1. Acceptance of terms
By subscribing to, downloading, or running 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 Software. 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 self-hosted software that scans Kalshi, Polymarket, and sportsbook odds (via The Odds API) for same-market, cross-platform, and cross-bookmaker pricing spreads, and displays the resulting opportunities — the legs, prices, sizes, and links — for you to review. It runs on a computer or server you control, using credentials you supply. We do not operate it for you, and it never enters a trade or bet on its own initiative.
3. Plans: Base and Pro
Base includes opportunity detection, real-time feeds where available, optional Discord alerts, read-only portfolio views, and a direct link to each leg of an opportunity. Base does not submit orders. Every trade or bet you make based on it, you place yourself, directly on the relevant platform.
Pro includes everything in Base, plus an order ticket for opportunities whose legs are all on Kalshi and/or Polymarket. The order ticket lets you instruct the Software to submit those orders to the exchanges, as described in Section 4.
On both plans, opportunities involving a sportsbook are information only. ArbTrader does not place, and has no feature for placing, sportsbook bets. Sportsbooks generally do not offer a public betting API and many prohibit automated or assisted wagering; you place any sportsbook bet yourself, directly with the sportsbook.
Features within each plan may change over time as the Software is updated (see Section 16).
4. Pro order submission
If you subscribe to Pro and choose to enable order submission, the following applies:
- Every order is yours and requires your confirmation. The Software submits orders only after you open the order ticket for a specific opportunity, choose the quantity, affirmatively confirm, and press Submit. It has no setting that trades automatically, and nothing you configure grants it standing permission to trade.
- Orders come from your machine, under your account. Orders are sent directly from the machine running ArbTrader to Kalshi and/or Polymarket, authenticated with your own credentials. They are not routed through, placed by, or visible to us. For all purposes, you are the person placing the order.
- How legs are sent. Each leg is submitted as a separate limit order at or near the price shown on the ticket. Legs on different platforms, and often legs on the same platform, are not executed as a single atomic transaction. A leg may fill fully, partially, late, or not at all, and prices may change between the time a ticket is displayed and the time an order reaches the exchange.
- No automatic unwinding. If one leg fills and another does not, you may hold an unhedged position. The Software does not automatically cancel, close, complete, or hedge it; managing that position is your responsibility.
- Displayed figures are estimates. Costs, payouts, and spreads shown on a ticket exclude or only roughly estimate fees, and do not guarantee any outcome, fill, or profit.
- You can stay read-only. Order submission is off unless you add credentials with trading permission. You can use Pro, or Base, with read-only credentials only.
5. Eligibility
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. You're solely responsible for confirming that you're legally permitted to use Kalshi, Polymarket, and any sportsbook from your location; that your accounts on those platforms permit API access and, if you use Pro order submission, 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 Pro, transmits orders you have specified and confirmed. 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.
(Note for the site owner: offering software that submits orders for paying customers can raise regulatory questions — for example under U.S. commodities law — that depend on exactly how the product works and is marketed. Have a lawyer review this section and your Pro marketing before accepting live Pro payments.)
7. Subscription, trial, and billing
ArbTrader is offered as a monthly subscription on two plans: Base and Pro, each after a 3-day free trial. Launch pricing: subscriptions started on or before December 31, 2026 are $19.99/month for Base and $24.99/month for Pro. After that date, the listed price for new subscriptions is $30/month for Base and $45/month for Pro. 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 in your billing portal, you can switch between plans. Upgrades take effect immediately and downgrades 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.
You can cancel anytime; cancellation takes effect at the end of the current billing period and you keep access until then. Except where required by law, fees already charged are non-refundable, including partial months.
8. License and restrictions
While your subscription is active, we grant you a limited, non-exclusive, non-transferable license to download, install, and run 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, resell, sublicense, or redistribute the Software or its source, enable Pro features without a Pro subscription, use it to build a competing product or service, or remove or alter any proprietary notices. This license ends automatically if your subscription ends or these Terms are terminated.
9. Your accounts, API keys, and funds
ArbTrader is self-hosted: it runs on your own machine or server, using your own Kalshi API credentials and your own Polymarket wallet address or key. We never receive, store, or have access to your credentials, your funds, or your exchange accounts.
Your ArbTrader account. Your ArbTrader website account (email and password) is used only to manage your subscription, license key 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. Your license key works like a password — don’t share it.
If you enable Pro order submission, the credentials you provide can place orders and move funds. Anyone or anything with access to the machine running ArbTrader, or to those credentials, may be able to do the same. You are solely responsible for securing that environment and your credentials, and for every order submitted with them — we have no ability to see, reverse, reset, recover, or protect them 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 and cross-bookmaker matches can be wrong. Markets that look alike may resolve on different events, criteria, or deadlines, turning a hedge into an outright bet. Confirming a match is your responsibility.
- Pro order-submission code is built from each exchange'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 submitted 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 estimated, not live, fee figures, and can differ from your actual cost to trade or bet.
- Software, your machine, internet connections, exchange and sportsbook 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.
You use ArbTrader, and act on anything it shows you or submits 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, Polymarket, The Odds API, or any sportsbook. 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 Pro — 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 Pro 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, without regard to conflict-of-laws principles, and any dispute will be brought in the state or federal courts located in California. (Placeholder — set this to wherever you actually form your business, and confirm with a lawyer whether you want a mandatory arbitration and class-action-waiver clause here, which is common for SaaS terms but needs to be drafted correctly to be enforceable.)
18. Privacy
We collect the minimum needed to run your account and subscription — your email address, a salted hash of your password (never the password itself), whether you’ve confirmed your email, a login cookie, your IP address briefly for rate limiting, and payment details handled by Stripe on our behalf — and we send account emails (confirmation and password reset) through our email provider. We don't collect your exchange credentials, orders, or trading data, which never leave your own machine. (This section is a placeholder. If you collect anything else — support emails, analytics, marketing signups — you should publish a separate, complete Privacy Policy; required outright if you have any EU/UK or California users, under GDPR and CCPA respectively.)
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 self-hosted 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: [email protected] (update to whatever address you actually monitor).