Comparison
ArbTrader vs Predictefy
Both tools look for prediction market arbitrage: bundles that pay more than they cost after fees. They're built for different traders. Predictefy is a multi-venue terminal and data API. ArbTrader is a scanner for Kalshi, Polymarket, Polymarket US and Novig traders that also finds the trade, places it, and copies whales. Here's how they compare, from each product's own published pages, checked October 16, 2026.
The short version
Pick ArbTrader if you trade on Kalshi or Polymarket US, want the full arbitrage feed for under $20 a month, and want whale copy trading with a stop-loss, a take-profit, or an exit that follows the whale out.
Pick Predictefy if you want an API or SDK, historical market data, or arbitrage across a long list of crypto-native venues.
Side by side
| ArbTrader | Predictefy | |
|---|---|---|
| Price | Base free; Quant $45/month, about $1.48 a day. Billed monthly or yearly, cancel anytime | Free tier with API credits; Builder $48.88/month adds the full arbitrage feed; Pro $149/month; Enterprise from $2,500 (their pricing post) |
| Venues | Kalshi, Polymarket and Polymarket US; 40,000+ open events swept; Novig sports games matched against Kalshi (beta) | 15+ venues per their site, including Kalshi, Polymarket, Gemini, Smarkets, Novig, SX Bet, Limitless, Hyperliquid, Opinion and Myriad |
| US traders | Built around Kalshi and Polymarket US; State Guide covers all 50 states | Many venues are crypto-native exchanges; check which are available where you live |
| Fees and freshness | Every spread priced after each platform’s fee formula, re-priced about every 15 seconds, with the size for sale and how many seconds ago it was seen | Gaps checked against live order books, with fees, depth and liquidity shown |
| Alerts | Email and Discord alerts on your own return and profit thresholds (Quant) | Real-time arbitrage alerts |
| Placing trades | One-tap Kalshi and Polymarket US tickets, each leg a fill-or-kill limit order you confirm (Quant) | Order routing from its terminal, and an execution API |
| Whale tracking and copy trading | Big Polymarket and Kalshi trades, top wallets, optional copy trading with stop-loss, take-profit, or selling when the whale sells (Quant) | Not listed on its arbitrage page or pricing post |
| API, SDK and data | No public API | REST and WebSocket API, JavaScript and Python SDKs, an MCP server for AI agents, and historical price data |
| Your keys | Kalshi key stays in your browser as a non-extractable key; never uploaded | Non-custodial; Kalshi keys sign in the browser |
What the price difference means
Real arbitrage spreads usually net about 0.5% to 3% after fees. At 2%, earning back $48.88 a month takes about $2,450 of filled spreads every month; earning back $45 takes about $2,250. If you're starting small, a cheaper full feed leaves more of your money for trading. The scanner pricing guide walks through this math.
What neither tool can promise
No scanner makes arbitrage risk-free. Prices can move before every leg fills, and two markets that look the same can settle under different rules. Read each market’s rules before trading; ArbTrader’s risks page covers what can go wrong.
Common questions
Is ArbTrader a Predictefy alternative?
Yes. Both find arbitrage between prediction markets. ArbTrader focuses on Kalshi, Polymarket, Polymarket US and Novig (beta), with the full arbitrage feed for $45 a month, order tickets for Kalshi and Polymarket US, and a Polymarket whale tracker with copy trading and automatic exits. Predictefy covers more venues and sells an API.
How much does Predictefy cost compared to ArbTrader?
Predictefy's own pricing post lists a free tier with API credits, Builder at $48.88 a month for the full arbitrage feed, Pro at $149 and Enterprise from $2,500. ArbTrader has a free Base plan and one paid plan, Quant, at $45 a month, about $1.48 a day, billed monthly or yearly. Prices checked October 23, 2026.
Which is better for US traders?
ArbTrader is built around Kalshi and Polymarket US, both US-regulated exchanges, and its State Guide shows where you can trade in all 50 states. Predictefy lists more venues, including crypto-native exchanges, so check which ones are available where you live before relying on them.
When is Predictefy the better choice?
If you want an API, SDKs, historical market data, or arbitrage across many crypto-native venues, Predictefy offers those and ArbTrader doesn't.
ArbTrader checks 40,000+ Kalshi, Polymarket and Polymarket US events, plus Novig’s sports games, and re-prices every open spread about every 15 seconds. Base is free, no card needed.
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