Institutes

{
  "data": {
    "accuracy_final_polls": [
      {
        "best_mae": 0.42,
        "institute": "Institut Wahlkreisprognose",
        "mean_mae": 1.06,
        "n_endpolls": 19,
        "sd_mae": 0.38,
        "worst_mae": 2.13
      },
      {
        "best_mae": 0.43,
        "institute": "Forschungsgruppe Wahlen",
        "mean_mae": 1.2,
        "n_endpolls": 34,
        "sd_mae": 0.58,
        "worst_mae": 2.92
      }
    ],
    "elections_in_backtest": 34,
    "explanation": "accuracy_final_polls: mean absolute error of each institute's last poll before past elections. house_effects_points: average deviation per party versus the o...",
    "house_effects_points": {
      "Forschungsgruppe Wahlen": {
        "AfD": -0.65,
        "CDU": -2.15,
        "Grüne": -1.3,
        "Linke": 2.42,
        "SPD": 1.9
      },
      "INSA": {
        "AfD": 0.8,
        "CDU": -2.33,
        "Grüne": -4.43,
        "Linke": 3.53,
        "SPD": 3.1
      },
      "Infratest dimap": {}
    },
    "model_weights": {
      "Forschungsgruppe Wahlen": 1.07,
      "INSA": 0.7,
      "Infratest dimap": 1.24
    }
  },
  "docs": "https://api.polls.karbach.digital/v1/",
  "model": null,
  "notice": "Scenario analysis based on published opinion polls. Not a prediction and not a voting recommendation. Coalitions are arithmetic majorities only, not statemen...",
  "project": "Ein Projekt von Karbach.Digital (https://karbach.digital)",
  "source": {
    "polls": "dawum.de",
    "polls_license": "ODbL 1.0",
    "polls_license_url": "https://opendatacommons.org/licenses/odbl/1-0/",
    "processing": "polls.karbach.digital (Max Karbach)"
  },
  "uncertainty": null,
  "updated_at": "2026-10-18 04:30:24"
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://api.polls.karbach.digital/v1/institutes'

# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - 'https://api.polls.karbach.digital/v1/institutes' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode

// npm i @x402/fetch @x402/evm viem
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

// Pays at most $0.02 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.02" });
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const pay = wrapFetchWithPayment(fetch, client);

// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $0.02 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fapi.polls.karbach.digital%2Fv1%2Finstitutes
const res = await pay("https://api.polls.karbach.digital/v1/institutes");
console.log(res.status, await res.text());

# pip install "x402[requests,evm]"
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client

# Pays at most $0.02 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.02"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.get("https://api.polls.karbach.digital/v1/institutes")
    print(res.status_code, res.text)