Stockfish cloud evaluation for a FEN position
Stockfish cloud evaluation for a FEN position. Returns depth, evaluation, and principal variation(s) when Lichess has the position cached.
5000 (raw units)
price
5
calls / 30d
5
unique payers
2026-09-08
updated
Provider
chess402.vercel.app · discovered, not yet claimed by its owner
Payment (x402 accepts[])
[
{
"scheme": "exact",
"network": "eip155:8453",
"payTo": "0xfbd46201267609ad3c66bd1b99b7f1cc80b1852f",
"asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"amount": "5000",
"maxTimeoutSeconds": 300
}
]Output schema
{
"bazaar": {
"info": {
"input": {
"body": {
"fen": "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1",
"multiPv": 1
},
"bodyType": "json",
"method": "POST",
"type": "http"
},
"output": {
"example": {
"depth": 22,
"fen": "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1",
"knodes": 13683,
"pvs": [
{
"cp": 27,
"moves": "e2e4 c7c5 g1f3 d7d6 d2d4 c5d4"
}
]
},
"type": "json"
}
},
"schema": {
"$schema": "https://json-schema.org/draft/2020-12/schema",
"properties": {
"input": {
"additionalProperties": false,
"properties": {
"body": {
"$schema": "https://json-schema.org/draft/2020-12/schema",
"additionalProperties": false,
"description": "Cloud-eval request: FEN position to analyze plus options.",
"properties": {
"fen": {
"description": "Standard FEN position string, e.g. 'rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1'",
"maxLength": 100,
"minLength": 15,
"type": "string"
},
"multiPv": {
"description": "Number of principal variations to return (1-5). Default 1.",
"maximum": 5,
"minimum": 1,
"type": "integer"
},
"variant": {
"description": "Chess variant. Default 'standard'.",
"enum": [
"standard",
"chess960",
"crazyhouse",
"antichess",
"atomic",
"horde",
"kingOfTheHill",
"racingKings",
"threeCheck"
],
"type": "string"
}
},
"required": [
"fen"
],
"type": "object"
},
"bodyType": {
"enum": [
"json",
"form-data",
"text"
],
"type": "string"
},
"method": {
"enum": [
"POST",
"PUT",
"PATCH"
],
"type": "string"
},
"type": {
"const": "http",
"type": "string"
}
},
"required": [
"type",
"method",
"bodyType",
"body"
],
"type": "object"
},
"output": {
"properties": {
"example": {
"$schema": "https://json-schema.org/draft/2020-12/schema",
"additionalProperties": {},
"description": "Cloud-eval response: depth, knodes, and principal variations.",
"properties": {
"depth": {
"description": "Search depth in plies.",
"maximum": 9007199254740991,
"minimum": -9007199254740991,
"type": "integer"
},
"fen": {
"description": "Echoed FEN that was evaluated.",
"type": "string"
},
"knodes": {
"description": "Kilonodes searched.",
"maximum": 9007199254740991,
"minimum": -9007199254740991,
"type": "integer"
},
"pvs": {
"description": "Principal variations (one per multiPv).",
"items": {
"additionalProperties": {},
"properties": {
"cp": {
"description": "Evaluation in centipawns from the side-to-move POV.",
"maximum": 9007199254740991,
"minimum": -9007199254740991,
"type": "integer"
},
"mate": {
"description": "Mate-in-N from the side-to-move POV, when applicable.",
"maximum": 9007199254740991,
"minimum": -9007199254740991,
"type": "integer"
},
"moves": {
"description": "Space-separated UCI moves of the principal variation.",
"type": "string"
}
},
"required": [
"moves"
],
"type": "object"
},
"type": "array"
}
},
"required": [
"fen",
"pvs"
],
"type": "object"
},
"type": {
"type": "string"
}
},
"required": [
"type"
],
"type": "object"
}
},
"required": [
"input"
],
"type": "object"
}
}
}Use it
curl
curl "https://chess402.vercel.app/api/cloud-eval" # -> 402 Payment Required, accepts[] lists how to pay # retry with a PAYMENT-SIGNATURE (or PAYMENT header) once paid
JavaScript
const res = await fetch("https://chess402.vercel.app/api/cloud-eval");
if (res.status === 402) {
const { accepts } = await res.json();
// pay one of accepts[] via an x402 client, then retry with the payment header
}Python
import httpx
res = httpx.get("https://chess402.vercel.app/api/cloud-eval")
if res.status_code == 402:
accepts = res.json()["accepts"]
# pay one of accepts[] via an x402 client, then retry with the payment headerMachine-readable
Everything on this page is also available as clean JSON at /resources/13032.json, and this resource appears in /discovery/resources and /discovery/search.