Market ID (market_id)
A market ID is the “handle” an API uses to point to one exact market. Human-readable names can be messy because they can be long, ambiguous, or updated over time. An ID solves this by being stable and unambiguous.
In event-based datasets, a market can mean a specific question, contract, or outcome that will eventually resolve. When you request data, you usually don’t want to search by the full text every time. You want to store an ID once and reuse it for pulling prices, metadata, timelines, and resolution information.
You’ll often see the ID appear as a field like market_id. That field becomes the key you use to join tables or endpoints together. For example, a metadata endpoint might describe the market, while a time series endpoint returns the history of prices or probabilities for that same market. The market ID is what ties those pieces into one coherent record.
Good market IDs are designed to be stable. They typically don’t change when a description is clarified or when the market moves through lifecycle stages. If an ID does change, it creates real problems for downstream systems because stored references break. That’s why many APIs treat IDs as permanent.
From a developer standpoint, market IDs make data pipelines simpler. They allow caching, reduce repeated search calls, and make databases easier to index. They also make it safer to track many markets at once without mixing up similar names.
Why It Matters
Market IDs are what make large datasets joinable and automatable. Without them, it’s easy to mis-match markets, duplicate records, or lose track of a market when its title changes.
Why do APIs use market IDs instead of market names?
Names are designed for people, not for machines. They can include punctuation, be translated, or be edited for clarity, which makes them unreliable as keys. IDs are compact, consistent, and easier to store in databases. They also avoid ambiguity when two markets have similar wording.
How do you map a market_id to the correct market details?
Typically, you fetch metadata using the ID to retrieve the title, category, exchange, and lifecycle status. Many systems also store a local lookup table so they don’t need to re-fetch metadata for every request. If the API provides timestamps or versioning, you can detect when metadata changes and refresh your cache. Keeping that mapping updated prevents broken UI links and incorrect labeling.
Are market IDs stable over time?
In well-designed APIs, market IDs are intended to be stable so historical references remain valid. Stability is especially important for backtests and research because you need to match old observations to the same market today. If an API ever deprecates an ID, it should provide a clear replacement or redirect strategy. That way, downstream users can migrate without losing continuity.
Real-World Example
A researcher downloads daily probabilities for hundreds of prediction markets. They store each market_id in a database and use it to join price history with the market’s resolution criteria and final outcome.
Market ID (market_id) and Prediction Market API
FinFeedAPI’s Prediction Market API benefits from market IDs because prediction markets are best handled as discrete objects with histories and final outcomes. Using a market_id makes it easy to pull a market’s metadata, track its lifecycle, and query related time series without relying on long text titles. It also simplifies building watchlists and research datasets.