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Please sign into Lichess and then into Opening Lab.
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Select a node in the repertoire move tree.
Load a PGN file to begin.
Building move list...
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Game Data
| Move | White | Draw | Black |
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| Move | Eval ~ | Share | White | Draw | Black |
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Expected Moves
Final evaluation
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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.
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 for your own files, Opening Lab Repertoire for the supplied repertoires, or enter a name, side, and coverage option and select Open Editor to build a new repertoire.
These include white repertoires based on either 1.e4 or 1.d4 as well as black repertoires against anything that seems practically relevant at the relevant level. 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-position report, rename and delete actions, and the Daily inclusion switch.
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, path tags, 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.
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 💡 button to switch suggestions on. At an opponent position, Opening Lab searches for the next uncovered move that meets the Opponent Move Suggestions setting. After it stages that opponent move, play your own reply; the search then continues automatically in the current path or, for Broad repertoire coverage, the next relevant path. Select the button again to pause. 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.
Undo and Redo work within the current draft. Save applies all staged changes together and queues the updated repertoire for synchronization. If you try to close the editor with unsaved repertoire or observation changes, Opening Lab asks whether to discard them or continue editing.
Repertoire views can show move-tree structure, included Daily status, explorer popularity by source and filters, critical-position reports, and analysis findings for weak or risky repertoire spots.
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 round of Daily Training by selecting "Next Daily Training" upon completion of your Daily Training. But use this with care as it will not only increase the workload for the day but also workloads in the following days when repetitions become due. Second, you can use Customized Training to add more training after Daily Training. Pick the repertoire and mode you want, or use Random Lines/Random Positions/Critical Positions 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. You can also use Show Lichess Top 3 or look at Master Games from that position. Wrong prompts enter the retry queue for the current training type and are repeated until solved or the session is left.
No. Daily Training and Customized Training keep separate retry queues. Leaving Daily Training for Customized Training does not turn unresolved Daily retries into Customized prompts, and Customized retries do not change the current Daily target counter. Returning to Daily Training resumes its own remaining work and retries.
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.
The colours are feedback aids. In regular training, correctness is based on whether the move matches the repertoire target, and yellow/orange/red estimate how serious a wrong move appears. In Opening Sparring, every legal user move is accepted and the colour indicates its result quality in the selected Lichess player profile.
Choose a repertoire, side to train, and training mode. Random Lines, Random Positions, Specific Line, and Critical Positions provide different ways to focus a prompt-based session and require a repertoire. Opening Sparring plays an opening game from move 1 using moves from the selected Lichess rating and time-control profile, and it can also be used without creating or loading a repertoire.
Connect your personal Lichess account, then select Opening Sparring. If a repertoire is loaded, choose whether to play the repertoire side or the opponent side. When you play the repertoire side, Opening Lab selects opponent moves from Lichess Explorer without limiting them to your repertoire. When you play the opponent side, Opening Lab uses an available own repertoire move and falls back to Explorer if necessary.
No repertoire is required for Opening Sparring. Without one, choose Play White or Play Black. Opening Lab selects every app move from the chosen Lichess rating and time-control profile according to Explorer frequency, while every legal user move is accepted and assessed against the same profile. This allows you to practise common opening play before creating or importing a repertoire.
The session ends when no more common opening moves remain or the opening limit is reached. It does not add spaced-repetition results, retries, guidance results, or proficiency changes. At the end, Opening Lab first requests Lichess Cloud Evaluation. If no cloud result exists, Stockfish 18 Lite evaluates the final position locally in the browser. Explorer results are used only as a last fallback and are marked with ~. Values use White's perspective: + means White is better and - means Black is better; the evaluation colour reflects the side you played.
Opening Lab distributes the unmodified Stockfish.js browser engine under GPLv3. License · Corresponding source
Training Entry Mode controls where Daily or prompt-based Customized Training starts within a line. Due Moves Only prompts only the selected Daily target moves and autoplays access moves. 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. Opening Sparring always starts at move 1 and does not use this setting.
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.
Correct moves (unguided) and Wrong moves (unguided) summarize prompts answered without First-Time Guidance. Solved with guidance counts guided introductions, and New moves counts moves introduced during the current Daily run. Daily-trained repertoire moves shows current Daily coverage, while Not yet daily-trained shows the remainder. Exit closes the completed session; Next Daily Training starts an additional Daily round and can add future repetitions.
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. Both routes use the same Specific Line settings, target planning, retries, and progression through later prompts.
In Customized Training, change Side To Be Trained from Own Moves to Opponent Moves. Each prompt is tied to a position and includes every opponent move covered by the repertoire, including alternatives reached through transpositions. Solve all covered alternatives shown for that position. Own repertoire continuations are handled internally before the next opponent prompt, and choosing a position in Move Tree does not change the selected training side.
It reviews all relevant repertoire positions and reports practical risks, missing replies to well-scoring or otherwise dangerous opponent moves.
Green-coloured moves indicate moves that are already covered by your repertoire from the current position. Red-coloured moves indicate high-scoring opponent options.
On the main page, open settings using the âš™ button 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, and Advanced change the minimum explorer share required for continuous opponent-move suggestions in the repertoire editor. Starter focuses on the most common replies, while higher levels include progressively less common moves.
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.
Opening Lab keeps a local working copy and, for a signed-in Opening Lab user, queues repertoire and training-progress changes for account synchronization. When account state is loaded on another device, training changes are merged where possible. If conflicting repertoire versions require a choice, Opening Lab asks which version to keep.
An inactive Opening Lab session can expire after 30 days. The app then asks the user to sign in again. Session lifetime and repertoire or training-progress storage are handled separately.
Manage your imported repertoires here.
or create new
Repertoire Side
Coverage
Create a name tag for this critical position.
Save line tags and position annotations independently.
Review the line, navigate through it, and edit the ending safely.
Game Data
Loading position data...
| Move | Eval ~ | Share | White | Draw | Black |
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Current Path
Existing Repertoire Moves from This Position
Edit Notes
To add an alternative move to the repertoire, select the position where the new branch should begin, then play the new move on the board.
Analysis Observations
Edit your notes for findings tied to this line and save with ✓.
Connect your accounts and run the report to list deviations from your repertoire.
No report generated yet.
Generate a report of your marked critical positions.
No critical positions found.
Run the analysis to generate findings for the active repertoire.
No report generated yet.
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.
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