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Chess Masters Opening Explorer
x402
Chess Masters Opening Explorer is a paid API for AI agents from chess402.vercel.app, paid per call via x402, $0.003/call, status unknown (last checked 2026-09-15).
Returns top moves, win/draw/loss statistics, and recent top master games for a given chess position from the Lichess masters database
Price / call$0.003
Success—
StatusUnknown
How this service works
Masters opening explorer for a position. Returns top moves, win/draw/loss rates, and recent top master games from the Lichess masters database.
Output
A list of top moves played from the given position in master games, each with win/draw/loss counts and percentages, plus a selection of recent top master games featuring that position including player names, results, and game references.
Example use cases
Example prompt
“What are the top master-level moves for the position after 1.e4 e5 2.Nf3 Nc6 — show me the win/draw/loss rates and a few recent grandmaster games from the Lichess masters database.”
Technical details
Endpoint
POSThttps://chess402.vercel.app/api/mastersWhen to prefer
Use this endpoint when you need opening theory data specifically from master-level (grandmaster/IM) games rather than general player games. Prefer this over a general opening explorer when the user wants high-quality move statistics validated by top-level play, or wants to see how real grandmasters have handled a position. Choose the Stockfish sibling endpoint instead if the user wants engine evaluation rather than historical human game data.
Side effects
- Invalid FEN or move sequence returns an error with no data
- Position not found in masters database returns empty move list
- Malformed request body causes a 400 error
- Network timeout or Lichess API unavailability causes a 503 or 504 error
- Position with very few master games may return sparse or no statistics
Input
{
"input": {
"body": {
"fen": "rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq e3 0 1",
"moves": 10,
"topGames": 4
},
"type": "http",
"method": "POST",
"bodyType": "json"
}
}Schema · Request body
| Field | Type | Description |
|---|---|---|
| fen | string | Standard FEN position string, e.g. 'rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1' |
| play | string | Comma-separated UCI move sequence to apply to the FEN before lookup (e.g. 'e2e4,e7e5'). |
| moves | integer | Max number of top moves to return. Default 12. |
| since | integer | Include games from this year onward. |
| until | integer | Include games up to this year. |
| topGames | integer | Number of recent top games to include. Default 4. |
Output
{
"black": 316848,
"draws": 573290,
"moves": [
{
"san": "c5",
"uci": "c7c5",
"game": null,
"black": 154647,
"draws": 257675,
"white": 188770,
"opening": {
"eco": "B20",
"name": "Sicilian Defense"
},
"averageRating": 2401
},
{
"san": "e5",
"uci": "e7e5",
"game": null,
"black": 63241,
"draws": 159451,
"white": 91760,
"opening": {
"eco": "C20",
"name": "King's Pawn Game"
},
"averageRating": 2410
},
{
"san": "e6",
"uci": "e7e6",
"game": null,
"black": 36635,
"draws": 62726,
"white": 53695,
"opening": {
"eco": "C00",
"name": "French Defense"
},
"averageRating": 2389
},
{
"san": "c6",
"uci": "c7c6",
"game": null,
"black": 25923,
"draws": 45898,
"white": 34474,
"opening": {
"eco": "B10",
"name": "Caro-Kann Defense"
},
"averageRating": 2402
},
{
"san": "d6",
"uci": "d7d6",
"game": null,
"black": 11704,
"draws": 16296,
"white": 17050,
"opening": {
"eco": "B00",
"name": "Pirc Defense"
},
"averageRating": 2389
},
{
"san": "g6",
"uci": "g7g6",
"game": null,
"black": 10802,
"draws": 11489,
"white": 12747,
"opening": {
"eco": "B06",
"name": "Modern Defense"
},
"averageRating": 2396
},
{
"san": "d5",
"uci": "d7d5",
"game": null,
"black": 5943,
"draws": 9001,
"white": 9361,
"opening": {
"eco": "B01",
"name": "Scandinavian Defense"
},
"averageRating": 2372
},
{
"san": "Nf6",
"uci": "g8f6",
"game": null,
"black": 5492,
"draws": 7960,
"white": 7898,
"opening": {
"eco": "B02",
"name": "Alekhine Defense"
},
"averageRating": 2374
},
{
"san": "Nc6",
"uci": "b8c6",
"game": null,
"black": 1800,
"draws": 2097,
"white": 2422,
"opening": {
"eco": "B00",
"name": "Nimzowitsch Defense"
},
"averageRating": 2367
},
{
"san": "b6",
"uci": "b7b6",
"game": null,
"black": 494,
"draws": 564,
"white": 882,
"opening": {
"eco": "B00",
"name": "Owen Defense"
},
"averageRating": 2371
}
],
"white": 419328,
"opening": {
"eco": "B00",
"name": "King's Pawn Game"
},
"topGames": [
{
"id": "jYSkjcuG",
"uci": "e7e5",
"year": 2019,
"black": {
"name": "Caruana, F.",
"rating": 2818
},
"month": "2019-08",
"white": {
"name": "Carlsen, M.",
"rating": 2882
},
"winner": null
},
{
"id": "boLujJkB",
"uci": "c7c5",
"year": 2019,
"black": {
"name": "Carlsen, M.",
"rating": 2882
},
"month": "2019-08",
"white": {
"name": "Caruana, F.",
"rating": 2818
},
"winner": "white"
},
{
"id": "Sxov6E94",
"uci": "e7e5",
"year": 2019,
"black": {
"name": "Carlsen, M.",
"rating": 2882
},
"month": "2019-08",
"white": {
"name": "Caruana, F.",
"rating": 2818
},
"winner": "white"
},
{
"id": "bbp4jgEb",
"uci": "c7c5",
"year": 2020,
"black": {
"name": "Caruana, Fabiano",
"rating": 2835
},
"month": "2020-06",
"white": {
"name": "Carlsen, Magnus",
"rating": 2863
},
"winner": null
}
]
}Schema · Response
{
"type": "json",
"example": {
"black": 198217,
"draws": 311203,
"moves": [
{
"san": "Nf3",
"uci": "g1f3",
"game": null,
"black": 64210,
"draws": 98421,
"white": 152340,
"opening": {
"eco": "C42",
"name": "Russian Game"
},
"averageRating": 2434
}
],
"white": 482141,
"opening": {
"eco": "C20",
"name": "King's Pawn Game"
},
"topGames": [
{
"id": "Sxov6E94",
"uci": "g1f3",
"year": 2019,
"black": {
"name": "Carlsen, M.",
"rating": 2882
},
"month": "2019-08",
"white": {
"name": "Caruana, F.",
"rating": 2818
},
"winner": "white"
}
]
}
}Tags
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