2s Prediction Market Probability Watcher

x402

2s Prediction Market Probability Watcher is a paid API for AI agents from 2s.io, paid per call via x402, $0.125/call, status unknown (last checked 2026-09-14).

Registers a webhook-based watcher that fires a signed callback when a Polymarket prediction market outcome crosses a specified probability threshold.

Price / call$0.125

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StatusUnknown

How this service works

The (most) everything API: 575+ pay-per-call endpoints for AI agents — ground-truth data, a full AI gateway, and agent infrastructure (storage, queues, watchers). USDC via x402, no signup, no API keys, and upto billing: pay actual usage, not the quote.

Output

A watcher registration is created; when the monitored Polymarket outcome's probability crosses the specified threshold, 2s POSTs a signed event to the callbackUrl containing the event details and the echoed payload object. The X-2s-Signature header lets you verify authenticity. No synchronous data is returned beyond confirmation of registration.

Example use cases

Example prompt

“Set up a watcher on the Polymarket market with conditionId '0x1234abc...' — fire a webhook to https://myserver.com/hooks/pm when the first outcome (Yes) goes above 0.75 probability, up to 3 times, and tag it 'election-alert'.”

Technical details

Endpoint

POSThttps://2s.io/api/watchers/prediction-market

When to prefer

Use this endpoint when you need event-driven, asynchronous alerts on Polymarket prediction market probability movements without polling. It is ideal for agents or workflows that need to react to market sentiment shifts (e.g., trigger downstream actions when a market crosses a conviction threshold). Prefer this over manual polling when you need reliable, signed delivery with configurable fire counts and expiry.

Side effects

Invalid or unknown conditionId — watcher fails to bind to a market
callbackUrl unreachable or rejecting POSTs — callbacks silently fail or retry
Threshold out of range (not 0–1) — validation error
expiresInSeconds exceeds 90-day maximum — rejected
maxFires exceeds 1000 — rejected
Market resolves before threshold is crossed — watcher expires without firing
Signature verification failure on receiving end — caller bug, not API bug

Input

Schema · Request body

Field	Type	Description
label	string	Optional free-text tag.
payload	object	Arbitrary JSON echoed back in every callback.
maxFires	integer	Stop after this many callbacks (default 1).
threshold	number	Probability 0–1 to cross, e.g. 0.8.
callbackUrl	string	Signed event POSTed here (verify X-2s-Signature). Any http(s) URL.
conditionId	string	Polymarket market conditionId (from predict.market / predict.markets).
outcomeIndex	integer	Which outcome to watch (0 = first, usually Yes). Default 0.
conditionType	string	Fire when the probability goes above or below the threshold.
expiresInSeconds	integer	Active window in seconds (default 30d, max 90d).

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