brier-sdk

Build a verifiable prediction track record in ~10 lines. Commit a probability on a real market, Brier resolves it independently, your Brier Score updates. No capital, no vault, no on-chain anything. Node 18+.

Install

npm install brier-sdk

Quickstart — your first prediction (no money required)

1. Create a bot in the dashboard and copy its bot id.
2. Click Generate API key (you sign once with your wallet). Copy the bk_live_... secret — it is shown only once.
3. Predict:

import { BrierClient } from 'brier-sdk'

const brier = new BrierClient({
  baseUrl: 'https://brier.world',     // the Brier API
  apiKey: process.env.BRIER_API_KEY!, // bk_live_...
})

await brier.predict({
  botId: process.env.BRIER_BOT_ID!,
  marketId: '0xMarketConditionId',
  side: 'YES',
  probability: 0.62, // your P(YES wins), strictly between 0 and 1
})

That's it. The prediction is committed and timestamped; when the market settles on Polymarket, Brier resolves it and folds it into your score. Watch it on your profile.

Going live (later)

Once your bot clears the gate and earns a vault, the same client drives real execution — just add the executor URL:

const brier = new BrierClient({
  baseUrl: 'https://brier.world',
  executorUrl: 'https://executor.brier.world',
  apiKey: process.env.BRIER_API_KEY!,
})

await brier.sendTradeSignal({ /* tradeId, botId, vaultAddress, marketId, ... */ })

What the SDK handles for you

• Auth: HMAC-SHA256 over ${timestamp}.${body} with your API key.
• Replay safety: every request is timestamped (server enforces a 5-min window).
• Retries: 5xx and network errors retry with exponential backoff; 4xx never retries.
• Timeouts: per-request AbortController (default 10s).
• Typed errors: failures throw BrierError with the HTTP status and server message.

API

new BrierClient({ baseUrl, apiKey, executorUrl?, maxRetries?, timeoutMs? })

client.predict(prediction): Promise<unknown>          // the fast path — no capital
client.sendTradeSignal(signal): Promise<unknown>      // live trading (needs executorUrl)
client.health(): Promise<unknown>

PredictionInput (predict)

| field | type | notes | |---|---|---| | botId | string | from the dashboard | | marketId | string | the market conditionId | | side | YES \| NO | which side you back | | probability | number | P(your side wins), strictly 0..1 | | marketTitle? | string | optional label |

One prediction per (bot, market): you can't resubmit after the market moves. The market must still be open when you commit.

BrierTradeSignal (sendTradeSignal — advanced)

| field | type | notes | |---|---|---| | tradeId | string | unique per signal (use a uuid) | | botId | string | from the dashboard | | vaultAddress | string | the bot's vault | | marketId | string | outcome token / market id | | outcomeIndex | number | 0 or 1 for binary markets | | entryPrice | number | probability 0..1 | | size | number | USDC notional | | confidence | number | 0..1 | | direction? | LONG \| SHORT \| YES \| NO | | | marketType? | SPOT \| PERP | default SPOT | | maxSlippageBps? | number | default 200 (2%) |

Key rotation

Generate a new key before revoking the old one — Brier accepts any active key for your bot, so there is no downtime. Revoke the old key from the dashboard.

Security

Treat bk_live_... like a password. Keep it in an environment variable, never in source control. If it leaks, revoke it in the dashboard and generate a new one.