Polymarket API key: how to create one on Polymarket US

Polymarket US’s documentation, read on October 22, 2026, describes no read-only scope for these keys, and the creation steps name no permission to choose. Scopes do exist on the institutional API, which signs with RSA keys: its guide lists read:positions, read:orders, read:reports, write:orders and others, and its reporting pages say the position and balance ledger downloads require read:positions. None of that says how a key made at polymarket.us/developer would be given or limited to a scope.

Kalshi’s keys work differently, which is why the two venues’ key guides differ:

How a read-only Kalshi key is made is on how to create a read-only Kalshi API key.

API keys

Created at polymarket.us/developer after identity checks, signing with Ed25519 per the docs’ signing example; no read-only scope described

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Position and balance ledgers

Documented for the institutional API; both require its read:positions scope, at about 5 downloads a minute per firm

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Key types

Ed25519, recommended and selected by default, or RSA 2048 for RSA-PSS clients

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Unticking Full access

Also unticks Trade, Transfers and Accept block trades; Portfolio balance and Read block trades stay, included by Read all data

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A key signs requests as your account. Where a venue offers a read-only scope, the key itself caps what any holder can do. Polymarket US’s documentation describes no such scope, so for a key handed to any third party, the limit is the code of the app that holds it. What that app says it calls, and how it stores the key, is what there is to go on.

Realize’s Polymarket client reads five things: your balances, your activities, your positions, the public price history and the market feed over WebSocket. It implements no endpoint that places an order or moves money, so a key connected to Realize cannot trade through it. The key is encrypted at rest.

• Every trade and position resolution in the activity feed.
• Rebates, deposits, withdrawals and transfers, kept apart from trades.
• Your open positions and cash balance.
• The public price of each market held on December 31.

What each of those holds, field by field, is on Polymarket trade history; how a year is filed from them is in how to file Polymarket taxes.

Can a Polymarket US API key be read-only?

Polymarket US’s documentation describes no read-only scope for the keys created at polymarket.us/developer, as of October 22, 2026. Its institutional guide lists scopes for the institutional API (read:positions, read:orders, read:reports, write:orders and others); the retail key-creation page describes none.

Where do I create a Polymarket US API key?

At polymarket.us/developer, once the identity checks on your account are done. Polymarket US collects your Social Security Number at signup and runs identity checks before any deposit or trade.

Can Realize place trades with my Polymarket US key?

No. Realize’s Polymarket client implements no endpoint that places an order or moves money. It reads your balances, activities and positions, the public price history and the market feed.

How is a Polymarket US key different from a Kalshi key?

Both can sign with Ed25519, and Kalshi also offers RSA. Kalshi’s Create API key dialog, as we captured it on October 8, 2026, has a Full access box that, unticked, also removes Trade and Transfers. Polymarket US’s documentation describes no equivalent option for its keys.