Limited strength

Making Stockfish play at a chosen rating.

Setting options.elo between 1320 and 3190 makes the engine deliberately choose weaker moves in a way calibrated to that rating, which is how training bots and casual opponents are built. The search still runs to the requested depth and costs the same; only move choice changes.

Example

+0.2

curl JavaScript Python

curl -s https://stockfishapi.com/v1/eval \
  -H "Authorization: Bearer $STOCKFISH_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"fen":"rnbqkbnr/ppp2ppp/4p3/3pP3/3P4/8/PPP2PPP/RNBQKBNR b KQkq - 0 3","depth":14}'

const res = await fetch("https://stockfishapi.com/v1/eval", {
  method: "POST",
  headers: { Authorization: `Bearer ${process.env.STOCKFISH_API_KEY}`, "Content-Type": "application/json" },
  body: JSON.stringify({
    "fen": "rnbqkbnr/ppp2ppp/4p3/3pP3/3P4/8/PPP2PPP/RNBQKBNR b KQkq - 0 3",
    "depth": 14
  }),
});
const data = await res.json();

import os, requests

r = requests.post(
    "https://stockfishapi.com/v1/eval",
    headers={"Authorization": f"Bearer {os.environ['STOCKFISH_API_KEY']}"},
    json={
        "fen": "rnbqkbnr/ppp2ppp/4p3/3pP3/3P4/8/PPP2PPP/RNBQKBNR b KQkq - 0 3",
        "depth": 14
    },
)
data = r.json()