Terms of Service

1. Acceptance of terms

Who we are. ArbTrader (arbtrader.co) is an independent sole proprietorship based in California (“ArbTrader”, “we”, “us”). Contact: [email protected].

By subscribing to or using ArbTrader ("the Software," "the Service," "we," "us"), you agree to these Terms of Service. If you don't agree, don't subscribe or use the Service. If you're using ArbTrader on behalf of an organization, you're agreeing on its behalf and confirming you have the authority to do so.

2. What ArbTrader is

ArbTrader is a subscription website that scans Kalshi, Polymarket, Polymarket US and, for sports games, Novig for one-winner bundles, nested brackets and cross-platform pricing spreads, and displays the resulting opportunities, the legs, prices, sizes, and links, for you to review. You use it in your web browser at arbtrader.co. There is nothing to download. It never enters a trade or bet on its own initiative.

Exchange credentials you choose to add are held in your own browser, not on our servers (Section 9). Where the Service passes a request to an exchange on your behalf, it forwards a request your browser has already signed with your own credentials, and the exchange's answer back to you.

3. Plans: Base and Quant

Base is free and needs no payment details. It shows each qualifying opportunity the scanner finds, with its return and how long it has left, and the scanner coverage report. It does not include the legs of an opportunity, their prices or sizes, or links to them, and it does not send orders.

Quant is the paid plan. On October 23, 2026 the former Pro plan was merged into Quant: anyone subscribed to Pro gets every Quant feature at the price they already pay, and Pro is no longer sold. Quant includes everything in Base plus every leg of an opportunity with its market, side, price and resting size, a direct link to each leg, your own profit & loss computed in your browser, the state guide, the AI Analyst and the Whale Tracker (below), and the alerts, cross-platform pairs and order tickets described further down. A higher plan, Terminal, has been announced as coming soon; it is not available, and nothing about it is offered or promised until it launches.

AI Analyst research (Quant). The AI Analyst can produce a research report on an event: a summary of public reporting found by an AI model with web search, and an estimated chance for each outcome that the model works out from that reporting without being shown any market’s price. It is general information generated automatically from public web pages. It can be wrong, incomplete or out of date, it is not a prediction that any outcome will happen, and it is not financial, investment, legal or betting advice or a recommendation to buy, sell or hold any contract. ArbTrader is not a broker, adviser or exchange: it never holds your money, never takes custody of your funds or positions, and never places a trade without your confirmation. Any decision to trade is yours alone.

Whale Tracker and copy trading (Quant). The Whale Tracker shows large trades other people have made on Polymarket and Kalshi, taken from those platforms’ public data, with each platform’s current price for the outcome traded. Traders are shown only as the platform shows them (a display name and a pseudonymous wallet address on Polymarket; nothing on Kalshi). It is information about what third parties did, not a recommendation, endorsement, signal or advice from us, and a trader’s past results say nothing about their next trade. Copy trading is optional: it lets you send one fill-or-kill limit buy for the same outcome on Kalshi or Polymarket US, sized and confirmed by you, after you have acknowledged its risks. A copy is a bet on one outcome, not an arbitrage, and you can lose everything you put into it. Nothing is ever copied automatically.

Alerts, pairs and order tickets (Quant). Quant also includes email and Discord alerts, pricing for Kalshi ↔ Polymarket pairs, matched automatically by wording, numbers and deadline or added by you (an automatic match can be wrong: you are responsible for checking that both markets resolve the same way before trading), and an order ticket for the Kalshi and Polymarket US legs of an opportunity. The order ticket lets you instruct the Service to send those orders to Kalshi or Polymarket US, as described in Section 4. Polymarket.com (the international exchange) does not accept orders placed from other websites, so its legs are always placed by you. You are responsible for making sure your use of an API key through the Service is permitted by each platform's own terms.

Features within each plan may change over time as the Software is updated (see Section 16).

4. Order submission

If you use order tickets or copy trading (Quant) and choose to add Kalshi or Polymarket US credentials with trading permission, the following applies:

• Every order is yours and requires your confirmation. A buy is sent only after you open the order ticket for a specific opportunity (or the copy dialog for a specific whale trade), choose the quantity or amount, have the current prices re-checked, and confirm. The only settings that buy or open positions without a confirmation for each order are Auto-place and Resting orders (Terminal), described below. A sell of a position you hold is sent only after you confirm it, or under an Auto-sell you have armed for that position (below).
• Auto-sell is a standing instruction you give, for one position. If you arm Auto-sell on a specific open position and confirm the notice that comes with it, you instruct the Service to send, from your browser and without asking you again, limit sell orders for every leg of that position once the live order books show you could sell it for at least the profit target you set more than it cost, after estimated fees. It only sells while your dashboard is open in your browser, where your credentials are. While your dashboard is closed, the Service keeps watching that position using public market data and, the first time the target is reached, emails you (and posts to your Discord webhook if you have added one) with a link to sell it yourself; it cannot sell while your dashboard is closed. It never buys; it fires once and then switches itself off; you can turn it off at any time before it fires. Prices and fees used to decide it are estimates, the book can move while it sells, and some legs may sell while others do not; you remain responsible for the result, exactly as for an order you confirmed by hand.
• Auto-place is a standing instruction you give (Terminal). If you switch on Auto-place and accept the notice that comes with it, you instruct the Service to send, from your browser and without asking you again, orders for every spread that meets the rules you set: minimum return after fees, maximum dollars per spread, daily cap, payout window and platforms. Each spread is priced and sent the way an order ticket sends it (prices re-checked, fill-or-kill limit orders, nothing sent that the current prices show would pay back less than it costs), and if one leg fills and another does not, the Service tries to sell the filled leg back, which can be at a loss. Auto-place runs only while your dashboard is open and signed in with your credentials, counts only its own orders toward your daily cap, pauses itself if an order's result is unclear, and stops when you switch it off. You are responsible for the rules you set and for every order sent under them. We may pause Auto-place for everyone at any time.
• Resting orders are a standing instruction you give (Terminal, beta). If you switch on Resting orders and accept the notice that comes with it, you instruct the Service to post, from your browser and without asking you again, one post-only limit buy at a time on one leg of a Kalshi bundle that does not yet pay, priced so the whole bundle would pay at least the minimum return you set, within the dollars per order and daily cap you set. Each resting order expires after about two minutes and is re-posted while your dashboard is open, and is cancelled when you leave the tab; if you close the tab, an open order can still fill until it expires, and you would then hold that leg on its own. When a resting order fills, the Service buys the bundle's other legs with fill-or-kill orders; if they cannot be bought at a price that still pays, it sells the filled leg back at the best available bid, which can be at a loss, and pauses Resting orders. You are responsible for the settings you choose and every order sent under them.
• Orders are signed in your browser, under your account. Each order is authenticated with your own Kalshi credentials, which stay in your browser. Because Kalshi's API does not accept requests from web pages, the signed request passes through our servers on its way to Kalshi and the response passes back; we forward it, we cannot alter what you signed, and we never hold your credentials. For all purposes, you are the person placing the order.
• How legs are sent. Each Kalshi or Polymarket US leg is sent separately, as a fill-or-kill limit order at the price you approved. The leg with the least size available goes first, on its own, and the rest follow together. If a leg does not fill after other legs have filled, the ticket may try that leg once more, at a higher limit no greater than the price at which the whole bundle would break even after estimated fees; you authorize that second order when you confirm the ticket. If the bundle still can't be completed and you ticked the sell-back option on the ticket, the legs that filled are sold back at the best available bids, which can lose money. The ticket stops as soon as the exchange's answer on any leg is unclear. Legs are never executed as a single atomic transaction, and prices may change between the time a ticket is displayed and the time an order reaches the exchange.
• No automatic unwinding on manual tickets. If one leg of an order ticket you confirmed fills and another does not, you hold an unhedged position. The Service tells you what filled, but does not automatically cancel, close, complete, or hedge it, except that an Auto-sell you have armed on that position will sell it when its target is reached, and Auto-place sells back a leg that filled alone as described above; managing that position is your responsibility.
• Displayed figures are estimates. Costs, payouts, and spreads on a ticket are computed from each platform's published fee rules and the size resting at the quoted price; they do not guarantee any outcome, fill, or profit.
• You can stay read-only. No order can be sent unless you add Kalshi credentials with trading permission. You can use Quant or Base with read-only credentials, or with no credentials at all.

5. Eligibility

ArbTrader is for adults only. You must be at least 18 years old (or older, where the law or a platform requires) and able to form a binding contract to use ArbTrader, and you confirm this when you create an account. If we learn an account belongs to someone under 18, we will close it and delete its data. You're solely responsible for confirming that you're legally permitted to use Kalshi, Polymarket, Polymarket US and Novig from your location; that your accounts on those platforms permit API access and, if you use order tickets, API-based order entry; and that your activity complies with the laws, regulations, and platform rules that apply to you. Using ArbTrader does not make you eligible for any platform you aren't otherwise eligible to use.

6. No advice, no discretionary authority

ArbTrader surfaces pricing information and, on Quant and Terminal, forwards orders you have specified and confirmed or, on Terminal, that match the Auto-place rules you set. Nothing it displays, and nothing we say about it, is financial, investment, trading, betting, legal, or tax advice, or a recommendation to enter any trade or bet. Opportunities are the output of automated calculations, not a judgment that any trade is suitable for you.

We do not act as your broker, exchange, futures commission merchant, or agent; we do not hold or control your funds or accounts; and we do not exercise discretion over what, when, or how much you trade. You are solely responsible for every trading and betting decision you make, whether or not you used ArbTrader to inform or transmit it.

7. Subscription, trial, and billing

Base is free of charge and has no subscription. ArbTrader is offered as a subscription on two paid plans. Quant (monthly or yearly): its first 7 days are billed at the daily rate, $1.48 a day ($10.36), charged at checkout (one start per card); that amount is credited against your first monthly or yearly payment. Terminal (monthly; everything in Quant plus the Terminal screen and middles): its first 7 days are billed at $4.90 a day ($34.30), charged at checkout and credited against your first monthly payment. Price: $45/month or $449/year for Quant; $149/month for Terminal, plus any sales tax shown at checkout. Moving a running Quant plan to Terminal changes the price of that same subscription, prorated by Stripe. Members who subscribed at an earlier price, including founding members and subscribers to the former Pro plan, keep the price they already pay. Cancelling a paid plan returns the account to Base rather than closing it. We’ll email you at least 30 days before any change to the price of an existing subscription, and you can cancel before it takes effect. Subscriptions are billed through Stripe. Unless you cancel before your trial ends, your subscription begins and you're billed automatically; unless you cancel a paid subscription, it renews automatically each month at the then-current price for your plan until you cancel.

Where available on your account page or in your billing portal, you can pause your plan for a month or switch between monthly and yearly billing. Changes may take effect immediately or at the end of the billing period; Stripe may apply a prorated charge or credit for the change. Any price change for an existing plan will be notified to active subscribers in advance.

Prices are in US dollars. Any sales tax that applies is shown at checkout before you pay. There are no setup fees or other ArbTrader charges; trading fees on Kalshi, Polymarket, Polymarket US and Novig are charged by those platforms, not by us.

Referrals and affiliates. Each account has a share link. Someone who creates their first ArbTrader account through it gets 50% off their first paid month, applied as a one-time code at checkout (new Stripe customers only). From October 23, 2026, the person who shared the link earns a commission instead of a free month, under the separate Affiliate Agreement, which they must sign to be paid. Referring yourself, using fake or duplicate accounts, or offering the link through paid ads for our brand name isn’t allowed, and we may withhold or reverse rewards obtained that way. Rewards earned before that date are honored.

Creator codes. Some creators we partner with share their own code. Someone who creates their first ArbTrader account with a creator code gets 20% off their first 3 paid months, applied as a one-time code at checkout (new Stripe customers only). We pay the creator a commission; they never see your email or any other personal data, and a creator code can’t be combined with a friend referral.

You can cancel anytime from Manage billing on your account page; cancellation takes effect at the end of the current billing period and you keep access until then. Refunds are covered by our Refund Policy.

8. Your right to use the Service

While your subscription is active, we grant you a limited, non-exclusive, non-transferable right to access and use ArbTrader, with the features of your plan, for your own personal trading activity in your own accounts. You may not use it to trade or bet on behalf of anyone else, share your account, resell or redistribute the Service or its output, access it other than through the interface we provide (including scraping or automating the Service), attempt to reach paid features without a paid subscription, use it to build a competing product or service, or remove or alter any proprietary notices. This right ends automatically if your subscription ends or these Terms are terminated.

9. Your accounts, API keys, and funds

Connecting an exchange account is optional. If you do, your Kalshi API key ID and private key are stored in your browser, and the private key is imported so that the page can ask your browser to sign a request with it but cannot read the key itself back out. For Polymarket, only your public wallet address is stored. We never receive, store, or have access to your private keys, your funds, or your exchange accounts, and clearing your browser's site data removes the key from the browser (it does not revoke it at the exchange; do that on the exchange).

Your ArbTrader account. Your ArbTrader account (email and password) is used to sign in and to manage your subscription and billing. It is separate from your exchange accounts and never holds exchange credentials. Keep your password private and use one you don’t use elsewhere; you’re responsible for activity under your account.

If you add Kalshi credentials with trading permission, those credentials can place orders and move funds. Anyone with access to the browser profile you added them on may be able to do the same. You are solely responsible for securing that computer and browser, for the permissions you give the key at the exchange, and for every order sent with it; we have no ability to see, reverse, reset, recover, or protect your credentials for you.

10. Assumption of risk

You understand and accept that:

• Trading prediction-market contracts and betting on sports carry real financial risk, up to and including total loss of the amounts you trade or wager.
• Spreads are often small, short-lived, and contested by other automated traders; an opportunity may be gone, thinner, or illiquid by the time you act, on either plan.
• Cross-platform matches can be wrong. Markets that look alike may resolve on different events, criteria, or deadlines, turning a hedge into an outright bet. We never match them for you; confirming a match is your responsibility.
• The order-ticket code is built from Kalshi's and Polymarket US's published API documentation and has not been exercised against live trading accounts at scale; bugs, timing issues, API changes, or unexpected platform behavior may cause orders to fail, fill differently than shown, or be sent in error.
• Legs of a multi-leg trade are not placed atomically; one leg can fill while another fails, leaving you with an unhedged position that ArbTrader does not automatically unwind.
• Displayed spreads use each platform's published fee rules at the moment we checked, and can differ from your actual cost to trade or bet.
• The Service, your browser, internet connections, exchange APIs, and market data can fail, lag, or go offline without notice, and any of those can affect an opportunity or an order in progress. If a connection drops mid-order, the Service may be unable to tell you whether that order reached the exchange; your exchange account is the record that counts.

You use ArbTrader, and act on anything it shows you or sends at your instruction, entirely at your own risk.

11. Third-party platforms

ArbTrader is an independent tool and is not affiliated with, endorsed by, or sponsored by Kalshi or Polymarket. Your use of those platforms is governed by their own terms, not these. We don't control, and aren't responsible for, their uptime, pricing, fees, rules, rule changes, or decisions about your account, including if they limit, restrict, void activity on, or close an account, or restrict or terminate API access to tools like ArbTrader. It's your responsibility to use ArbTrader only in ways each platform's terms allow.

12. Disclaimer of warranties

ArbTrader is provided "as is" and "as available," without warranties of any kind, express or implied, including merchantability, fitness for a particular purpose, non-infringement, accuracy of any data or calculation, or that the Software will be uninterrupted, error-free, or secure, or that any order will be transmitted or filled as intended. No advice or information you get from us creates a warranty not stated here.

13. Limitation of liability

To the maximum extent permitted by law, we are not liable for any indirect, incidental, special, consequential, or punitive damages, or for any trading or betting losses, unhedged positions, missed opportunities, lost profits, or lost data, arising from your use of ArbTrader, including orders submitted, not submitted, or filled differently than expected through ArbTrader, even if we were advised of the possibility. Our total liability for any claim relating to the Software is limited to the subscription fees you paid us in the 3 months before the claim arose.

14. Indemnification

You agree to indemnify and hold us harmless from any claim, loss, or expense (including reasonable legal fees) arising from your use of ArbTrader, your trading or betting activity, orders submitted with your credentials, or your violation of these Terms, of any law, or of any third-party platform's terms.

15. Termination

You may stop using ArbTrader and cancel your subscription at any time. We may suspend or terminate your access if you violate these Terms, don't pay applicable fees, or if we reasonably believe your use poses a legal or security risk to us or others. Ending your subscription does not cancel or close any open orders or positions on third-party platforms; those remain yours to manage. Sections that by their nature should survive termination, including Sections 4, 6, and 9 through 14; continue to apply after your access ends.

16. Changes

We may update these Terms, our plans, or the Software from time to time. We'll post the updated Terms with a new "last updated" date; continuing to use ArbTrader after changes take effect means you accept them. If a change is material, including a change to how order submission works, we'll make a reasonable effort to notify active subscribers.

17. Governing law

These Terms are governed by the laws of the State of California, United States, without regard to conflict-of-laws principles, and any dispute will be brought in the state or federal courts located in California, unless the law where you live gives you the right to bring it elsewhere. Nothing in these Terms limits rights you have under consumer-protection law that can’t be waived by contract.

18. Privacy and cookies

How we collect, use and protect personal data is explained in our Privacy Policy, and the one cookie we use is described in our Cookie Policy. You can download your data or delete your account at any time from your account page.

19. Miscellaneous and about this document

If any part of these Terms is found unenforceable, the rest remains in effect. These Terms are the entire agreement between you and us regarding ArbTrader, and supersede any prior agreements on the subject. You may not assign these Terms without our consent; we may assign them in connection with a merger, acquisition, or sale of assets.

These Terms are ArbTrader's general policy for using the Service and are not a substitute for independent legal, financial, or tax advice. They're a working document that covers the standard bases for a software subscription connected to real trading platforms and real money, and may be revised as the Service and applicable law evolve; see Section 16. If you need advice specific to your situation, consult a qualified professional in your jurisdiction.

20. Contact

Questions about these Terms, billing, privacy or your data: [email protected]. We aim to reply within a few business days.