Predictefy vs Adjacent: Prediction Market Data APIs Compared (2026)
The Short Answer
Predictefy is the stronger Adjacent alternative for developers who need prediction-market data connected to a cross-venue trading workflow. The Predictefy prediction market API covers 15+ venues with normalized contracts, matching, books and client-signed execution. Adjacent combines market data with indices, reference rates, news and research. Choose Predictefy when your application needs to inspect the underlying contracts and act through supported venue integrations.
Key Takeaways
- Predictefy connects cross-venue discovery, prices, book data and trading.
- Adjacent supplies underlying market data as well as derived indices and reference rates.
- Adjacent's public API and MCP tier use a 15-minute delay; paid plans provide real-time access.
- Read the methodology and licensing terms before using a benchmark in a product.
Product details, access and monthly prices checked on October 27, 2026.
How do Predictefy and Adjacent compare?
| Requirement | Predictefy | Adjacent |
|---|---|---|
| Main workflow | Cross-venue prediction-market applications, research and trading | Market data, benchmarks, reference rates, news and research |
| Venue coverage | 15+ prediction-market venues | Market-data guide names Kalshi, Polymarket, Polymarket US and Gemini |
| Comparison model | Matched market clusters with venue-level records | Market records, similar-market search and derived reference-rate series |
| Interfaces | REST, WebSocket and beta SDK/MCP packages | REST, exports and MCP |
| Evaluation access | Free with 25,000 monthly credits | Anonymous public API and MCP, delayed 15 minutes |
| Paid plans | Builder $48.88/month; Pro $149/month | Pro $50/month; Premium $250/month |
Why choose Predictefy for the underlying market workflow?
A benchmark can summarize a theme, but a trading application must also identify the contract, outcome and venue behind the number. Predictefy provides normalized market records across 15+ venues and matches related listings through stable clusters.
That lets a developer move from a broad question to a venue-specific book. Cross-venue matching is available on every plan. The application can retain the original contract identity, compare observed prices and inspect the resolution terms before a user makes a decision.
Predictefy adds WebSocket updates, trader intelligence, paper trading and client-signed execution for supported venues. On Pro, the arbitrage feed checks requested depth, venue fees and resolution equivalence when qualifying a candidate. Those components help connect a research screen to an operational application.
What does Adjacent offer beyond an odds feed?
Adjacent publishes market data alongside derived indices and reference rates. Its current market-data guide names Kalshi, Polymarket, Polymarket US and Gemini, with prefixed identifiers for markets and events. It documents price history, trades, top-of-book quotes and candles.
Its reference rates combine source markets into a series and report the spread between them. The documentation describes source weights and methods such as volume weighting, simple averaging and a median. Rolling-contract chains let a reference series continue as its constituent contracts change.
Adjacent also links news and filings to its research environment. That can be relevant to a researcher who wants to explain a change in a theme or follow an index methodology. It is a distinct use case from evaluating a particular order against a venue's book.
How should you read an index or reference rate?
Start with the methodology. A reference rate may aggregate prices from several markets, while an index can follow its own scale and weighting rules. Do not treat every displayed index value as a raw contract probability.
Inspect the constituents, weights, roll schedule and observation time. A change can come from source prices moving or from the composition of the series. If you need to explain the movement, retain the underlying source records rather than storing only the final number.
For a trading comparison, use Predictefy to inspect the actual venue contracts and current supported book depth. A combined reference price serves a different purpose from an executable ask. Include fees and settlement rules before evaluating a cross-venue price gap.
What do the access and licensing terms change?
Predictefy Free includes 25,000 credits a month for evaluation. Builder is $48.88 with 250,000 credits, while Pro is $149 with 2,000,000 and adds arbitrage, the price-gap feed and history replay. Commercial use is an Enterprise contract term. The pricing guide sets out the current access rules.
Adjacent's Free public API and MCP tier return data delayed by 15 minutes. Pro is $50 a month and Premium is $250, with organization-wide usage limits. Their pricing documentation states that these plans do not permit redistribution or use in a financial product. Arrange the appropriate agreement for that use.
Compare data rights as early as feature coverage. A personal research dashboard, a customer-facing analytics app and a redistributed data feed can require different contracts.
How should you evaluate an Adjacent alternative?
- Choose one theme and identify the individual contracts needed to represent it.
- Use Predictefy matching to compare those listings and retain each venue's rules and identifiers.
- If using an Adjacent benchmark, inspect its weights, scale, roll schedule and delay separately.
- Test the data flow with observed timestamps, then confirm the license for the intended product.
Start with a Predictefy evaluation key and the cross-venue guide. Build the comparison around the contract decisions your users need to make.
Frequently Asked Questions
Is Predictefy an Adjacent alternative?
Yes, for prediction-market data and application development. Predictefy is the stronger choice for a 15+ venue workflow with matching, books, streaming and client-signed execution.
Does Adjacent provide underlying market data?
Yes. Its market-data guide covers markets, events, prices, trades, quotes and candles for Kalshi, Polymarket, Polymarket US and Gemini, in addition to indices and reference rates.
Is Adjacent's public API real time?
The anonymous public API and MCP tier use a 15-minute delay. Its paid Pro and Premium plans provide real-time access under their published limits.
Is a reference rate an executable contract price?
No. A reference rate combines sources according to a methodology. Evaluate the actual venue's contract, asks, depth and fees before placing an order.
Which Predictefy plan should a commercial app use?
Commercial use is an Enterprise contract term. Free supports evaluation; Builder and Pro provide their published usage allowances, with arbitrage and replay starting on Pro.