Connecting your accounts

Where to get each key, and what it’s used for

Every key or address below is imported straight into your own browser. Nothing is ever typed into arbtrader.co or stored on our servers; see each card for exactly what leaves this browser and what doesn’t.

Kalshi

Your private key is imported into this browser’s key store so that page code can sign with it but can’t read it back out. Requests are signed here and passed through arbtrader.co, because Kalshi’s API doesn’t accept calls from web pages, the key itself never leaves this browser.

  1. Log in at kalshi.com, then click your profile icon (top right).
  2. Go to Account → Profile Settings, or open kalshi.com/account/profile directly.
  3. Find the API Keys section and click Create new API key.
  4. Kalshi shows the private key once and downloads it as a text file; save it now, it can’t be shown again.
  5. Copy the Key ID shown next to it.
  6. Back on the dashboard’s Connections tab, paste the Key ID, and either upload that file or paste its contents into the private key box.
  7. A read-only key is enough for P&L; order tickets need a key with trading permission.

Polymarket

Polymarket positions and trades are public, so your P&L needs only your wallet address, no key, nothing to sign. Polymarket.com blocks orders from other websites, so its legs are always placed by you there. For Polymarket US order tickets, connect a Polymarket US key separately.

  1. Log in at polymarket.com and click your avatar (top right) to open your profile.
  2. The address bar now shows a URL ending in a long string starting with 0x, that’s your wallet address.
  3. Copy it and paste it into the Connections tab. No password or key is needed; Polymarket wallet activity is public data.

Polymarket US

For one-tap tickets on Polymarket US spreads (Quant). Polymarket US keys are Ed25519: the secret is imported into this browser’s key store so page code can sign with it but can’t read it back out. Requests are signed here and passed through arbtrader.co, the secret itself never leaves this browser.

  1. Get the Polymarket US app and complete identity verification, the app confirms once you’re approved.
  2. On the web, go to polymarket.us/developer and sign in with the same method (Apple, Google, or email) you used in the app.
  3. Click to create a new API key. Polymarket US shows a Key ID and a Secret Key.
  4. Copy the secret now; it’s shown only once.
  5. Paste the Key ID and Secret Key into the Connections tab.
  6. Keep signing in with that same method afterward; switching it can break this key.

Back to the dashboard