeper into the repertoire.
It controls how broadly and deeply analysis searches. Low is faster and narrower; higher settings inspect more positions and require more time.
Game Reviews compare played games with your repertoires so you can see where your games followed, missed, or left prepared lines.
Use Game Reviews to compare your online games against your repertoires. When the report finds deviations, use Train Errors to practise the relevant repertoire positions.
Manage your imported repertoires here.
Or create your own repertoire with guidance from Opening Lab
Repertoire Side
Coverage
Uses up to 1,000 public rated standard Blitz, Rapid, and Classical games per selected side. The editable snapshot reflects the player's recurring habits through move 12 rather than engine-approved choices. Builds are limited to 1,200 lines; the result warns when less common branches were omitted.
Mark this position as critical and optionally give it a short name.
Add an optional label for this complete line and a note for the current position.
Review the line, navigate through it, and edit the ending safely.
Move Explorer
| Move | Eval | Share | White | Draw | Black |
|---|
-
Current Path
Repertoire Moves from This Position
Editor Status
Connect your accounts and run the report to list deviations from your repertoire.
No report generated yet.
Find objective opening errors in moves the opponent repeated across games, focusing on their only, most frequent, or most recent choices in a position.
Select a PGN database file. Separate name variants with semicolons.
No opponent preparation report yet.
The side you played is detected from your connected Lichess account or repertoire. Unclear games can be assigned below.
No manually selected games.
No critical positions are marked for this repertoire yet.
Run the analysis to generate findings for the active repertoire.
Selected repertoire: -
Please note that more breadth and depth will create more report findings. So specifically for smaller repertoires, it may make sense to start with low breadth & depth to catch the most important issues before diving deeper.
Load a position and click Master Games.
Checking connection...
Not enough training history yet.
Signed in as
Download your account record, activity timestamps, synchronized chess data, training progress, and saved reports. We recommend exporting before any planned deletion.
Want to leave? Permanently delete your account:
Practise openings against human moves for the selected rating range.
Start position
Loading repertoire list...