PolySniper - Polymarket Arbitrage

Scan Polymarket for negRisk arbitrage gaps in real time. CLOB-verified signals with APR, spread, and orderbook depth. Stop refreshing Polymarket tabs. Start catching the gaps that actually pay. You trade prediction markets. You know how negRisk events work — when the sum of all Yes prices dips below $1.00, there's a guaranteed profit at settlement. The problem is these gaps close in seconds. By the time you manually check the orderbook across 6 or 8 outcomes, the opportunity is gone. Or worse — you spot what looks like a gap, buy in, and realize the mid-price was misleading. The real ask was higher. After fees, there was no edge at all. That's the gap between seeing a price and knowing a price. PolySniper closes it. NegRisk arbitrage on Polymarket is structurally simple — buy every Yes outcome for less than $1.00 total, collect $1.00 at settlement. But execution is anything but simple. - Mid-prices lie. The prices shown on the Polymarket event page are mid-points between the best bid and best ask. They do not reflect what you actually pay when you hit the ask side of the orderbook. - Fees eat your edge. Polymarket charges fees on net winnings. A spread that looks profitable at 2% might be break-even or negative after fees are deducted. - Multi-outcome events are tedious to scan. A presidential primary market might have 12+ outcomes. Adding up all the Yes ask prices manually — accurately, with real orderbook data — takes longer than the gap lasts. - Volume matters. A 5% spread on a market with $3 of ask-side liquidity is not a real opportunity. You need to know the executable depth before committing capital. Most traders either miss these gaps entirely or learn about them after the fact. Some build custom scripts, but maintaining API integrations across gamma and CLOB endpoints is a project in itself. PolySniper automates the entire detection pipeline so you can focus on execution. WHAT THIS EXTENSION DOES PolySniper is a Chrome extension that continuously scans Polymarket for negRisk arbitrage opportunities. It runs two verification phases — a fast pre-filter using the gamma API, followed by real orderbook verification against the CLOB API — so every signal you see reflects prices you can actually trade at, with fees already deducted. Here is what you get: Two-Phase Signal Verification — Phase 1 scans up to 500 events using gamma mid-prices to identify candidates where the total cost might be below $1.00. Phase 2 fetches real orderbook data from the Polymarket CLOB API, walks the ask side of each outcome, and recalculates the spread using actual executable prices. Only signals that remain profitable after the 2% fee buffer are shown. Precise APR Calculation — Every signal displays the annualized return based on actual spread, days to expiry, and fee-adjusted cost. The formula is transparent: ROI = spread / totalCost, APR = (ROI / daysLeft) x 365 x 100. No hidden rounding. Real Orderbook Depth — For each outcome in a signal, you see the volume-weighted average price and executable USD depth from the CLOB orderbook. You know exactly how much capital the opportunity can absorb before the price moves. Verification Badges — Signals verified against real CLOB orderbook data show a green checkmark. If the CLOB was temporarily unreachable for any outcome, the signal is marked with a yellow indicator and labeled as mixed or gamma-only, so you know the confidence level. On-Page Floating Panel — When you browse polymarket.com, a draggable panel shows live signals directly on the page. Click any signal to jump to that market instantly. Desktop Push Notifications — Pro users receive Chrome desktop notifications when a new signal meets their minimum APR threshold. Click the notification to open the market page directly. Whale Detection Filter — Focus on opportunities with meaningful liquidity. The whale filter highlights signals with $1,000+ in executable depth, so you skip thin markets. 1. Install the extension from the Chrome Web Store. 2. Open the popup or visit polymarket.com — scanning starts automatically. 3. Signals appear ranked by APR, with spread, ROI, days left, and depth data. 4. Click any signal to open the Polymarket event page and execute your trade. 5. Adjust minimum APR, depth thresholds, and refresh interval in Settings. That is it. No account required for the free tier. No API keys to configure. The extension handles all data fetching in the background. A single-pass scanner using gamma API prices would be faster, but it would also produce false positives. Gamma mid-prices are derived from the midpoint of the bid-ask spread — they do not represent the actual cost of buying the Yes outcome. The two-phase approach solves this. Phase 1 is cheap and fast — it pre-filters hundreds of events in one API call and typically narrows the field to 0-5 candidates. Phase 2 only fires for those candidates, fetching real orderbooks from the CLOB API in a single batch request. This keeps network usage minimal while ensuring every signal is backed by real executable prices. If the CLOB API is temporarily unavailable, PolySniper falls back to gamma-based signals with a clear warning label — so you are never left with zero data. SIGNAL HISTORY AND SETTINGS Configurable Refresh Interval — Free users scan every 60 seconds. Pro users can set intervals as low as 5 seconds for near real-time detection. Sound Alerts — Enable audible alerts in Settings to get notified without watching the popup. Available for Pro users. Custom Thresholds — Set your minimum APR (default: 50%) and minimum depth (default: $10 USD) to filter out noise. Only signals meeting both thresholds appear in your feed. All settings are stored locally using Chrome's storage API. Nothing is sent to any external server beyond the Polymarket data APIs and the token verification endpoint. Catching a Flash Gap: A presidential primary market with 8 outcomes briefly has Yes prices summing to $0.96. After the 2% fee buffer, total cost is $0.98 — a 2% spread. On $500 of executable depth, that is $10 in guaranteed profit at settlement. PolySniper catches this in under 10 seconds and pushes a desktop notification. By the time you manually checked all 8 outcomes, market makers would have closed the gap. Avoiding a False Positive: You see mid-prices summing to $0.95 on a 4-outcome event. Looks like a 5% spread. But the CLOB orderbook shows the real best asks sum to $0.99. After fees, the actual spread is negative. PolySniper's Phase 2 verification catches this and does not show it as a signal — saving you from a losing trade. Filtering Thin Markets: A small event shows a 15% spread, but the ask-side depth is only $8 across all outcomes. Even if the spread is real, you cannot deploy meaningful capital. With minimum depth set to $50, PolySniper filters this out automatically. Overnight Scanning: You leave your browser open with PolySniper running. At 3 AM, a gap opens on a breaking news event. The extension catches it, sends a desktop notification, and the signal is waiting in your popup when you check your phone. Without automated scanning, this opportunity would have opened and closed while you slept. Multi-Event Comparison: Three different events show signals simultaneously. PolySniper ranks them by APR, so you can deploy capital to the highest-returning opportunity first. Each signal shows executable depth, so you know which ones can absorb your full position size. WHAT THIS EXTENSION DOES NOT DO - It does not access your Polymarket account, wallet, or trading history. - It does not place trades on your behalf or interact with any blockchain. - It does not collect personal browsing data or track your activity outside of polymarket.com. The only permissions it uses: - storage — Save your settings and Pro token locally in Chrome - alarms — Schedule periodic market scans in the background - notifications — Send desktop alerts when new signals are found (Pro) - Host access to gamma-api.polymarket.com — Fetch public market data - Host access to clob.polymarket.com — Fetch real orderbook prices - Host access to polysniper.dsonline.workers.dev — Verify Pro subscription tokens No data leaves your browser except API requests to these three endpoints. The free tier includes 5 visible signals per scan, precise APR values, and a 60-second refresh interval scanning 100 markets. For most users exploring Polymarket arbitrage for the first time, this is enough to understand how the signals work and evaluate whether the tool fits your trading strategy. Free tier limits are displayed in the Account tab of the extension popup. THE MATH BEHIND EVERY SIGNAL Total Cost = sum of real best ask prices for all Yes outcomes Fee Buffer = 0.02 (2% of winnings, applied as additive buffer) Spread = 1.00 - (Total Cost + Fee Buffer) ROI = Spread / (Total Cost + Fee Buffer) APR = (ROI / Days to Expiry) x 365 x 100 Executable Depth = minimum USD-equivalent ask-side liquidity across all outcomes No hidden logic. No rounding tricks. The same formulas are used for both free and Pro signals. WHO THIS IS FOR - Polymarket traders looking for a systematic edge on negRisk events - Quantitative traders who want real orderbook verification, not mid-price estimates - Casual prediction market users exploring arbitrage for the first time - Anyone tired of manually summing Yes prices across multi-outcome events Install the extension, open the popup, and signals start appearing on the next scan cycle. The free tier works immediately with no sign-up. No account needed. No API keys. No wallet connection. Just install, scan, and trade.