{"uid":"cap_6_XRgbmM-kOnVU9cXQMgQ","slug":"chess-move-validator-9c84c02c","name":"Chess Move Validator","description":"Check whether a chess move is legal in a given FEN position and get the board state after it: resulting FEN, capture info, and whether the move gives check. Illegal moves return a clear verdict instead of an error, so game bots can handle bad input gracefully.","url":"https://x402.forgemesh.io/chess-move-validator","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"fen":{"type":"string","description":"FEN position string, or 'start' for the initial position"},"move":{"type":"string","description":"Optional move to validate/apply, SAN (Nf3) or UCI (g1f3)"}}},"responseSchema":{"type":"json","example":{"turn":"white","state":{"in_check":false,"game_over":false},"valid_fen":true,"legal_moves":["a3","a4","Nf3"],"move_applied":{"san":"e4","legal":true,"fen_after":"rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b KQkq - 0 1"}}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.002","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.002/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.002","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.002","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_rDCtL7nrYCnXYv1HKy6s2","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.002","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Validates whether a chess move is legal in a given FEN position and returns the resulting board state, capture info, and check status","exampleAgentPrompt":"Is the move Nf3 legal from the starting position, and if so, what's the FEN after it's played? Use the FEN 'start' and move 'Nf3'.","exampleUseCases":null,"resultDescription":"Returns whether the move is legal, the resulting FEN string after the move is applied, capture information (if a piece was taken), and whether the move puts the opponent in check. Illegal moves return a clear verdict rather than an error, allowing game bots to handle bad input gracefully.","failureModes":["Invalid FEN string returns a parse error or unclear board state","Move provided in unrecognized notation returns illegal verdict","Missing FEN field causes request rejection","Network timeout for high-load scenarios"],"whenToPreferThis":"Use this endpoint when building chess bots or game UIs that need reliable, graceful handling of illegal move inputs — it returns a clear legal/illegal verdict rather than throwing errors, making it ideal for input validation in automated game pipelines. Prefer this over local chess libraries when you want a stateless, pay-per-call microservice without dependency management.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-15T01:06:10.079Z","isFirstParty":false}