Skip to main content

​
Quick Answer

Polymarket, Kalshi and Opinion all let users trade outcomes, but they are not interchangeable. Kalshi operates as a CFTC-designated contract market. Polymarket has an international prediction-market product and a separate US regulatory path. Opinion is an on-chain prediction exchange built around the broader OPINION stack and Opinion AI. The right choice depends on whether you can access the product, whether the exact market is listed, the order-book depth at your size, the current fee preview and the resolution rule.

​
Key Takeaways

  • Start with access and eligibility; a platform you cannot lawfully use is not an option.
  • Compare the exact market wording, not just the event name.
  • All three use order-book mechanics, so spread and depth matter.
  • Fee models differ and change; use live previews and official schedules.
  • Resolution processes differ, and market-specific rules take precedence over summaries.

​
At a Glance

Product terms, market catalogs and access can change. Treat this as a decision framework, not a static ranking.

​
1. Access and Eligibility

Check the official product available in your location before comparing features. “Polymarket” can refer to different product paths, including Polymarket US. Kalshi eligibility and account options also vary. Opinion excludes restricted jurisdictions and may change supported account or funding methods. Never use a lookalike domain to bypass restrictions. Start with the official Opinion links directory, and apply the same domain-verification habit to every platform.

​
2. Market Coverage

The most important question is whether the venue lists the exact event and outcome you want. Category labels such as sports, politics, economics or crypto are too broad to decide this. Check the live catalog for:
  • the exact question and closing time;
  • whether binary and multi-outcome versions exist;
  • how much liquidity is available;
  • whether related markets create useful context;
  • whether the contract is still open for trading.
Do not rely on an old review’s statement that one platform “leads” a category. Catalog and liquidity can move with the news cycle.

​
3. Fees and Execution Cost

Platform fees are only part of cost.
  • Opinion: takers pay a market- and price-sensitive fee in the current 0%–2% range; makers are not charged; a $0.50 minimum fee applies.
  • Polymarket: takers pay on fee-enabled markets using category-specific curves; makers are not charged.
  • Kalshi: transaction fees are defined by its current schedule, and some markets may also carry maker fees.
The fair comparison is:
See Polymarket vs Kalshi vs Opinion Fees for the current formulas.

​
4. Order Books and Liquidity

All three venues require the same basic order-book literacy. The displayed last price is not necessarily the price available for your order. Inspect:
  • best bid and best ask;
  • spread;
  • available shares at each level;
  • likely average fill for your order size;
  • whether a limit order can wait without harming your strategy.
A deeper book can outweigh a slightly lower fee. Read Order Books, Spreads and Liquidity for a practical guide.

​
5. Resolution

The market’s written rule is the contract. Compare the definition of the outcome, named sources, deadline, treatment of cancellations or corrections, and dispute process. Opinion says most markets currently use Opinion AI as the primary oracle, while each market can specify its method. Polymarket publishes its own resolution process and market-specific sources. Kalshi contracts define settlement through their product terms and source rules. Two markets with similar titles can carry different probabilities because they do not resolve under identical conditions.

​
6. Funding and Custody

Funding rails, settlement assets and custody models differ. Confirm the supported asset, network, deposit method, withdrawal method and any third-party provider fee in the live product. Network details deserve special care. Sending an asset on the wrong network can be irreversible. Use the exact deposit instructions shown by the official app rather than copying an address from social media.

​
Which Platform Fits Which Need?

There is no need to force one platform to be best at everything. Many users evaluate venues market by market.

​
Where Opinion Fits

Opinion.trade is the live prediction exchange within the wider OPINION ecosystem. Its current differentiators are the OPINION stack, Opinion AI as the primary oracle for most markets, and an order-book fee structure that currently leaves makers uncharged. These are reasons to evaluate it—not reasons to skip due diligence. Start with What Is OPINION?, then verify the specific market, fee preview and resolution rule in the live app.

​
What to Watch

  • New regional product paths and eligibility changes.
  • Market-specific fee updates.
  • Liquidity migration around major events.
  • Changes to resolution and dispute procedures.
  • New funding rails, networks or settlement assets.

​
FAQ

It depends on the exact market and user. Compare access, market wording, depth, fee preview and resolution. No platform is best for every category and order size.
Opinion and Kalshi have different product and regulatory structures. Choose based on eligibility, listed contracts, execution cost and resolution rules rather than a universal ranking.
Yes. The CFTC currently lists Kalshi as a designated contract market. Regulatory status does not remove market, trading or contract-resolution risk.
The CFTC currently lists QCX LLC doing business as Polymarket US as a designated contract market. Users should distinguish that route from other Polymarket products and verify current eligibility.
There is no fixed winner. Market category, maker/taker status, price, size, minimums, spread and depth all change the realized cost.
Ease depends on location, funding method and comfort with order books or on-chain assets. Use a small test order only after verifying the official domain, fees and resolution rule.Educational information only. Prediction-market trading involves risk, and access or eligibility varies by jurisdiction.

​
Sources & References

  1. OPINION Docs — Current Opinion product architecture and official trading documentation
  2. OPINION Docs — Fees — Current Opinion fee policy and minimums
  3. OPINION Docs — Resolution — Current Opinion resolution statement
  4. Polymarket Docs — Fees — Current category fees and maker/taker structure
  5. Polymarket Docs — Resolution — Current Polymarket resolution process
  6. Kalshi Help Center — Fees — Current Kalshi fee guidance
  7. CFTC — Designated Contract Markets — Current DCM status for Kalshi and Polymarket US
All sources verified 2026-08-13. Prediction-market terms change frequently — verify against each platform’s current documentation before treating these numbers as decision-quality data. Editorial content, not investment or gambling advice.