Quick answer: Kalshi, Polymarket US, Novig, ProphetX and Underdog Predict all let U.S. adults trade sports contracts on their apps, but they are not the same. Fees, minimum ages, funding options and state rules all differ, and one app, Novig, is closed in Nevada, Arizona and Michigan. Underdog Predict is also closed in New York. The best fit is the one that is open where you live and charges the fees you can live with. These apps are not sportsbooks, and you can lose every dollar you put in.
Last checked: October 22, 2026. Every fee, age rule, state rule and offer below comes from the app’s own official page, linked in the sources at the bottom. Offers and fees change, so confirm them in the app before you fund an account. This is information, not legal advice. New to the idea? Start with our guide, Prediction Markets vs Sportsbooks.
The five apps side by side
| Kalshi | Polymarket US | Novig | ProphetX | Underdog Predict | |
|---|---|---|---|---|---|
| What it is | Kalshi Inc. runs a CFTC-regulated exchange | U.S. exchange for regulated event contracts (polymarket.us) | Peer-to-peer sports market, CFTC-regulated | Sports prediction exchange with its own rulebook | Run by UDM, LLC, a CFTC-registered broker; trades on Underdog Exchange, Kalshi and Crypto.com |
| Sports markets | Yes | Yes (NFL, NBA, MLB, college football and more) | Yes, sports only | Yes, including parlays | Yes, as “Prediction Picks” |
| Trading fees | Taker fee = 7% × price × (1 − price) per contract. Maker fee is lower on some markets | Taker fee tops out at $1.74 per 100 contracts at 50 cents | Free on pre-game straight trades. Live and futures: 0.06 × price × (1 − price). Parlays: 0.10 × price × (1 − price) | Not published on the pages we checked | Example shows $0.02 per contract. “Additional exchange fees may apply” |
| Minimum age | 18+ | Not published on the pages we checked | 21+ | Not published (only its EdgeBoost deposit option says 21+) | 18+ |
| Ways to fund | Debit card, bank transfer, crypto, wire. Card deposits can carry a fee of up to 2% | Debit card, ACH, Apple Pay, PayPal, Venmo, USDC, wire | Bank transfer and crypto are free. Cards and Apple Pay carry a 3% fee | Debit card, Apple Pay, Google Pay, retail cash, bank, crypto, wire. $10 minimum deposit | Bank (Trustly), PayPal, card, Google Pay, Apple Pay, Venmo |
| State availability | No state list on the pages we checked | Not published on the pages we checked | All states except Nevada, Arizona and Michigan | Not published on the pages we checked | Not available in Arizona, Michigan, Nevada, New York and U.S. territories |
| New-user offer | Promo or referral credit of up to $500, mostly $15 (see below) | $25 in trading credits for a $10 deposit within 7 days | $50 in trade credits for a $10 deposit | $75 in credits for trading $50 in 30 days | No fixed offer found on its official pages |
Sources are listed at the bottom. Checked October 22, 2026. “Not published” means we could not find it on the official pages we checked, not that the app has no rule.
Kalshi
Kalshi is a prediction market run by Kalshi Inc. as a CFTC-regulated exchange. It is the biggest name in the group, and its sports contracts also power the sports markets inside Underdog Predict. You must be 18 or older.
Fees follow a formula. The taker fee is 7% of the price times the chance of losing, rounded up, on each contract. That makes the fee biggest near 50 cents and smaller near 1 cent or 99 cents. Bank (ACH) deposits and withdrawals are free. Card deposits can carry a fee of up to 2%.
The offer, in plain English: Kalshi’s terms describe a referral or promo-code credit of “up to $500.” That is a range, not a flat amount. Per Kalshi’s terms, 70% of people get $15, 24% get $35, 5% get $75, 0.65% get $100 and 0.35% get $500. You must be a new U.S. user, pass ID checks and trade at least $25 within 7 days (referral) or 30 days (promo code). The credit must be used within 7 days and can only be withdrawn after you trade the same amount.
Polymarket US
Polymarket US is the U.S. exchange for regulated event contracts, at polymarket.us. The international Polymarket site sends U.S. visitors there. We could not find its minimum age or a state list on the official pages we checked, so look at the sign-up terms for both.
The fee schedule lists a taker fee that tops out at $1.74 per 100 contracts at 50 cents. Makers who post orders can earn rebates by volume tier. You can fund with a debit card, ACH, Apple Pay, PayPal, Venmo, USDC or wire, and withdrawals to cards, ACH, Apple Pay, PayPal and Venmo are free.
The offer: Deposit at least $10 within 7 days of signing up and get $25 in promotional trading credits. Only your first deposit counts. The credits can be used for trades and fees but can’t be withdrawn as cash.
Novig
Novig is a peer-to-peer sports prediction market, regulated by the CFTC, and it only offers sports. You must be 21 or older. It says it is available nationwide except Nevada, Arizona and Michigan, based on where you are physically located when you trade.
Novig is the only app here with free pre-game straight trades. Live and futures trades cost 0.06 × price × (1 − price) per contract, and parlays cost 0.10 × price × (1 − price), built into the quoted price. Bank transfers and crypto are free to fund. Credit cards, debit cards and Apple Pay carry a 3% fee.
The offer: New members who verify their ID, link a payment method and deposit $10 or more get $50 in trade credits. One per person, and not available in every location.
ProphetX
ProphetX calls itself America’s sports prediction exchange and publishes its own rulebook. We could not find its regulator, its fee schedule, its minimum age or a state list on the official pages we checked, so we are not guessing. Read its rulebook before you sign up.
You can deposit with a debit card, Apple Pay, Google Pay, retail cash, online banking, crypto or wire. The minimum deposit is $10. Withdrawals go to your own bank, debit card, paper check or wire.
The offer: Trade at least $50 within 30 days of account approval and get $75 in credits. They arrive in three $25 installments, within 24 hours, on day 7 and on day 14. The second and third need the previous one fully used, and the funds can be withdrawn only after your positions settle.
Underdog Predict
Underdog Predict is run by UDM, LLC, which is registered with the CFTC as a futures commission merchant. Its “Prediction Picks” trade on Underdog Exchange, Kalshi and Crypto.com. You must be 18 or older, be a U.S. resident and be in a state where it operates. It is not available in Arizona, Michigan, Nevada, New York or U.S. territories.
The only fee we found is a worked example of $0.02 per contract, with a note that other exchange fees may apply, so there is no full schedule to compare. You can fund with a bank through Trustly, PayPal, a card, Google Pay, Apple Pay or Venmo.
The offer: We did not find a fixed new-user offer on Underdog’s official help pages. Its promotions change often, so we are not listing one.
How to pick one
- Start with your state. If you live in Nevada, Arizona or Michigan, Novig is out. Arizona, Michigan, Nevada and New York rule out Underdog Predict. Check the other apps’ terms for your state before you deposit.
- Check your age. Novig is 21+. Kalshi and Underdog Predict are 18+. For Polymarket US and ProphetX we found no minimum age.
- Look at the fee, not the bonus. A bonus is a one-time credit, while fees apply to every trade. Novig’s free pre-game straight trades are the lowest-cost option listed.
- Read the credit rules. Credits can’t be cashed out, and several expire or pay out in installments.
- Pick the funding you want. Bank transfers are free at Kalshi and Novig. Card deposits carry fees at Kalshi and Novig.
Are these apps legal where you live?
It depends on your state, and the answer is changing. Federal regulators say these exchanges can operate nationwide, but several states and courts disagree for sports contracts. In September 2026 a federal appeals court ruled that Ohio and Tennessee can regulate Kalshi’s contracts. We track the latest rulings in Prediction Markets vs Sportsbooks, and for state examples, see our guides to Arizona and Ohio. We can’t tell you what is legal where you live. Check your state gaming regulator or ask a lawyer.
What are the risks?
- You can lose everything you pay for a contract.
- Fees and taxes reduce what you keep.
- Bonus credits usually can’t be withdrawn as cash and can expire.
- Rules can change if a court rules or a state acts. An app can close in your state.
- Prediction markets are not sportsbooks. They may not have the same player protections as a state-licensed sportsbook.
If gambling is causing problems, call 1-800-MY-RESET (1-800-522-4700). Never risk money you need for bills. Looking for a sportsbook instead? See our bonus terms index.
Quick answers
Are prediction market apps sportsbooks? No. A sportsbook takes your bet and sets the odds. A prediction market matches you with another trader and charges a fee.
Which app has the lowest fees? On what we found, Novig, which lists free pre-game straight trades. ProphetX does not publish its fees on the pages we checked.
Do I need to be 21? It depends on the app. Novig requires 21. Kalshi and Underdog Predict require 18. Check each app’s sign-up terms.
Can I use these apps in every state? No. Novig and Underdog Predict list states where they are closed, and the legal fight over sports contracts is still going on.
Are the bonuses free money? No. They are trading credits with rules. Most can’t be withdrawn as cash.
Sources
- Kalshi: fee schedule, regulation, sign-up
- Kalshi offer: Referral and Promo Code Program terms
- Polymarket US: fees, incentives, terms
- Novig: fees, eligibility, offer terms
- ProphetX: rules, new participant bonus, deposits
- Underdog Predict: overview, state eligibility, Prediction Picks overview
- All checked October 22, 2026.
Affiliate disclosure: this page has no affiliate links today. If that changes, we will label them and update this note. Payment never affects how we describe or order an app. You must meet each app’s own age rules, and some apps are 21+. Gambling involves risk. Last checked October 22, 2026.
